| 2005 |
2 |
1 |
A Dynamic Operating System for Sensor Nodes |
<DIV ALIGN=JUSTIFY>
<p>Sensor network nodes exhibit characteristics of both embedded
systems and general-purpose systems.
As an embedded system, a sensor node must use little energy and be
robust to environmental conditions.
As a generalpurpose system, a node should provide common services that
make it easy to write applications.
TinyOS, the current state of the art in sensor network operating systems, focuses on
traditional embedded system constraints; reusable components implement
common services, but a node runs a single statically-linked
system image, making it hard to run multiple applications or incrementally
update applications.
We present SOS, a new operating system for mote-class sensor nodes
that implements a more dynamic point on the design spectrum.
SOS consists of dynamicallyloaded modules and a common kernel, which
implements messaging, dynamic memory, and module loading and unloading,
among other services.
Modules are not processes: they are scheduled cooperatively and there is no
memory protection.
Nevertheless, the system protects against common module bugs using
techniques such as typed entry points, watchdog timers, and primitive resource
garbage collection.
Individual modules can be added and removed with minimal system
interruption.
We describe SOS's design and implementation, discuss tradeoffs, and compare
it with TinyOS and with the Mat'e virtual machine for TinyOS.
Our evaluation shows that despite the dynamic nature of SOS and its higher-level kernel
interface, it performs comparably to TinyOS in terms of energy usage and
performance, and better in terms of energy usage during software updates.</p></DIV> |
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http://nesl.ee.ucla.edu/projects/sos/publications/sos_mobisys_05.pdf |
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http://nesl.ee.ucla.edu/projects/sos/publications/sos_mobisys_05_talk.ppt |
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Third International Conference on Mobile Systems, Applications and Services (Mobisys) |
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14 |
2005-06-06 |
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Seattle, WA |
USENIX/ACM |
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| 2004 |
12 |
1 |
Mobile Element Scheduling for Efficient Data Collection in Wireless Sensor Networks with Dynamic Deadlines |
Wireless networks have historically considered support
for mobile elements as an extra overhead. However, recent
research has provided means by which network can take
advantage of mobile elements. Particularly, in the case of
wireless sensor networks, mobile elements are deliberately
built into the system to improve the lifetime of the network,
and act as mechanical carriers of data. The mobile element,
which is controlled, visits the nodes to collect their data before
their buffers are full. It may happen that the sensor
nodes are sampling at different rates, in which case some
nodes need to be visited more frequently than others. We
present this problem of scheduling the mobile element in the
network, so that there is no data loss due to buffer overflow.
We prove that the problem is NP-Complete and give an ILP
formulation. We give some practical algorithms, and compare
their performances. |
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http://www.ee.ucla.edu/~arun/rtss.pdf |
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http://www.ee.ucla.edu/~arun/rtss.ppt |
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IEEE Real Time Systems Symposium (RTSS) |
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296 |
305 |
10 |
2004-12-06 |
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Lisbon, Portugal |
IEEE Press |
true |
true |
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| 2004 |
6 |
1 |
Intelligent Fluid Infrastructure for Embedded Networks |
Computer networks have historically considered support for
mobile devices as an extra overhead to be borne by the system.
Recently however, researchers have proposed methods by which
the network can take advantage of mobile components. We
exploit mobility to develop a fluid infrastructure: mobile
components are deliberately built into the system infrastructure
for enabling specific functionality that is very hard to achieve
using other methods. Built-in intelligence helps our system adapt
to run time dynamics when pursuing pre-defined performance
objectives. Our approach yields significant advantages for energy
constrained systems, sparsely deployed networks, delay tolerant
networks, and in security sensitive situations. We first show why
our approach is advantageous in terms of network lifetime and
data fidelity. Second, we present adaptive algorithms that are
used to control mobility. Third, we design the communication
protocol supporting a fluid infrastructure and long sleep durations
on energy-constrained devices. Our algorithms are not based on
abstract radio range models or idealized unobstructed
environments but founded on real world behavior of wireless
devices. We implement a prototype system in which infrastructure
components move autonomously to carry out important
networking tasks. The prototype is used to validate and evaluate
our suggested mobility control methods. |
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http://www.ee.ucla.edu/~arun/mobisys.pdf |
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The Second International Conference on Mobile Systems, Applications and Services (MobiSys) |
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99 |
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2004-06-07 |
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Boston, MA, USA |
ACM Press |
true |
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| 2005 |
2 |
2 |
ROPE: Robust Position Estimation in Wireless Sensor Networks |
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Proceedings of the International Conference on Information Processing in Sensor Networks (IPSN) |
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2005-04-27 |
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Los Angeles (UCLA) |
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| 2003 |
9 |
1 |
Computation Hierarchy for In-network Processing |
<DIV ALIGN=JUSTIFY><P>In this paper, we explore the network level architecture of distributed sensor systems that perform in-network processing. We propose a system with heterogeneous nodes that organizes into a hierarchal structure dictated by the computational capabilities. The presence of high-performance nodes amongst a sea of resource constrained nodes exposes new tradeoffs in the efficient implementation of network-wide applications. The introduction of hierarchy enables partitioning of the application into sub-tasks that can be mapped onto the heterogeneous nodes in the network in multiple ways. We analyze the tradeoffs between the execution time of the application, accuracy of the output produced and the overall energy consumption of the network for the different mapping of the sub-tasks onto the heterogeneous nodes in the network. We evaluate the performance and energy consumption of a typical sensor network application of target tracking via beamforming and line of bearing calculations on the different nodes. Our experiments show that more than 95% of time on average, the hierarchical network outperforms a homogeneous network for approximately the same energy budget.</p></DIV> |
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http://nesl.ee.ucla.edu/fw/ram/ram-homepage/content/papers/wsna_print.pdf |
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http://nesl.ee.ucla.edu/fw/ram/ram-homepage/content/presentations/2003_09_Hierarchy_RK_WSNA.ppt |
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Proceedings of the 2nd ACM international conference on Wireless sensor networks and applications (WSNA 2003) |
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68 |
77 |
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2003-09-19 |
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San Diego, CA |
ACM Press |
true |
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| 2004 |
6 |
2 |
CENS Tech Report: Real Action Gaming Robots (Ragobots) |
An emerging area of research in embedded systems is the use of actuation and controlled
mobility. Autonomous devices capable of performing varying degrees of self-initiated
motion can be introduced into a sensor network to provide several performance
advantages such as enhanced coverage, resource redistribution, zooming-in capability for
phenomenon of particular interest, repairing communication connectivity, fault detection,
calibration and localization. This opens up several research challenges in developing
methods for determining the use of motion and providing navigational and other support
for autonomous controlled mobility. Real Action Gaming robots (ragobots) is a
laboratory scale test-bed for exploring these research issues in a fun setting for students.<BR><BR>
Ragobots also provides an exciting application for embedded systems and is an important
educational aid for introducing students at all levels to sensor networks and robotics. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_06_Ragbot_CENS_Tech_Report_AK.JF.pdf?rev=HEAD |
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2004-06-01 |
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Center for Embedded Networked Se |
Center for Embedded Networked Sensing (CENS) |
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| 2012 |
1 |
1 |
Biomimetic Electrostatics for Submerged Oceanic Sensing, Communication, and Coordination |
<p>Navigation, localization, and targeting while completely submerged in
the ocean are all extremely difficult due to the lack of a proficient
sensor. The highly conductive nature of salt-water results in severe
radio-wave attenuation precluding the use of RADAR. Naturally-
occurring noise sources, high energy costs, long-wavelengths, and
surface turbidity restrict the use of SONAR imaging to low-
resolutions, depths, and far fields. The ocean’s dark, turbulent, and
silty disposition impedes optical imaging.</p>
<p>Nature knows another better way. Apteronotus Albifrons is a
nocturnal oceanic fish that cannot rely upon optical
notions of vision to navigate, hunt, or avoid predators. Instead, it
relies upon an electroreceptive capability achieved through a dense
grid of electric field (Voltage) sensors arrayed along both sides of
the body and concentrated around the head. It emits an electric field
into the water and senses the self-induced forces down its sides.
Objects in the vicinity that differ in conductivity from the
background ocean environment disturb the field, redistribute the
current, and hence the spatial distribution of voltages measured by
the fish.</p>
<p>This dissertation chronicles the effort to produce an engineered
sensor which mirrors the biological phenomenon of electroreception and
demonstrate its ability to “visualize” targets with different
conductivities from the background ocean environment at very high
resolution by detecting perturbations in a quasi-static electric field
(electrostatics). This culminates in the first Biomimetic
Electrostatic Images (BEI) and demonstrates the potential of the technology to provide significant advances in underwater scientific enterprises, military applications, as well as in medicine.</p> |
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http://nesl.ee.ucla.edu/fw/documents/thesis/2012/2012-JF-PHD.pdf |
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318 |
2012-01-01 |
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Los Angeles, CA |
UMI Dissertation Publishing |
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| 2004 |
3 |
1 |
Augmenting Film and Video Footage with |
With the advent of tiny networked devices, Mark Weiser’s vision of a world embedded with invisible computers is coming to age. Due to their small size and relative ease of deployment, sensor networks have been utilized by zoologists, seismologists and military personnel. In this paper, we investigate
the novel application of sensor networks to the film industry. In particular, we are interested in augmenting film and video footage with sensor data. Unobtrusive sensors are deployed on a film set or in a television studio and on performers. During a filming of a scene, sensor data such as light intensity, color temperature and location are collected and synchronized with each film or video frame. Later, editors, graphics artists and programmers can view this data in synchronization with film and video playback. For example, such data can help define a new level of seamless integration between computer graphics and real world photography. A real-time version of our system would allow sensor data to trigger camera movement and cue special effects. In this paper, we discuss the design and implementation of the first part of our
embedded film set environment, the augmented recording system. Augmented recording is a foundational component for the UCLA Hypermedia Studio’s research into the use of sensor networks in film and video production. In addition, we have evaluated our system in a television studio. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2004/ARS_Percom2004_NormanSu.pdf |
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IEEE International Conference on Pervasive Computing and Communications (PerCom) |
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3 |
12 |
10 |
2004-03-14 |
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Orlando, FL |
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| 2004 |
4 |
1 |
High Integrity Sensor Networks |
The quality of information returned by a sensor network is crucial to its performance. This presentation presents our initial ideas on which issues affect the integrity of sensed data. The material is foundational only, our further work in this area addressing specific problems is available through other publications. |
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http://www.ee.ucla.edu/%7Ekansal/papers/kansal_hisn.pdf |
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NESL Research Group Meeting |
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12 |
2004-04-25 |
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Los Angeles, CA |
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| 2005 |
1 |
1 |
Distributed Energy Harvesting for Energy Neutral Sensor Networks |
The brief work-in-progress report summarizes our efforts on energy harvesting systems, including both the system level algorithms and the hardware platforms fabricated to support experimentation. |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_pervasive.pdf |
http://csdl.computer.org/comp/mags/pc/2005/01/b1toc.htm |
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IEEE Pervasive Computing |
4 |
1 |
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69 |
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2005-01-01 |
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#<DocumentCategory:0x007f418e69b5a0> |
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| 2004 |
4 |
2 |
Sensing Uncertainty Reduction Using Low Complexity Actuation |
The performance of a sensor network may be best judged by the
quality of application specifc information return. The actual sensing
performance of a deployed sensor network depends on several
factors which cannot be accounted at design time, such as environmental
obstacles to sensing. We propose the use of mobility to
overcome the effect of unpredictable environmental influence and
to adapt to run time dynamics. Now, mobility with its dependencies
such as precise localization and navigation is expensive in terms of
hardware resources and energy constraints, and may not be feasible
in compact, densely deployed and widespread sensor nodes.
We present a method based on low complexity and low energy actuation
primitives which are feasible for implementation in sensor
networks. We prove how these primitives improve the detection capabilities
with theoretical analysis, extensive simulations and real
world experiments. The significant coverage advantage recurrent in
our investigation justifies our own and other parallel ongoing work
in the implementation and refinement of self-actuated systems.
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http://www.ee.ucla.edu/%7Ekansal/papers/kansal_ipsn04.pdf |
http://doi.acm.org/10.1145/984622.984679 |
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ACM Third International Symposium on Information Processing in Sensor Networks (IPSN) |
1 |
1 |
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388 |
395 |
8 |
2004-04-25 |
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Berkeley, CA |
ACM Press |
true |
true |
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#<DocumentCategory:0x007f418eb8a430> |
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| 2004 |
10 |
1 |
Reputation-based Framework for High Integrity Sensor Networks |
The traditional approach of providing network security has been to borrow tools from cryptography and authentication. However, we argue that the conventional view of security based on cryptography alone is not sufficient for the unique characteristics and novel misbehaviors encountered in sensor networks. Fundamental to this is the observation that cryptography cannot prevent malicious or non-malicious insertion of data from internal adversaries or faulty nodes.
We believe that in general tools from different domains such as economics, statistics and data analysis will have to be combined with cryptography for the development of trustworthy sensor networks. Following this approach, we propose a reputation-based framework for sensor networks where nodes maintain reputation for other nodes and use it to evaluate their trustworthiness. The framework is modularized; we will analyze each building block in detail in this paper. We will show that this framework provides a scalable, diverse and a generalized approach for countering all types of misbehavior resulting from malicious and faulty nodes.
We are currently developing a system within this framework where we employ a Bayesian formulation, specifically a beta reputation system, for reputation representation, updates and integration. We will explain the reasoning behind our design choices, analyzing their pros & cons. We conclude the paper by verifying the efficacy of this system through some preliminary simulation results.
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http://www.ee.ucla.edu/~saurabh/publications/f21-ganeriwal.pdf |
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ACM workshop on Security in Ad-hoc & Sensor Networks (SASN) 2004 |
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2004-10-25 |
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Washington D.C. |
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#<DocumentCategory:0x007f418f205530> |
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| 2003 |
11 |
1 |
Timing-sync Protocol for Sensor Networks |
Wireless ad-hoc sensor networks have emerged as an interesting
and important research area in the last few years. The
applications envisioned for such networks require collaborative
execution of a distributed task amongst a large set of sensor
nodes. This is realized by exchanging messages that are timestamped
using the local clocks on the nodes. Therefore, time
synchronization becomes an indispensable piece of
infrastructure in such systems. For years, protocols such as NTP
have kept the clocks of networked systems in perfect synchrony.
However, this new class of networks has a large density of
nodes and very limited energy resource at every node; this leads
to scalability requirements while limiting the resources that can
be used to achieve them. A new approach to time
synchronization is needed for sensor networks.
In this paper, we present Timing-sync Protocol for Sensor
Networks (TPSN) that aims at providing network-wide time
synchronization in a sensor network. The algorithm works in
two steps. In the first step, a hierarchical structure is established
in the network and then a pair wise synchronization is
performed along the edges of this structure to establish a global
timescale throughout the network. Eventually all nodes in the
network synchronize their clocks to a reference node. We
implement our algorithm on Berkeley motes and show that it can
synchronize a pair of neighboring motes to an average accuracy
of less than 20ms. We argue that TPSN roughly gives a 2x better
performance as compared to Reference Broadcast
Synchronization (RBS) and verify this by implementing RBS on
motes. We also show the performance of TPSN over small
multihop networks of motes and use simulations to verify its
accuracy over large-scale networks. We show that the
synchronization accuracy does not degrade significantly with the
increase in number of nodes being deployed, making TPSN completely scalable.
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http://www.ee.ucla.edu/~saurabh/publications/Sensyspaper03.PDF |
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ACM Conference SenSys, 2003. |
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2003-11-07 |
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Los Angeles |
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| 2013 |
8 |
3 |
Energy Management Based on Charging Behavior Prediction |
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https://dl.dropboxusercontent.com/u/35098178/MikhaelPrashanth_Poster.pdf |
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WHI Summer Intern Final Poster Session |
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2013-08-01 |
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Los Angeles, CA |
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#<DocumentCategory:0x007f418e63ae08> |
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| 2011 |
5 |
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SensorSafe: Framework for Privacy-Preserving Management of Personal Sensory Information |
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http://nesl.ee.ucla.edu/fw/documents/reports/2011/haksoo-sensorsafe-wh.pdf |
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| 2004 |
11 |
1 |
Sensor Networks for Media Production |
Emerging sensor network technologies will enhance entertainment production, providing both increased expressive capabilities and significant cost savings. The authors explore fundamental challenges of deploying sensor networks for production, concentrating here on feature film sets and networked sensing in
support of on-set activity. Film sequences are captured in an order driven by economics and logistics, which often differs drastically from the order presented to an audience. Scenes captured in ‘production time’ must be visually consistent when reassembled during editing. This demo’s driver application is continuity management, which uses records of environmental conditions on the set to support repeatable action by the cast and crew and a
consistent environment among many ‘takes’ of many ‘shots’ of many ‘scenes’. Techniques developed will ultimately also enhance the creative flexibility of directors and cinematographers by decreasing setup time and providing additional information for post-production. Given a scene, the system will record lighting equipment used, locations of lights, camera, and actors, as well as light intensity measurements, by fusing data from several different
sources. All data is stored and synchronized with each video frame via an interface to a standard SMPTE time clock source on the set. The data will be available during the shoot through an 802.11b connected tablet PC. |
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http://nesl.ee.ucla.edu/fw/documents/demos/2004/Demo_Sensys2004_Marianantoni.pdf |
http://portal.acm.org/citation.cfm?id=1031495.1031568 |
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The 2nd international conference on Embedded networked sensor systems (SenSys 2004) |
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2004-11-03 |
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Baltimore |
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| 2003 |
9 |
2 |
A Unified Network and Node Level Simulation Framework for Wireless Sensor Networks |
Low power consumption is an essential requirement for wireless sensor networks. In many situations un-tethered wireless sensor nodes are expected to operate on non-renewable batteries for extended periods of time. To survive in such regimes, the embedded software running on the sensor nodes should strive to optimize power consumption at the node and network levels. In this paper, we present a novel simulation framework for quantifying power consumption in a unified way that also reflects the node level performance to network-wide power estimation. At the node level, our framework combines power simulator for the StrongARM processor with a radio and a sensing component. This is then integrated into SensorSim, an enhanced version of the ns-2 network simulator that also incorporates the sensing aspects required to simulate realistic sensor network scenarios. We illustrate the capabilities of our simulation
framework to explore different power management schemes and interactions across the node level network layer and sensor field events using a representative example scenario. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2003/NetworkSim_Report2003_HeeminPark.pdf |
http://www.cens.ucla.edu |
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CENS Tech Reports |
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2003-09-07 |
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| 2003 |
9 |
3 |
Energy-Efficient Task Assignment Framework for Wireless Sensor Networks |
Tasks for sensor networks often have constraints such as lifetime and latency. Performance of a sensor network like energy consumption and latency is largely affected by how the task is mapped to the nodes in network. This paper presents
an energy-efcient task assignment and migration framework for sensor networks. With proposed framework, optimal task transformation and assignment is sought so as to minimize given cost function. Cost function reects total energy consumption in a network, maximum energy consumption among nodes and
maximum latency. Simulated annealing method is used to solve the task transformation and assignment problem. For run-time support, we developed distributed task migration method. While executing tasks in a node, if the remaining energy is less than threshold level, such tasks are migrated into neighbor node which is healthier. With demonstrative examples, we evaluate
our task assignment framework and distributed task migration features through Sensorsim simulation which is an extension of ns-2 simulator. We demonstrate that our framework can handle node heterogeneity and various cost function requirements. The experimental results show that elaborate assignments can save
more energy than simple assignment of aggregation functions and help in improving performance. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2003/TaskAssign_Report2003_HeeminPark.pdf |
http://www.cens.ucla.edu |
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CENS Tech Reports |
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| 2005 |
3 |
1 |
Securing Positioning With Covert Base Stations |
Until recently, the problem of positioning in wireless networks
has been mainly studied in a non-adversarial setting. Recently,
several solutions to this problem have been proposed which mainly
rely radio on (RF) signal propagation times and require highly
sophisticated hardware. In this work, we propose a new
approach to secure positioning, based on covert base
stations. Our system enables secure positioning with a broad
spectrum of positioning techniques: ultrasonic or RF, based on
received signal strength or on signal time of flight. We show that
security of our system depends on the precision of the positioning
systems and on the size of positioning regions. We generalize this
notion and capture this dependence analytically. We further show
how our system can be applied to secure positioning in sensor
networks. |
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http://lcawww.epfl.ch/capkun/TechrepCovert.pdf |
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NESL -UCLA Technical report |
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| 2004 |
4 |
3 |
ICRA RoboGaming |
Why play?<br>
<li>Just for fun…</li>
<li>Helps adapt to new technology</li>
<li>Flexible design</li>
<li>People at play</li>
<li>Switch context with ease</li>
<li>Employ a separate mental cognition</li>
<li>Are willing to acquire new skills</li>
<li>Are open to fanciful interpretations</li> |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_04_Ragobot_ICRArobogaming_AK.ppt?rev=HEAD |
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Presentation before Networked Info-Mechanical Systems (NIMS) Committee of the Center for Embedded Networked Sensing (CENS) |
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2004-04-01 |
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Center for Embedded Networked Se |
Center for Embedded Networked Sensing (CENS) |
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| 2004 |
4 |
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Ragobot (Rev. A) Photo Overview |
Photographic callout of the various components and functions of the Rev. A Ragobot (RBTBDYA) |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_04_Ragobot_PhotoOverview_JKF.ppt?rev=HEAD |
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Networked Embedded Systems Lab (NESL) |
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2004-04-01 |
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#<DocumentCategory:0x007f418ebba8b0> |
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| 2004 |
6 |
3 |
Ragobot Hardware |
Implementing Controlled Mobility & RFID in Sensor Networks:<BR>
<li>Noise degrades sensor performance! (far worse than calibration error)</li>
<li>Noise interferes with communications (radio)!</li>
<li>Need high efficiency given energy constraints</li>
<li>Need AC quiet power rails for best sensor performance </li><br>
THESE GOALS CONFLICT! Must find a compromise |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_06_Ragobot_EE206Final%28RFID%29_DL.JKF.ppt?rev=HEAD |
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UCLA EE206 |
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29 |
2004-06-01 |
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UCLA |
EE206 Spring 2004 |
true |
true |
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#<DocumentCategory:0x007f418eab1658> |
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| 2003 |
11 |
4 |
On the Interaction of Network Characteristics and Collaborative Target Tracking in Sensor Networks |
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http://www.ee.ucla.edu/~tsiatsis/research/pub/sensys03-abstract.pdf |
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Proceedings of the First International Conference on Embedded Networked Sensor Systems (SenSys), |
1 |
1 |
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316 |
317 |
2 |
2003-11-16 |
2003-11-16 |
Los Angeles, California, USA |
ACM |
true |
true |
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#<DocumentCategory:0x007f418f61c3a8> |
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| 2004 |
6 |
4 |
Robust Object Recognition for Mobile Sensor Nets |
In this paper, we describe a method for providing object recognition to mobile sensor nodes using RFIDs. Because mobile sensor platforms tend to have very noisy electrical environments, the mobile platforms with RFIDs must be carefully designed so that the noise does not affect the ability for the reader to sense an
RFID tag. We created an application that uses the RFID reader on the Ragobot moving in a random walk that searches for tags and reads and writes to them. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_06_Ragobot_ObjectDetection_DL.JKF.pdf?rev=HEAD |
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UCLA EE206 |
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7 |
2004-06-01 |
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EE 206 Spring 2004 |
UCLA |
true |
true |
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#<DocumentCategory:0x007f418f107480> |
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| 2003 |
12 |
1 |
Robogaming (CENS Retreat) |
<li><p>nemore real is more fun!</p><p>new research and education drivers</p></li> |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/kansal_CENS_RETREAT.ppt?rev=HEAD&sortby=date |
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Center for Embedded Networked Sensing (CENS) 2004 Retreat |
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4 |
2003-12-02 |
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2003 Retreat |
Center for Embedded Networked Sensing (CENS) |
true |
true |
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#<DocumentCategory:0x007f418f5ca238> |
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| 2004 |
3 |
2 |
Ragobots Progress Report to NIMS |
concept art<br>
system components<br>
development progress<br>
Robot hardware<br>
Robot software<br>
Server software<br> |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/Ragobots_March17_2004_NIMSmeet.ppt?rev=HEAD&sortby=date |
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Center for Embedded Networked Sensing (CENS) Tech Report |
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49 |
2004-03-17 |
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Networked Info-Mechanical System |
Center for Embedded Networked Sensing (CENS) |
true |
true |
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#<DocumentCategory:0x007f418fbf5090> |
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| 2005 |
3 |
2 |
RagoWorld: The Next Generation in ReMote Gaming |
Behind the Bot: A RagoStory<br>
• Entertainment
• Provide new interactive gaming environment
• Visual interesting and new potential games
• Education
• Fun platform for students to learn about embedded robots
• Provide teaching aids for complex systems
• Research
• Provide reconfigurable mobile platform for embedded
research
• New directions in adaptive actuation and coordinated
operation
• Isolate test algorithms by shifting other functionality to
central server |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_10_Ragobot_EEARR2004.pdf?rev=HEAD&sortby=date |
http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_10_Ragobot_EEARR2004.ppt?rev=HEAD&sortby=date |
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UCLA Electrical Engineering Department Annual Research Review 2004 |
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6 |
2004-10-01 |
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UCLA Electrical Engineering Depa |
UCLA EE Department |
true |
true |
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#<DocumentCategory:0x007f418cfdbf18> |
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| 2006 |
10 |
1 |
Real Action Gaming Robots (CENS ARR) |
We present a new robotic architecture for research in mobile sensor networks and new interactive gaming environments. The RagoWorld consists of a fully capable, modular mobile platform and an interactive gaming environment, replete with a diverse array of navigational hazards, sensing obstacles, and detectable objects. Currently, Ragobot, the robotic platform, is capable of traversing complex terrains, avoiding moderately sized objects, and reading and writing RFID tags. The next generation of Ragobots will support multiple different sensor node architectures and have more sensing modalities, such as inertial navigation and acoustic tracking. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_10_Ragobots_CENSARR2004.pdf?rev=HEAD&sortby=date |
http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_10_Ragobots_CENSARR2004.PPT?rev=HEAD&sortby=date |
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Center for Embedded Networked Sensing (CENS) 2004 Annual Research Review |
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1 |
2004-10-01 |
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CENS 2004 Annual Research Review |
Center for Embedded Networked Sensing (CENS) |
true |
true |
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#<DocumentCategory:0x007f418d16aeb0> |
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| 2004 |
10 |
2 |
The Uneven Equation |
A toy robot named "Ragobot" moves towards fourth-year materials engineering student Sophia Wong on the terrain she's helping to build. It's not surprising that fourth-year materials engineering student Sophia Wong says she feels like she knows every girl studying in the school of engineering with her -- there's not very many of them. "I know all... |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2004_10_Ragobot_DailyBruin.pdf?rev=HEAD&sortby=date |
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UCLA Daily Bruin |
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1 |
2004-10-04 |
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UCLA |
UCLA Daily Bruin |
true |
true |
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#<DocumentCategory:0x007f418e421d88> |
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| 2005 |
3 |
3 |
Ragobot (Rev. B) Photo Overview |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/ragobots/publications/2005_02_Ragobot_Rev_B.ppt?rev=HEAD&sortby=date |
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2 |
2005-02-01 |
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NESL |
Networked Embedded Systems Lab (NESL) |
true |
true |
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#<DocumentCategory:0x007f418fb98c50> |
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| 2003 |
5 |
1 |
Energy Harvesting for Sensor Networks |
This poster summarizes our initial efforts on developing a framework for harvesting energy and scheduling tasks in response to energy availability. |
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http://www.cens.ucla.edu/Education/Posters/NSF%20Poster%20Session-June%204/PosterFiles/8_EnergyHarvesting.pdf |
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CENS NSF Poster Session |
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0 |
2003-05-04 |
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Los Angeles, CA |
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true |
true |
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#<DocumentCategory:0x007f418f073b40> |
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| 2004 |
3 |
3 |
Energy Harvesting Support for Sensor Networking |
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http://deerhound.ats.ucla.edu:7777/pls/portal/docs/PAGE/NEWS_EVENTS/EVENTS/04_REVIEW_POSTERS/2ND_ANNUAL_REVIEW_POSTERS_FILES/ENERGY_HARVESTING.PDF |
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CENS NSF Poster Session |
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1 |
2004-03-04 |
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true |
true |
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#<DocumentCategory:0x007f418f87aed8> |
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| 2004 |
2 |
1 |
Fluid Infrastructure for Sensor Networks |
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http://www.ee.ucla.edu/~kansal/papers/cs213.pdf |
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CS213 Class Lecture |
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36 |
2004-02-04 |
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true |
true |
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#<DocumentCategory:0x007f418e669f50> |
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| 2005 |
3 |
4 |
Networked Infomechanical Systems: A Mobile Wireless Sensor Network Platform |
Networked Infomechanical Systems (NIMS) introduces a new actuation capability for embedded networked sensing. By exploiting a constrained actuation method based on rapidly deployable infrastructure, NIMS suspends a network of wireless mobile and fixed sensor nodes in three-dimensional space. This permits run-time adaptation with variable sensing location, perspective, and even sensor type. Discoveries in NIMS environmental investigations have raised requirements for 1) new embedded platforms integrating many diverse sensors with actuators, and 2) advances for in-network sensor data processing. This is addressed with a new and generally applicable processor-preprocessor architecture described in this paper. Also this paper describes the successful integration of R, a powerful statistical computing environment, into the embedded NIMS node platform. |
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IEEE/ACM Fourth International Conference on Information Processing in sensor Networks (IPSN-SPOTS) |
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376 |
381 |
6 |
2005-04-04 |
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Los Angeles, CA |
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true |
true |
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#<DocumentCategory:0x007f418f041140> |
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| 2005 |
3 |
5 |
Networked Infomechanical Systems: A Mobile Wireless Sensor Network Platform |
Networked Infomechanical Systems (NIMS) introduces a new actuation capability for embedded networked sensing. By exploiting a constrained actuation method based on rapidly deployable infrastructure, NIMS suspends a network of wireless mobile and fixed sensor nodes in three-dimensional space. This permits run-time adaptation with variable sensing location, perspective, and even sensor type. Discoveries in NIMS environmental investigations have raised requirements for 1) new embedded platforms integrating many diverse sensors with actuators, and 2) advances for in-network sensor data processing. This is addressed with a new and generally applicable processor-preprocessor architecture described in this paper. Also this paper describes the successful integration of R, a powerful statistical computing environment, into the embedded NIMS node platform. |
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IEEE/ACM Symposium on Information Processing in sensor Networks (IPSN-SPOTS) |
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6 |
2005-04-04 |
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Los Angeles, CA |
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true |
true |
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#<DocumentCategory:0x007f418e5a3f80> |
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| 2005 |
7 |
3 |
Secure Time Synchronization Service for Sensor Networks |
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To appear in the ACM Workshop on Wireless Security (WiSe) |
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0 |
2005-10-12 |
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true |
true |
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#<DocumentCategory:0x007f418ea2b058> |
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| 2004 |
3 |
4 |
Self-aware Actuaion for Fault repair in Sensor Networks |
Actuation ability introduces a fundamentally new design dimension in wireless ad-hoc sensor networks, allowing the network to adaptively reconfigure and repair itself in response to unpredictable run-time dynamics. One of the key network resources in these systems is energy and several uncontrollable factors lead to situations where a certain segment of the network becomes energy constrained before the remaining network. The performance gets limited due to the constrained sections. We argue that in this scenario, instead of rendering the complete network useless, the remaining energy resources should be reorganized to form a new functional topology in the network. We present methods for the network to be aware of its own integrity and use actuation to improve performance when needed. This capability of the system is referred to as “self aware actuation”.
In this paper, we consider a network where nodes (or a subset of the nodes) have traction ability. The network uses mobility to repair the coverage loss in the area being monitored by it. We present a completely distributed energy aware algorithm (referred to as Co-Fi) for coordinated coverage fidelity maintenance in sensor networks. The energy overheads of mobility are incorporated in the algorithm, thus leaving no hidden costs. Our preliminary analysis shows that Co-Fi can significantly help improve the usable lifetime of these networks.
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http://www.ee.ucla.edu/~saurabh/publications/1079.pdf |
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IEEE International Conference on Robotics and Automation |
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0 |
2004-03-08 |
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true |
true |
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#<DocumentCategory:0x007f418efe60b0> |
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| 2003 |
3 |
1 |
Aggregation in sensor networks: An energy-accuracy tradeoff |
Wireless ad hoc sensor networks (WASNs) are in need
of the study of useful applications that will help the researchers
view them as distributed physically coupled systems, a collective
that estimates the physical environment, and not just energylimited
ad hoc networks. We develop this perspective using a
large and interesting class of WASN applications called
aggregation applications. In particular, we consider the
challenging periodic aggregation problem where the WASN
provides the user with periodic estimates of the environment, as
opposed to simpler and previously studied snapshot aggregation
problems. In periodic aggregation our approach allows the
spatial-temporal correlation among values sensed at the various
nodes to be exploited towards energy-efficient estimation of the
aggregated value of interest. Our approach also creates a system
level energy vs. accuracy knob whereby the more the estimation
error that the user can tolerate, the less is the energy consumed.
We present a distributed estimation algorithm that can be
applied to explore the energy-accuracy subspace for a sub-class
of periodic aggregation problems, and present extensive
simulation results that validate our approach. The resulting
algorithm, apart from being more flexible in the energy-accuracy
subspace and more robust, can also bring considerable energy
savings for a typical accuracy requirement (five -fold decrease in
energy consumption for 5% estimation error) compared to
repeated snapshot aggregations.
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http://www.ee.ucla.edu/~saurabh/publications/SNPA03.pdf |
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IEEE Workshop on Sensor Network Protocols & Applications |
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0 |
2003-03-08 |
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true |
true |
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#<DocumentCategory:0x007f418fa512e8> |
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| 2005 |
3 |
6 |
Controllably Mobile Infrastructure for Low Energy Embedded Networks |
We discuss the use of mobility to enhance network performance for a certain class of applications in sensor networks. A major performance bottleneck in sensor networks is energy since it is impractical to replace the batteries in embedded sensor nodes post-deployment. A significant portion of the energy
expenditure is attributed to communications and in particular the nodes close to the sensor network gateways used for data collection typically suffer a large overhead as these nodes must relay data from the remaining network. Even with compression and in-network processing to reduce the amount of communicated data, all the processed data must still traverse these nodes to reach the gateway.
We discuss a network infrastructure based on the use of controllably mobile elements to reduce the communication energy consumption at the energy constrained nodes and thus increase useful network lifetime. In addition, our approach also yields advantages in delay tolerant networks and sparsely deployed networks. We first show how our approach helps reduce energy consumption at battery constrained nodes. Second we describe our system prototype which utilizes our proposed approach to improve the energy performance. As part of the prototyping effort we experienced several interesting design choices and trade-offs that affect system capabilities and performance. We describe many of these design challenges and discuss the algorithms developed for addressing these. In particular we focus on network protocols and motion control strategies. Our methods are tested using a practical system and do not assume idealistic radio range models or operation in unobstructed environments. |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_tmc06.pdf |
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IEEE Transactions on Mobile Computing (TMC) |
5 |
8 |
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16 |
2006-08-09 |
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IEEE |
true |
true |
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#<DocumentCategory:0x007f418ee4f760> |
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| 2005 |
1 |
2 |
Multiple Controlled Mobile Elements (Data Mules) for Data Collection in Sensor Networks |
Recent research has shown that using a mobile element to collect and carry data mechanically from a sensor network has many advantages over static multihop routing. We have an implementation as well employing a single mobile element. But the network scalability and traffic may make a single mobile element insufficient. In this paper we investigate the use of multiple mobile elements. In particular, we present load balancing algorithm which tries to balance the number of sensor nodes each mobile element services. We show by simulation the benefits of load balancing. |
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http://www.ee.ucla.edu/~dcjea/papers/dcoss05.pdf |
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http://www.ee.ucla.edu/~dcjea/papers/DCOSS_PRESENTATION.ppt |
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2005 IEEE/ACM International Conference on Distributed Computing in Sensor Systems (DCOSS '05) |
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0 |
2005-06-12 |
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Marina del Rey, California |
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true |
true |
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#<DocumentCategory:0x007f418e6c2510> |
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| 2005 |
2 |
3 |
Channels Characteristics for On-Body Mica2Dot Wireless Sensor Networks |
Networks also attract many researchers’ focuses, especially in the real-time health status monitoring field. However, the inconvenience of interconnecting sensors through wires not only induces high maintenance cost also limits freedom of human action. By attaching various types of bio-sensors to wireless sensor nodes, the unnatural wire constraints have been removed. The sampled data are transmitted through wireless interface and the system can response in time according to the different vital signs. Unlike wire connections, wireless connections are unstable and vulnerable to environments. It is our goal to study how human body affects wireless links qualities; we attached sensor nodes onto different parts of human body, and monitored the packet reception rate to learn how channels behave. We expect these experimental results can be used to assist constructing reliable and efficient wireless connections between on-body sensor nodes for related biomedical researches. |
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http://www.ee.ucla.edu/~dcjea/papers/mobiquitous05.pdf |
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0 |
2005-02-12 |
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true |
true |
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#<DocumentCategory:0x007f418d8e5528> |
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| 2005 |
6 |
5 |
RAGOBOT: A New Platform for Wireless Mobile Sensor Networks |
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Proceedings of the 1st IEEE International Conference on Distributed Computing in Sensor Systems (DCOSS 2005) |
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412 |
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1 |
2005-06-29 |
2005-07-29 |
Marina del Rey, CA |
Springer Verlag |
true |
true |
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#<DocumentCategory:0x007f418eb3c370> |
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| 2005 |
7 |
5 |
Multi-modal MAC Design for Energy-efficient Wireless Networks |
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Proceedings of the 2nd IEEE International Conference on Mobile Ad-Hoc and Sensor Systems (MASS 2005) |
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0 |
2005-11-29 |
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Washington, DC |
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false |
true |
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#<DocumentCategory:0x007f418e60f528> |
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| 2005 |
3 |
7 |
UCLA Engineers Collaborate on Unique Sensor System for Film Production |
A team of computer
science and electrical
engineering researchers in
the UCLA Henry Samueli
School of Engineering and
Applied Science are
partnering with faculty and
students in UCLA’s School
of Theater, Film and
Television (TFT) on a
sensor system for film
production as part of the
Advanced Technology for
Cinematography (ATC)
project. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/nesldoc/papers/ucla/2005_03_ATC_UCLA_Engineer_jf_hp_.PDF?rev=HEAD |
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UCLA Engineering News Center |
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3 |
2005-03-12 |
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Los Angeles, CA |
UCLA Media Relations |
true |
true |
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#<DocumentCategory:0x007f418f4625d0> |
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| 1991 |
4 |
1 |
An Integrated CAD System for Algorithm-Specific IC Design |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1991/J01_1991_tcad.pdf |
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IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems |
10 |
4 |
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447 |
463 |
17 |
1991-04-14 |
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true |
false |
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#<DocumentCategory:0x007f418f641478> |
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| 1992 |
9 |
1 |
Using VHDL for High-Level Mixed-Mode System Simulation |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1992/J02_1992_dtc.pdf |
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IEEE Design & Test of Computers |
9 |
3 |
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31 |
40 |
10 |
1992-09-14 |
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true |
false |
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#<DocumentCategory:0x007f418f0c41d0> |
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| 1995 |
3 |
1 |
System Level Hardware Module Generation |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1995/J03_1995_tvlsi_siera.pdf |
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IEEE Transactions on Very Large Scale Integration (VLSI) Systems |
3 |
1 |
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20 |
35 |
16 |
1995-03-14 |
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true |
false |
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#<DocumentCategory:0x007f418f146540> |
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| 1995 |
3 |
2 |
Optimum and Heuristic Techniques for Joint Optimization of Throughput and Latency |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1995/J04_1995_tvlsi_transform.pdf |
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IEEE Transactions on Very Large Scale Integration (VLSI) Systems |
3 |
1 |
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2 |
19 |
18 |
1995-03-14 |
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true |
false |
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#<DocumentCategory:0x007f418f294e10> |
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| 1995 |
6 |
1 |
SIERA: A Unified Framework for Rapid-Prototyping of System-Level Hardware and Software |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1995/J05_1995_tcad.pdf |
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IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems |
14 |
6 |
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676 |
693 |
18 |
1995-06-14 |
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true |
false |
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#<DocumentCategory:0x007f418e7fbdc8> |
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| 1996 |
3 |
1 |
Predictive System Shutdown and Other Architectural Techniques for Energy Efficient Programmable Computation |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1996/J06_1996_tvlsi.pdf |
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IEEE Transactions on Very Large Scale Integration (VLSI) Systems |
4 |
1 |
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42 |
55 |
14 |
1996-03-14 |
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true |
false |
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#<DocumentCategory:0x007f418ee0ebc0> |
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| 1996 |
3 |
2 |
Multiple Constant Multiplications: Efficient and Versatile Framework and Algorithms for Exploring Common Subexpression Elimination |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1996/J07_1996_tcad.pdf |
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IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems |
15 |
2 |
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151 |
165 |
15 |
1996-03-14 |
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false |
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| 1996 |
4 |
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SWAN: A Mobile Multimedia Wireless Network |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1996/J08_1996_pc_PA.pdf |
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IEEE Personal Communication |
3 |
2 |
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18 |
33 |
16 |
1996-04-14 |
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false |
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| 1996 |
8 |
1 |
Hardware-Software Architecture of the SWAN Wireless ATM Network |
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Journal of VLSI Signal Processing Systems |
13 |
2 |
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87 |
104 |
18 |
1996-08-14 |
1996-09-14 |
Hingham, MA, USA |
Kluwer Academic Publishers |
true |
false |
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| 1998 |
2 |
1 |
Ethersim: A Simulator for Application-Level Performance Modeling of Wireless and Mobile ATM Networks |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1998/J10_1998_ijcnis.pdf |
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International Journal of Computer Networks and ISDN Systems |
29 |
17 |
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2067 |
2090 |
24 |
1998-02-14 |
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false |
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#<DocumentCategory:0x007f418f172190> |
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| 1998 |
4 |
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Effect of Connection Rerouting on Application Performance in Mobile Networks |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1998/J11_1998_tcomp.pdf |
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IEEE Transactions on Computers |
47 |
4 |
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371 |
390 |
20 |
1998-04-14 |
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| 1998 |
10 |
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Behavioral Optimization using the Manipulation of Timing Constraints |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1998/J12_1998_tcad.pdf |
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IEEE Transaction on Computer-Aided Design of Integrated Circuits and Systems |
17 |
10 |
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936 |
947 |
12 |
1998-10-14 |
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| 1999 |
2 |
1 |
Advances in Wireless Terminals |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1999/J13_1999_perscommmag.pdf |
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IEEE Personal Communications |
6 |
1 |
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6 |
19 |
14 |
1999-02-14 |
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true |
true |
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| 1999 |
5 |
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Adaptive Radio for Multimedia Wireless Links |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1999/J14_1999_jsac.pdf |
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IEEE Journal of Special Area in Communications |
17 |
5 |
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793 |
813 |
21 |
1999-05-14 |
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| 1999 |
10 |
1 |
Adaptive Link Layer Strategies for Energy Efficient Wireless Networking |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1999/J15_1999_winet.pdf |
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Wireless Network |
5 |
5 |
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339 |
355 |
17 |
1999-10-14 |
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Hingham, MA, USA |
Kluwer Academic Publishers |
true |
true |
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| 1999 |
12 |
1 |
Power Optimization of Variable-voltage Core-based Systems |
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http://nesl.ee.ucla.edu/pw/NESL/papers/1999/J16_1999_tcad.pdf |
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IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems |
18 |
12 |
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1702 |
1714 |
13 |
1999-12-14 |
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true |
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#<DocumentCategory:0x007f418e27bc90> |
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| 2000 |
2 |
1 |
Design and Analysis of Low-power Access Protocols for Wireless and Mobile ATM Networks |
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http://nesl.ee.ucla.edu/pw/NESL/papers/2000/J17_2000_winet.pdf |
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Wireless Networks |
6 |
1 |
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73 |
87 |
15 |
2000-02-14 |
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Hingham, MA, USA |
Kluwer Academic Publishers |
true |
true |
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#<DocumentCategory:0x007f418f062598> |
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| 2003 |
2 |
1 |
Dynamic Adaptation of Networked Reconfigurable Systems |
<DIV ALIGN = JUSTIFY>
<p>
Networked Reconfigurable System comprises of a heterogeneous ad-hoc network of reconfigurable devices interconnected in a wired or wireless manner. This system exploits the reconfigurable computing resource available over the network to improve application performance and increase the robustness of the system to failures. The resource constraints of an individual device can be overcome by utilizing the idle resources in the network. There is a need for providing run-time software support to the system to enable the dynamic adaptation. Resource monitoring, scheduling and task allocation at a network level become very critical issues in ensuring the proper functioning of the system. This paper proposes a framework for dynamic adaptation of the Networked Reconfigurable Systems. A Network Resource Manager (NRM) is developed that orchestrates the reconfiguration process at every device in the network. A Local Reconfiguration Manager (LRM) at every device abstracts the underlying hardware and provides a common interface and set of services to the Network Resource Manager.</p></DIV> |
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http://nesl.ee.ucla.edu/fw/ram/ram-homepage/content/papers/SSRS.pdf |
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Workshop on Software Support for Reconfigurable Systems (SSRS) |
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6 |
2003-02-14 |
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Los Angeles |
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true |
true |
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#<DocumentCategory:0x007f418f2a4e50> |
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| 2004 |
8 |
2 |
Experience with a low power wireless mobile computing platform |
A detailed power analysis of a multi-radio mobile platform
highlights the complex tradeoffs between the computation,
storage, and communication subsystems. The particular mobile
device, which does not include an LCD or other on-board display,
can be used as a source for audio or video media files, or a
source/sink for secure data transfers. A version of the device has
been augmented with fine-grained power monitoring capability
and used to obtain detailed measurements of power dissipation in
the various subsystems. Analysis of these measurements sheds
light on the power consumption characteristics of different
applications, thereby providing hints to system designers about
potential areas for optimization. Specifically, this work contrasts
the power efficiency of the various wireless technologies
supported by the system. |
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http://www.ee.ucla.edu/~vijay/files/islped04_consus.pdf |
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ACM International Symposium on Low Power Electronics and Design |
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363 |
368 |
6 |
2004-08-14 |
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Newport Beach, CA |
ACM Press |
true |
true |
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#<DocumentCategory:0x007f418f32bae0> |
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| 2001 |
7 |
1 |
Dynamic fine-grained localization in Ad-Hoc networks of sensors |
The recent advances in radio and embedded system tech-
nologies have enabled the proliferation of wireless micro-
sensor networks. Such wirelessly connected sensors are re-
leased in many diverse environments to perform various mon-
itoring tasks. In many such tasks, location awareness is in-
herently one of the most essential system parameters. It
is not only needed to report the origins of events, but also
to assist group querying of sensors, routing, and to answer
questions on the network coverage. In this paper we present
a novel approach to the localization of sensors in an ad-
hoc network. We describe a system called AHLoS (Ad-Hoc
Localization System) that enables sensor nodes to discover
their locations using a set distributed iterative algorithms.
The operation of AHLoS is demonstrated with an accuracy
of a few centimeters using our prototype testbed while scal-
ability and performance are studied through simulation. |
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http://www.ee.ucla.edu/~simonhan/simon_paper/location_mobicom.pdf |
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Proceedings of the Seventh ACM Annual International Conference on Mobile Computing and Networking (MobiCom) |
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166 |
179 |
14 |
2001-07-14 |
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true |
true |
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#<DocumentCategory:0x007f418f0d2b68> |
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| 2004 |
11 |
2 |
A Unified Framework for Scheduling Problems with and without Power Control in Multi-hop Wireless Networks |
Scheduling problems in multi-hop wireless networks have been traditionally modeled as graph coloring problems, for which a transmission is assumed to be successfully received if the intended receiver is sufficiently apart from the sources of other simultaneous transmissions. In this paper, we underscore the disadvantages of such graph-based scheduling algorithms, which abstract away the physical layer details. Furthermore, we analyze and investigate several classes of scheduling problems in multi-hop wireless networks, which consist of fixed power link scheduling, power controlled link scheduling, fixed power node scheduling, and power controlled node scheduling. The goal is to find a minimum length time frame to schedule all the nodes or links in a TDMA setting. We present a unified set-covering based framework for these problems to model the interactions between simultaneous transmissions involved in the network, based on the received signal-to-interference and noise ratio (SINR). We then introduce a generic polynomial heuristic for performing the scheduling. Through our numerical results we show that our algorithm leads to a significant increase in the throughput level in comparison with conventional graph-based scheduling algorithms. We show that our generic algorithm can lead to an order of magnitude increase in the throughput of fully connected topologies with sufficient number of nodes over conventional graph-based scheduling algorithms. We also show that our scheme outperforms related schemes proposed in prior work. |
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http://www.ee.ucla.edu/~kulkarni/papers/unified.pdf |
http://www.ee.ucla.edu/~kulkarni/papers/unified.doc |
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35 |
2004-11-14 |
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true |
true |
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#<DocumentCategory:0x007f418f1a9b18> |
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| 2002 |
4 |
1 |
A Support Infrastructure for the Smart Kindergarten |
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http://nesl.ee.ucla.edu/pw/NESL/papers/2002/J20_2002_pervcomp.pdf |
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IEEE Pervasive Computing |
18 |
2 |
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49 |
57 |
9 |
2002-04-14 |
2002-06-14 |
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true |
true |
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#<DocumentCategory:0x007f418e4b86e8> |
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| 2003 |
5 |
2 |
Design and Implementation of a Framework for Efficient and Programmable Sensor Networks |
Wireless ad hoc sensor networks have
emerged as one of the key growth areas for wireless
networking and computing technologies. So far these
networks/systems have been designed with static and
custom architectures for specific tasks, thus providing
inflexible operation and interaction capabilities. Our
vision is to create sensor networks that are open to
multiple transient users with dynamic needs. Working
towards this vision, we propose a framework to define
and support lightweight and mobile control scripts that
allow the computation, communication, and sensing
resources at the sensor nodes to be efficiently harnessed
in an application-specific fashion. The
replication/migration of such scripts in several sensor
nodes allows the dynamic deployment of distributed
algorithms into the network. Our framework,
SensorWare, defines, creates, dynamically deploys, and
supports such scripts. Our implementation of
SensorWare occupies less than 180Kbytes of code
memory and thus easily fits into several sensor node
platforms. Extensive delay measurements on our iPAQbased
prototype sensor node platform reveal the small
overhead of SensorWare to the algorithms (less than
0.3msec in most high-level operations). In return the
programmer of the sensor network receives
compactness of code, abstraction services for all of the
node’s modules, and in-built multi -user support.
SensorWare with its features apart from making
dynamic programming possible it also makes it easy
and efficient without restricting the expressiveness of
the algorithms.
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http://www.ee.ucla.edu/~simonhan/simon_paper/SensorWare-Mobisys03.pdf |
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Proceedings of the First International Conference on Mobile Systems, Applications, and Services (MobiSys) |
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0 |
2003-05-14 |
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true |
true |
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#<DocumentCategory:0x007f418f9978e8> |
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| 2005 |
3 |
8 |
Computation Hierarchy for In-network Processing |
<DIV ALIGN = JUSTIFY>
<p>
In this paper we explore the network level architecture of distributed sensor systems that perform in-network processing. We propose a
system with heterogeneous nodes that organizes into a hierarchical structure dictated by the computational capabilities. The presence of
high-performance nodes amongst a sea of resource-constrained nodes exposes new tradeoffs for the efficient implementation of networkwide
applications. Our experiments show that even for a low relative density of resource-constrained nodes to high-performance nodes
there are certain gains in performance for a heterogeneous and hierarchical network over a homogeneous one. The introduction of
hierarchy enables partitioning of the application into sub-tasks that can be mapped onto the heterogeneous nodes in the network in multiple
ways. We analyze the tradeoffs between the execution time of the application, accuracy of the output produced and the overall energy
consumption of the network for the different mapping of the sub-tasks onto the heterogeneous nodes. We evaluate the performance and
energy consumption of a typical sensor network application of target tracking via beamforming and line of bearing (LOB) calculations on
the different nodes. Our experiments also include the study of the overall performance and energy consumption of the LOB calculation
using two different types of resource constrained sensor nodes (MICA and MICA2 nodes) and show how these metrics are affected by
changes in the node architecture and operation. Our results indicate that when using MICA motes as resource-constrained nodes, 85% of
the time on average the hierarchical network outperforms a homogeneous network for approximately the same energy budget. When using
MICA2 motes as resource-constrained nodes, 54% of the time the hierarchical network performs better than a homogeneous network with
approximately the same energy budget.
</p>
</DIV> |
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http://nesl.ee.ucla.edu/fw/ram/ram-homepage/content/papers/acm-monet-special-issue-final.pdf |
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ACM Mobile Networks and Applications |
10 |
4 |
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505 |
518 |
14 |
2005-01-14 |
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Springer Science+Business Media B.V |
true |
true |
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#<DocumentCategory:0x007f418ec66548> |
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| 2005 |
1 |
3 |
Exploiting radio hierarchies for power efficient wireless device discovery and connection setup |
We propose the coordinated use of multiple heterogeneous wireless
technologies to optimize the latency and power consumption of
mobile systems during device discovery and connection setup. We
present several multi-radio connection establishment techniques,
which exploit the wide disparity in the power and performance
characteristics of different radios to create an efficient and flexible
communication subsystem. Our techniques enable mobile devices to
combine the strengths of these diverse technologies, thereby
powering down higher power radios when their capabilities are not
needed and using a hierarchical radio structure for device discovery
and connection setup. Experiments using a prototype multi-radio
device show that the use of radio hierarchies results in significant
power savings, and often improves connection setup latency as well. |
|
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http://www.ee.ucla.edu/~vijay/files/vlsi05_hierarchy.pdf |
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IEEE International Conference on VLSI Design |
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774 |
779 |
6 |
2005-01-14 |
|
Calcutta, India |
IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418f9213c8> |
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| 2004 |
12 |
2 |
Joint MAC and Physical Layer Techniques for MIMO-based Wireless Networks |
This paper presents a rate adaptive medium access control (MAC) protocol for wireless networks with MIMO links. It is envisioned that the next generation high-throughput wireless LAN standard (IEEE 802.11n), which is currently under development, would use MIMO technology to achieve high data rates. An important design consideration is maintaining backward compatibility with the IEEE 802.11a/g standards. We adopt a joint MAC and physical layer strategy for channel access, based on the instantaneous channel conditions at the receiver. Our contributions include a transmit antenna and data rate selection scheme based on the optimal tradeoff between spatial multiplexing and diversity. The goal is to maximize the achievable data rate, given a MIMO channel instance and a target bit error rate. We also provide a feedback mechanism for the transmitter to obtain the rate selection settings from the receiver. Moreover, we maintain compatibility with legacy 802.11a/g devices and our protocol supports communication between devices with different number of antennas. The overall contribution is a MIMO physical layer aware, rate adaptive MAC protocol, which is compatible with 802.11a/g and can also be readily integrated with the 802.11n proposals. |
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http://www.ee.ucla.edu/~kulkarni/papers/mimac.pdf |
http://www.ee.ucla.edu/~kulkarni/papers/mimac.doc |
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12 |
2004-12-14 |
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UCLA Computer Science Department Technical Reports |
true |
true |
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#<DocumentCategory:0x007f418e414570> |
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| 2005 |
3 |
9 |
Sensor Network Software Update Management: A Survey |
Software management is a critical task in the system administration of enterprise scale networks.
Enterprise scale networks that have traditionally comprised of large clusters of workstations
are expanding to include low power ad-hoc wireless sensor networks (WSN). The existing
tools for software updates in workstations cannot be used with the severely resource constrained
sensor nodes. In this article, we survey the software update techniques in WSNs. We base our
discussion around a conceptual model for the software update tools in WSNs. Three components
of this model that we study are the execution environment at the sensor nodes, the software
distribution protocol in the network and optimization of transmitted updates. We present the
design space of each component and discuss in-depth the trade offs that need to be considered
in making a particular design choice. The discussion is interspersed with references to deployed
systems that highlight the design choices. |
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http://www.ee.ucla.edu/~simonhan/simon_paper/ijnm05.pdf |
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Internation Journal of Network Management |
15 |
1099 |
1190 |
283 |
294 |
26 |
2005-07-14 |
|
New York, NY, USA |
John Wiley & Sons, Inc. |
true |
true |
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#<DocumentCategory:0x007f418f9aefc0> |
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| 2003 |
1 |
1 |
Active Basestations and Nodes for Wireless Networks |
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Wireless Networks |
9 |
1 |
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37 |
49 |
13 |
2003-01-14 |
|
Hingham, MA, USA |
Kluwer Academic Publishers |
true |
true |
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#<DocumentCategory:0x007f418f0bdc90> |
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| 2005 |
3 |
10 |
Design considerations for solar energy harvesting wireless embedded systems |
Sustainable operation of battery powered wireless embedded
systems (such as sensor nodes) is a key challenge, and considerable
research effort has been devoted to energy optimization of such systems.
Environmental energy harvesting, in particular solar based, has emerged
as a viable technique to supplement battery supplies. However, designing
an efficient solar harvesting system to realize the potential benefits of
energy harvesting requires an in-depth understanding of several factors.
For example, solar energy supply is highly time varying and may not
always be sufficient to power the embedded system. Harvesting components,
such as solar panels, and energy storage elements, such as batteries
or ultracapacitors, have different voltage-current characteristics, which
must be matched to each other as well as the energy requirements
of the system to maximize harvesting efficiency. Further, battery nonidealities,
such as self-discharge and round trip efficiency, directly affect
energy usage and storage decisions. The ability of the system to modulate
its power consumption by selectively deactivating its sub-components
also impacts the overall power management architecture. This paper
describes key issues and tradeoffs which arise in the design of solar
energy harvesting, wireless embedded systems and presents the design,
implementation, and performance evaluation of Heliomote, our prototype
that addresses several of these issues. Experimental results demonstrate
that Heliomote, which behaves as a plug-in to the Berkeley/Crossbow
motes and autonomously manages energy harvesting and storage, enables
near-perpetual, harvesting aware operation of the sensor node. |
|
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http://www.ee.ucla.edu/~vijay/files/ipsn05_heliomote.pdf |
|
http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/nesldoc/presentations/2005_04_IPSN_Heliomote_vr.jh.jf.PDF?rev=HEAD |
http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/*checkout*/nesldoc/presentations/2005_04_IPSN_Heliomote_vr.jh.jf.ppt?rev=HEAD |
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IEEE International Symposium on Information Processing in Sensor Networks (IPSN) |
|
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457 |
462 |
6 |
2005-04-14 |
|
Los Angeles, CA |
IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418eb44b60> |
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| 2004 |
8 |
1 |
Overview of Sensor Networks |
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IEEE Computer |
37 |
8 |
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41 |
49 |
9 |
2004-08-14 |
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true |
true |
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#<DocumentCategory:0x007f418e7738d8> |
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| 2004 |
11 |
3 |
Node-level Energy Management for Sensor Networks in the Presence of Multiple Applications |
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Wireless Networks |
10 |
6 |
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737 |
746 |
9 |
2004-11-14 |
|
Hingham, MA, USA |
Kluwer Academic Publishers |
true |
true |
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#<DocumentCategory:0x007f418e2d6500> |
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| 2003 |
7 |
1 |
Subcarrier Assignment and Bit Loading Algorithms for OFDMA based Wireless Networks |
Orthogonal Frequency Division Multiple Access (OFDMA) is an emerging multiple access technology. In this paper we consider OFDMA in the context of fixed wireless networks. This paper addresses the problem of assigning subcarriers and bits to point-to-point wireless links in the presence of co-channel interference and Rayleigh fading. The objective is to minimize the total transmitted power over the entire network while satisfying the data rate requirement of each link. We formulate this problem as a constrained optimization problem and present centralized algorithms. The simulation results show that our approach results in an efficient assignment of subcarriers and transmitter power levels in terms of the energy required for transmitting each bit of information. However, centralized algorithms require knowledge of the entire network topology and channel characteristics of every link. In a practical scenario that would not be the situation and there is a need for distributed rate allocation algorithms. To address this need, we also present a distributed algorithm for allocating subcarriers and bits in order to satisfy the rate requirements of the links. |
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http://www.ee.ucla.edu/~kulkarni/papers/tmc03.pdf |
http://www.ee.ucla.edu/~kulkarni/papers/tmc03.doc |
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to appear in IEEE Transactions on Mobile Computing |
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31 |
2003-07-14 |
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true |
true |
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#<DocumentCategory:0x007f418eff54c0> |
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| 2005 |
1 |
4 |
Worst- and Best-Case Coverage in Sensor Networks |
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IEEE Transactions on Mobile Computing |
4 |
5 |
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84 |
92 |
9 |
2005-01-14 |
2005-02-14 |
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true |
true |
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#<DocumentCategory:0x007f418f958170> |
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| 2002 |
11 |
1 |
Subcarrier and Bit Allocation Strategies for OFDMA based Wireless Ad Hoc Networks |
Orthogonal Frequency Division Multiple Access
(OFDMA) is an emerging multiple access technology. In this
paper we consider OFDMA in the context of fixed wireless ad hoc
networks. We address the problem of assigning subcarriers and
hits to point-to-pointw ireless links in the presence off o-channel
interference and Rayleigh fading. The objective is to minimize the
total transmitted power over the entire network while satisfying
as B constrained optimization problem and present a heuristic
algorithm. The simulation results show that our algorithm results
in an eflicient assignment of subcarriersa nd transmitter power
levels in terms of the energy required for transmitting each bit of
information. |
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http://www.ee.ucla.edu/~kulkarni/papers/globecom02.pdf |
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IEEE Globecom '02 |
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92 |
96 |
5 |
2002-11-15 |
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Taipei, Taiwan |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418e81f138> |
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| 2005 |
7 |
6 |
Cyclops: In Situ Image Sensing and Interpretation in Wireless Sensor Networks |
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Proceedings of the 3rd ACM Conference on Embedded Networked Sensor Systems (SenSys 2005) |
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0 |
2005-11-29 |
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San Diego, CA |
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true |
true |
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#<DocumentCategory:0x007f418e2aa310> |
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| 2005 |
3 |
11 |
Statistical Properties of Loaded Wireless Multicarrier Systems |
Multicarrier modulation has established itself as an appealing option for high-performance wireless communication systems. When the channel varies slowly in time, such as in applications with low terminal mobility, adaptive loading further enhances the system performance considerably. However, even with adaptive loading, significant performance fluctuations still occur, which impact the higher layers and the overall system behavior. First, a good understanding of the nature of these fluctuations is crucial to design better higher layers that are able to tolerate or combat this variability. For this reason, we develop a full statistical description of a loaded wireless multicarrier system
that accurately characterizes its behavior. Our model abstracts the loaded system as an equivalent single carrier system with flat log-normal fading and has the channel tap as a single parameter. Second, with our model, the physical layer can now be incorporated in an abstracted fashion during simulation, resulting in significant speed-ups. Indeed, the alternative would be to include the entire loaded multicarrier system in these simulations, which is highly time consuming. Third, our statistical model is also important for the mathematical analysis of protocols, which requires knowledge of the physical layer statistics. We derive such statistics for both correlated and uncorrelated Rayleigh fading. |
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http://fleece.ucsd.edu/~curts/papers/TWireless05.pdf |
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IEEE Transactions on Wireless Communications |
4 |
5 |
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2111 |
2120 |
10 |
2005-09-15 |
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true |
true |
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#<DocumentCategory:0x007f418fa0d160> |
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| 2005 |
3 |
12 |
A Radio Aware Routing Protocol for Wireless Mesh Networks |
Wireless Mesh Networks (WMNs) aim to solve the limitations and consequently to improve the performance of ad hoc networks, wireless local area networks (WLANs), and wireless metropolitan area networks (WMANs). A typical WMN consist of mesh routers and mesh clients, where mesh routers have minimal mobility and form the backbone of WMNs. They provide network access for both mesh and conventional clients. Mesh clients can be either stationary or mobile, and can form a client mesh network among themselves and with mesh routers.
In this paper we address an important issue of designing a radio aware routing metric for WMNs. We develop on previous work of routing metric design and propose a new metric based on ETT (Expected Transmission time), which is especially suited for current multi-rate radios and upcoming generation of wireless standards such as 802.11n. We compare our metric with the existing metrics and demonstrate an improved system throughput in typical scenarios.
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http://www.ee.ucla.edu/~kulkarni/papers/routing.pdf |
http://www.ee.ucla.edu/~kulkarni/papers/routing.doc |
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6 |
2005-03-15 |
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true |
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#<DocumentCategory:0x007f418ed1bf60> |
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| 2003 |
8 |
1 |
Energy efficiency and fairness tradeoffs in multi-resource, multi-tasking embedded systems |
This paper presents techniques for optimizing the energy
efficiency of multi-resource, multi-tasking embedded systems.
Low power design of individual system resources, such as
embedded processors, has been extensively studied in the past.
However, system-level techniques, such as those presented in this
paper, which exploit the synergy between various system
resources, achieve levels of energy efficiency that cannot be
obtained by considering individual resources independently. We
demonstrate that, in multi-resource embedded systems that
concurrently execute multiple applications, there exists a tradeoff
between resource management efficiency and resource allocation
fairness. By solving the multi-resource energy optimization
problem in the context of an embedded sensor system, we show
that our techniques enable the system designer to traverse this
efficiency-fairness tradeoff space. |
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http://www.ee.ucla.edu/~vijay/files/islped03.pdf |
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ACM International Symposium on Low Power Electronics and Design |
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469 |
474 |
6 |
2003-08-15 |
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Seoul, South Korea |
ACM Press |
true |
true |
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#<DocumentCategory:0x007f418ef9b038> |
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| 2002 |
10 |
1 |
Distributed On-demand Address Assignment in Wireless Sensor Networks |
Sensor networks consist of autonomous wireless sensor nodes that are networked together
in an ad-hoc fashion. The tiny nodes are equipped with substantial processing capabilities, enabling
them to combine and compress their sensor data. The aim is to limit the amount of network traffic, and
as such conserve the nodes’ limited battery energy. However, due to the small packet payload, the MAC
header is a significant, and energy-costly, overhead. To remedy this, we propose a novel scheme for
MAC address assignment. The two key features which make our approach unique are the exploitation
of spatial address reuse and an encoded representation of the addresses in data packets. To assign the
addresses, we develop a purely distributed algorithm that relies solely on local messsage exchanges.
Other salient features of our approach are the ability to handle unidirectional links and the excellent
scalability of both the assignment algorithm and address representation. In typical scenarios, the MAC
overhead is reduced by a factor of three compared to existing approaches. |
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http://www.ee.ucla.edu/~kulkarni/papers/tpds02.pdf |
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IEEE Transactions on Parallel and Distributed Systems |
13 |
10 |
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1056 |
1065 |
10 |
2002-10-15 |
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IEEE |
true |
true |
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#<DocumentCategory:0x007f418ea15e10> |
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| 2002 |
6 |
4 |
On Communication Security in Wireless Ad-Hoc Sensor Networks |
Networks of wireless microsensors for monitoring physical environments have
emerged as an important new application area for wireless technology.
Key attributes of these new types of networked systems are the severely
constrained computational and energy resources, and an ad hoc operational
environment. This paper is a study of the communication security aspects of
these networks. Resource limitations and specific architecture of sensor networks call for customized security mechanisms. Our approach is to classify the types of data existing in sensor networks, and identify possible communication security threats according to that classification. We propose a communication security scheme where for each type of data we define a corresponding security mechanism. By employing this multitiered security architecture where each mechanism has different resource requirements, we allow for efficient resource management, which is essential for wireless sensor networks.
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http://www.ee.ucla.edu/~tsiatsis/research/pub/wetice02.pdf |
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Eleventh IEEE International Workshop on Enabling Technologies: Infrastructure for Collaborative Enterprises (WETICE), |
1 |
1 |
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139 |
144 |
6 |
2002-06-16 |
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Pittsburgh, Pennsylvania, USA |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418f674940> |
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| 2002 |
6 |
1 |
Dynamic Link Labels for Energy-Efficient MAC Headers in Wireless Sensor Networks |
Sensor data typically consists of packets with small payloads due to which the MAC header is a significant and energy-expensive overhead. We present a scheme that replaces conventional MAC addresses with dynamically assigned short link labels that are spatially reused. This would be useful in self-configuring sensor networks. We also present an encoded representation of these labels for use in data packets. We develop a distributed algorithm involving local exchange of control messages for the assignment of these labels. Simulation results demonstrate the scalability of the assignment algorithm and the encoded label representation. In typical scenarios, the MAC header is reduced by a factor of eight as compared to traditional MAC headers. We also show the conditions under which the energy savings outweigh the protocol overheads. |
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http://www.ee.ucla.edu/~kulkarni/papers/sensors02.pdf |
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IEEE Sensors '02 |
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1520 |
1525 |
6 |
2002-06-15 |
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Orlando, FL |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418eb6b6c0> |
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| 2003 |
6 |
1 |
A survey of techniques for energy efficient on-chip communication |
Interconnects have been shown to be a dominant source of energy
consumption in modern day System-on-Chip (SoC) designs. With
a large (and growing) number of electronic systems being designed
with battery considerations in mind, minimizing the energy consumed
in on-chip interconnects becomes crucial. Further, the use
of nanometer technologies is making it increasingly important to
consider reliability issues during the design of SoC communication
architectures. Continued supply voltage scaling has led to decreased
noise margins, making interconnects more susceptible to
noise sources such as crosstalk, power supply noise, radiation induced
defects, etc. The resulting transient faults cause the interconnect
to behave as an unreliable transport medium for data signals.
Therefore, fault tolerant communication mechanisms, such as Automatic
Repeat Request (ARQ), Forward Error Correction (FEC),
etc., which have been widely used in the networking community,
are likely to percolate to the SoC domain.
This paper presents a survey of techniques for energy efficient
on-chip communication. Techniques operating at different levels
of the communication design hierarchy are described, including
circuit-level techniques, such as low voltage signaling, architecture level
techniques, such as communication architecture selection and
bus isolation, system-level techniques, such as communication based
power management and dynamic voltage scaling for interconnects,
and network-level techniques, such as error resilient encoding for
packetized on-chip communication. Emerging technologies, such
as Code Division Multiple Access (CDMA) based buses, and wireless
interconnects are also surveyed. |
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http://www.ee.ucla.edu/~vijay/dac03_onchip.pdf |
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ACM/IEEE Design Automation Conference |
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900 |
905 |
6 |
2003-06-15 |
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Anaheim, CA |
ACM Press |
true |
true |
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#<DocumentCategory:0x007f418e586480> |
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| 2002 |
8 |
1 |
E^2WFQ: An energy efficient fair scheduling policy for wireless systems |
As embedded systems are being networked, often wirelessly, an
increasingly larger share of their total energy budget is due to the
communication. This necessitates the development of power management
techniques that address communication subsystems, such
as radios, as opposed to computation subsystems, such as embedded
processors, to which most of the research effort thus far has
been devoted. In this paper, we present E2WFQ, an energy effi-
cient version of the Weighted Fair Queuing (WFQ) algorithm for
packet scheduling in communication systems. We employ a recently
proposed radio power management technique, DynamicModulation
Scaling (DMS), as a control knob to enable energy-latency
tradeoffs during wireless packet scheduling. The use of E2WFQ
results in an energy aware packet scheduler, which exploits the
statistics of the input arrival pattern as well as the variability in
packet lengths. Simulation results show that large savings in energy
consumption can be obtained through the use of our scheduling
scheme, compared to conventional WFQ, with only a small,
bounded increase in worst case packet latency. |
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http://www.ee.ucla.edu/~vijay/files/islped02_e2wfq.pdf |
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ACM International Symposium on Low Power Electronics and Design |
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30 |
35 |
6 |
2002-08-15 |
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Monterey, CA |
ACM Press |
true |
true |
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#<DocumentCategory:0x007f418e3d52f8> |
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| 2003 |
8 |
2 |
The N-hop Multilateration Primitive For Node Localization Problems |
The recent advances in MEMS, embedded systems and wireless communication technologies are making the realization and deployment of networked wireless microsensors a tangible task. In this paper we study node localization, a component technology that would enhance the effectiveness and capabilities of this new class of networks. The n-hop multilateration primitive presented here, enables ad-hoc deployed sensor nodes to accurately estimate their locations by using known beacon locations that are several hops away and
distance measurements to neighboring nodes. To prevent error accumulation in the network, node locations are computed by setting up and solving a global non-linear optimization problem. The solution is presented in two computation models, centralized and a fully distributed approximation of the centralized model. Our simulation results show that using the fully distributed model, resource constrained sensor nodes can collectively solve a large non-linear optimization problem that none of the nodes can solve individually. This approach results in significant savings in computation and communication, that allows fine-grained localization to run on a low cost sensor node we have
developed. |
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http://nesl.ee.ucla.edu/pw/NESL/papers/2003/JXX_2003_monet.pdf |
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Mobile Networks and Applications journal |
8 |
4 |
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443 |
451 |
9 |
2003-08-15 |
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ACM / Kluwer Academic Publishers |
true |
true |
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#<DocumentCategory:0x007f418f27c248> |
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| 2002 |
1 |
1 |
High-level synthesis with SIMD units |
This paper presents techniques to integrate the
use of Single Instruction Multiple Data (SIMD) functional units in
a high-level synthesis (HLS) design methodology. SIMD functional
units can be configured to operate in one or more SIMD modes,
in which they process multiple sets of smaller bitwidth operands
in parallel. Conceptually, the use of SIMD functional units enables
HLS to (i) exploit parallelism to a higher degree without using
additional resources, (ii) improve resource utilization by enabling
hardware re-use at a fine-grained level, and (iii) improve energy
efficiency for a given area and/or performance constraint.
We illustrate the issues involved in performing high-level synthesis
with SIMD functional units, and discuss how algorithms
involved in a typical high-level synthesis flow can be enhanced
to result in maximal performance and energy improvements.
These techniques are not restricted to specific high-level synthesis
tools/algorithms, and can be plugged into any generic high-level
synthesis system. Experimental results indicate that, the use of
SIMD units can improve performance by up to 1.9X (average of
1.57X), and simultaneously reduce energy consumption by up to
33.16% (average of 28.03%) compared to well-optimized conventional
designs, with minimal area overheads (average of 2.18%).
The performance improvements can be translated into additional
energy savings, resulting in upto 66.26% (average of 55.88%) energy
reductions. Further, our experiments demonstrate that, the
use of SIMD units in a HLS tool results in a shift in the entire area-delay-
energy tradeoff envelope that can be obtained, to include desirable
parts of the design space (i.e., higher quality designs) that
were hitherto unreachable. |
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http://www.ee.ucla.edu/~vijay/files/vlsi02_simd.pdf |
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IEEE International Conference on VLSI Design / ACM Asia South Pacific Design Automation Conference |
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407 |
413 |
7 |
2002-01-15 |
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Bangalore, India |
IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418f686fa0> |
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| 2004 |
12 |
3 |
Joint End-to-End Scheduling, Power Control and Rate Control in Multi-hop Wireless Networks |
This paper addresses the problem of joint scheduling,
power control and rate control while maximizing end-to-end
data rates in multi-hop wireless networks. Using a “physical
layer” network model that explicitly takes into account
interference due to spatial spectrum reuse, we formulate the
throughput maximization problem as a mixed integer linear
programming problem (MILP). While a MILP based approach
yields an optimal solution, it does not scale well to large
networks. To address this issue, we also present a
computationally efficient water-filling based heuristic.
Simulation results, obtained using our heuristic, highlight several
capacity related tradeoffs that arise in wireless ad-hoc networks.
Prior work only provides either asymptotic results on ad-hoc
network capacity or, at best, techniques for computing loose
upper bounds for throughput in specific instances of networks. |
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http://www.ee.ucla.edu/~kulkarni/papers/globecom04.pdf |
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IEEE Globecom '04 |
|
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3357 |
3362 |
6 |
2004-12-15 |
|
Dallas, TX |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418ee3dd30> |
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| 2005 |
6 |
6 |
Coordinated Static and Mobile Sensing for Environmental Monitoring |
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http://nesl.ee.ucla.edu/fw/kansal/pon_dcoss05.pdf |
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Proceedings of the 1st IEEE International Conference on Distributed Computing in Sensor Systems (DCOSS 2005) |
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403 |
405 |
3 |
2005-06-29 |
2005-07-29 |
Marina del Rey, CA |
Springer Verlag |
true |
true |
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#<DocumentCategory:0x007f418ef20518> |
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Show |
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Destroy |
| 2002 |
9 |
1 |
The Bits and Flops of the N-Hop Multilateration Primitive for Node Localization Problems |
The recent advances in MEMS, embedded systems and wireless communication technologies are making the realization and deployment of networked wireless microsensors a tangible task. Vital to the success of wireless microsensor networks is the ability of microsensors to “collectively perform sensing and computation”. In this paper, we study one of the fundamental challenges in sensor networks, node localization. The collaborative multilateration presented here, enables ad-hoc deployed sensor nodes to accurately estimate
their locations by using known beacon locations that are several hops away and distance measurements to neighboring nodes. To prevent error accumulation in the network, node locations are computed by setting up and solving a global non-linear optimization problem. The solution is presented in two computation models, centralized and a fully distributed approximation of the centralized model. Our simulation results show that using the fully distributed model, resource constrained sensor nodes can collectively solve a large non-linear optimization problem that none of the nodes can solve individually. This approach results in significant savings in computation and communication, that
allows fine-grained localization to run on a low cost sensor node we have developed. |
|
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http://nesl.ee.ucla.edu/pw/NESL/papers/2002/C80_2002_wsna.pdf |
|
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Proceedinsg of the First ACM International Workshop on Sensor Networks and Applications (WSNA 2002) |
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112 |
121 |
10 |
2002-09-15 |
|
Atlanta, Georgia, USA |
ACM Press |
true |
true |
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#<DocumentCategory:0x007f418e7b7290> |
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| 2001 |
12 |
1 |
Adaptive power-fidelity in energy aware wireless embedded systems |
Energy aware system operation, and not just low power hardware, is an important requirement for wireless embedded systems. These systems, such as wireless multimedia terminals or wireless sensor nodes, combine (soft) real-time constraints on computation and communication with requirements of long battery lifetime. In this paper, we present an OS-directed dynamic power management technique for such systems that goes beyond conventional techniques to provide an adaptive power vs. fidelity trade-off. The ability of wireless systems to adapt to changing fidelity in the form of data losses and errors is used to tradeoff against energy consumption. We also exploit system workload variation to proactively manage energy resources by predicting processing requirements. The supply voltage, and clock frequency are set according to predicted computation requirements of a specific task instance, and an adaptive feedback control machanism is used to keep system fidelity (deadline misses) within specifications. We present the theoretical framework underlying our approach in the context of both a static priority-based preemptive task scheduler as well as a dynamic priority based one, and present simulation-based performance analysis that shows that our technique provides large energy savings (up to 76%) with little loss in fidelity (<4%). Further, we describe the implementation of our technique in the eCos real-time operating system (RTOS) running on a StrongARM processor to illustrate the issues involved in enhancing RTOSs for energy awareness. |
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http://www.ee.ucla.edu/~vijay/files/rtss01_dvs.pdf |
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IEEE Real Time Systems Symposium |
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106 |
115 |
10 |
2001-12-15 |
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London, UK |
IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418edfa030> |
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| 2002 |
9 |
3 |
A Channel Assignment Scheme for FDMA based Wireless Ad hoc Networks in Rayleigh Fading Environments |
This paper addresses the problem of allocating
spatially reused frequency channels in ad hoc networks to satisfy
data rate constraints on various links. The data rate requirement
of each link is satisfied by using adaptive modulation. Power
control is used to maintain the required signal to interference
and noise ratio (SINR) in the presence of interference, which is
caused due to frequency reuse. The objective is to minimize the
total transmitted power over the entire network while satisfying
the data rate requirement of each link. We show that this
problem is a hard optimization problem and present a heuristic
algorithm. The simulation results show that our algorithm results
in an efficient assignment of frequencies and transmitter power
levels in terms of the energy required for transmitting each bit of
information. The results also demonstrate that our algorithm
outperforms existing techniques. |
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http://www.ee.ucla.edu/~kulkarni/papers/vtc02.pdf |
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IEEE Fall VTC '02 |
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1082 |
1085 |
4 |
2002-09-15 |
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Vancouver, BC |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418ee61000> |
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| 2001 |
11 |
1 |
Modulation scaling for real-time energy aware packet scheduling |
Portable wireless communication systems operate
on a limited battery supply, and energy efficiency is therefore
crucial. Voltage scaling techniques have been proposed to lower
the energy consumption of embedded processors and real-time
operating systems have incorporated these schemes in their task
scheduling engine. However, the actual data transmission itself
constitutes a major portion of the total energy consumption in
these wireless communication systems. In this paper, we extend
the scaling notion to the realm of wireless communications and
propose a novel technique called modulation scaling to decrease
the energy consumed during data transmission. Modulation
scaling trades off energy consumption against transmission
delay and as such, introduces the concept of energy awareness in
communications. We investigate how modulation scaling can be
exploited to design a dynamic power management engine at the
level of the radio. This engine coordinates the packet
transmission schedule while optimizing energy efficiency. We
demonstrate such a power management module for real-time
traffic and show that it reduces the energy consumption of data
transmissions by up to 50% through smart traffic scheduling. |
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http://www.ee.ucla.edu/~vijay/files/globecom01_dms.pdf |
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IEEE Global Telecommunications Conference |
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3653 |
3657 |
5 |
2001-11-15 |
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San Antonio, TX |
IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418f663c58> |
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| 2001 |
10 |
1 |
Distributed Assignment of Encoded MAC Addresses in Sensor Networks |
In wireless sensor networks, the vast majority of wide-scale traffic
consists of only a few bytes, including all network and application
layer IDs. Therefore, MAC addresses, which are vital in a shared
medium, present major overhead, particularly because they are
traditionally chosen network-wide unique. To tackle this
overhead, we propose a dynamic MAC addressing scheme based
on a distributed algorithm. The assigned addresses are reused
spatially and represented by variable length codewords. Our
scheme scales very well with the network size, rendering it well
suited for sensor networks with thousands or millions of nodes. |
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http://www.ee.ucla.edu/~kulkarni/papers/mobihoc01.pdf |
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Symposium on Mobile Ad Hoc Networking & Computing (MobiHoc'01) |
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295 |
298 |
4 |
2001-10-15 |
|
Long Beach, CA |
ACM |
true |
true |
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#<DocumentCategory:0x007f418d37ec88> |
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| 2004 |
10 |
3 |
Controlled Mobility for Sustainable Wireless Networks |
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http://www.ee.ucla.edu/%7Ekansal/papers/kansal_secon04.pdf |
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IEEE Sensor and Ad Hoc Communications and Networks (SECON) |
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8 |
2004-10-15 |
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Santa Clara, CA |
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true |
true |
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#<DocumentCategory:0x007f418f5c1ca0> |
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| 2004 |
10 |
4 |
Controlled Mobility for Sustainable Wireless Networks |
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http://www.ee.ucla.edu/%7Ekansal/papers/kansal_secon04.pdf |
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IEEE Sensor and Ad Hoc Communications and Networks (SECON) |
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1 |
6 |
7 |
2004-10-15 |
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Santa Clara, CA |
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true |
true |
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#<DocumentCategory:0x007f418fb28b58> |
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| 2005 |
3 |
13 |
Performance Aware Tasking for Environmentally Powered Sensor Networks |
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http://www.ee.ucla.edu/%7Ekansal/papers/kansal_sigmetrics04.pdf |
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ACM Joint International Conference on Measurement and Modeling of Computer Systems (SIGMETRICS) |
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223 |
234 |
12 |
2004-06-15 |
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New York, NY |
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true |
true |
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#<DocumentCategory:0x007f418f4837d0> |
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| 2008 |
4 |
3 |
Peering into Wireless Sensor Networks with LowLog |
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0 |
2008-04-21 |
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false |
true |
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#<DocumentCategory:0x007f418eac6c60> |
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| 2003 |
11 |
2 |
Poster abstract: Spatial average of a continuous physical process in sensor networks |
Wireless ad-hoc sensor networks have caught the fancy of many
researchers through the world in a very small span of time.
Although notable progress has been made in several key areas,
several researchers falter in the way they look at sensor networks
i.e. just another kind of wireless ad hoc networks, albeit one
composed of energy constrained nodes. A key aspect that makes
sensor networks different from traditional networks is their
strong link to the physical world. We develop this perspective
by studying an interesting class of sensor network applications
called aggregation applications.
We argue that when a user queries for aggregates like maximum,
average etc., he is interested in knowing the statistics of the
underlying physical process. In general, this is not equivalent to
the statistics gathered from a bunch of nodes. We introduce a
distinction between aggregates calculated over a region and
aggregates calculated over a discrete set of nodes. We classify
them as spatial and nodal aggregates respectively. Till now,
researchers have followed the approach of doing nodal
aggregation in response to every user query in sensor networks.
For a continuous physical process and a random deployment of
sensor nodes, which are a norm for sensor networks, the
conventional approach of doing nodal aggregation produces
inaccurate results.
We verify our claim by studying a specific aggregation function
namely the average over a region (spatial average) in detail.
We use a voronoi-based approach to propose an algorithm for
calculating spatial average in sensor networks. The algorithm
can work in two modes – centralized and distributed. The energy
and accuracy tradeoff associated with each of the two modes is
analyzed in detail. The efficacy of the proposed algorithm is
tested over a wide variety of physical processes including real
precipitation data of South America acquired over a span of past
50 years. We will show that our algorithm gives a 2-8 times
performance gain as compared to the conventional approach of
doing nodal aggregation. We further explore the robustness of
our algorithm to link failures and channel impairments.
Although not 100% accurate, our approach is a simple, efficient
and a practical solution for calculating the spatial average. We
have implemented our algorithm on Berkeley motes. Our first
prototype implementation occupies less than 12K flash ROM
and consumes less than 1.6K run-time memory. Our algorithm
can be easily integrated with available frameworks for doing
aggregation in sensor networks. For a minimal cost, our
on a network of motes.
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http://www.ee.ucla.edu/~saurabh/publications/Sensysposter03.PDF |
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ACM Conference on Embedded Networked Sensor Systems (SENSYS). |
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0 |
2003-11-15 |
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true |
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#<DocumentCategory:0x007f418ed41dc8> |
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| 2005 |
2 |
4 |
Energy aware wireless systems with adaptive power-fidelity tradeoffs |
Wireless networked embedded systems, such as
multimedia terminals, sensor nodes, etc., present a rich domain
for making energy/performance/quality tradeoffs based on application
needs, network conditions, etc. Energy awareness in these
systems is the ability to perform tradeoffs between available
battery energy and application quality requirements. In this
paper, we show how operating system directed dynamic voltage
scaling and dynamic power management can provide for such
a capability. We propose a real-time scheduling algorithm that
uses runtime feedback about application behavior to provide
adaptive power-fidelity tradeoffs. We demonstrate our approach
in the context of a static priority based preemptive task scheduler.
Simulation results show that the proposed algorithm results in
significant energy savings compared to state-of-the-art dynamic
voltage scaling schemes with minimal loss in system fidelity.
We have implemented our scheduling algorithm into the eCos
real-time operating system running on an Intel XScale based
variable voltage platform. Experimental results obtained using
this platform confirm the effectiveness of our technique. |
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http://www.ee.ucla.edu/~vijay/files/tvlsi05_dvs.pdf |
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IEEE Transactions on VLSI Systems |
13 |
2 |
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211 |
225 |
15 |
2005-02-15 |
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IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418eba0de8> |
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| 2003 |
11 |
3 |
Poster abstract: Density, Accuracy, Delay and Lifetime tradeoffs in sensor networks – A multidimensional design perspective |
With the growing interest in wireless sensor networks, techniques
for their systematic analysis design and optimization are essential.
Despite numerous research efforts in optimizing hardware,
algorithms and protocols for these networks, it remains largely
unexplored how these innovations can be all tied together to
design a sensor network for a specific practical application. We
propose a methodology that starts from four independent quality
of service (QoS) parameters and allows the user to completely and
unambiguously describe the desired performance, without having
to deal with the details of individual devices or protocols. By
making appropriate choices in terms of device capabilities and
run-time techniques, a design can be positioned in this fourdimensional
QoS space. Furthermore, we describe a technique to
explore the associated tradeoffs at design time, using both
analytical expressions and simulations. To illustrate the benefits
of our approach, a design example is worked out, which shows a
five fold improvement in network operational lifetime by adapting
the event reporting delay.
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http://www.ee.ucla.edu/~saurabh/publications/SenSysposter-adlakha.pdf |
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ACM Conference on Embedded Networked Sensor Systems (SENSYS). |
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2003-11-15 |
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true |
true |
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#<DocumentCategory:0x007f418e6cff80> |
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| 2004 |
2 |
2 |
Energy efficient wireless packet scheduling and fair queuing |
As embedded systems are being networked, often wirelessly, an increasingly larger share of their total energy budget is due to the communication. This necessitates the development of power management techniques that address communication subsystems, such as radios, as opposed to computation subsystems, such as embedded processors, to which most of the research effort thus far has been devoted. In this paper, we present techniques for energy efficient packet scheduling and fair queuing in wireless communication systems. Our techniques are based on an extensive slack management approach that dynamically adapts the output rate of the system in accordance with the input packet arrival rate. We use a recently proposed radio power management technique, dynamic modulation scaling (DMS), as a control knob to enable energy-latency trade-offs during wireless packet transmission. We first analyze a single input stream scenario,
and describe a rate adaptation technique that results in significantly lower energy consumption (reductions of up to 10x), while still bounding the resulting packet delays. By appropriately setting the various parameters of our algorithm, the system can be made to traverse the energy-latency-fidelity trade-off space. We extend our techniques to a multiple input stream scenario, and present
E2WFQ, an energy efficient version of the weighted fair queuing (WFQ) algorithm for fair packet scheduling. Simulation results show that large energy savings can be obtained through the use of E2WFQ, with only a small, bounded increase in worst case packet latency. Further, our results demonstrate that E2WFQ does not adversely affect the throughput allocation (and hence, fairness) of WFQ. |
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http://www.ee.ucla.edu/~vijay/files/tecs04_wfq.pdf |
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ACM Transactions on Embedded Computing Systems |
3 |
1 |
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3 |
23 |
21 |
2004-02-15 |
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ACM Press |
true |
true |
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#<DocumentCategory:0x007f418f6e6ba8> |
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| 2005 |
3 |
14 |
Call and Response: Experiments in Sampling the Environment |
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http://www.ee.ucla.edu/%7Ekansal/papers/batalin_sensys04.pdf |
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ACM Sensys |
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25 |
38 |
15 |
2004-11-15 |
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Baltimore, Maryland |
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true |
false |
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#<DocumentCategory:0x007f418ec999e8> |
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| 2004 |
6 |
5 |
Fidelity and Resource Sensitive Data Gathering |
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http://www.ee.ucla.edu/%7Ekansal/papers/pandya_allerton04.pdf |
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42nd Allerton Conference |
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8 |
2004-06-15 |
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Allerton, IL |
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true |
true |
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#<DocumentCategory:0x007f418e728900> |
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| 2004 |
10 |
5 |
Lossy Source Coding of Multiple Gaussian Sources: m-helper problem |
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http://www.ee.ucla.edu/%7Ekansal/papers/pandya_itw04.pdf |
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IEEE Information Theory Workshop (ITW) |
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34 |
38 |
8 |
2004-10-15 |
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San Antonio,TX |
|
true |
false |
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#<DocumentCategory:0x007f418f2ff828> |
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| 2003 |
8 |
4 |
An Environmental Energy Harvesting Framework for Sensor Networks |
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http://www.ee.ucla.edu/~kansal/papers/kansal_islped03.pdf |
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ACM/IEEE Int'l Symposium on Low Power Electronics and Design (ISLPED) |
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481 |
486 |
6 |
2003-08-15 |
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Seoul, Korea |
|
true |
true |
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#<DocumentCategory:0x007f418e3426b0> |
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| 2003 |
7 |
2 |
An Overview of Delay Jitter Control for Packet Audio in IP-Telephony |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_iete_scan.PDF |
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IETE Technical Review, |
20 |
4 |
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10 |
2003-07-15 |
2003-08-15 |
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true |
false |
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#<DocumentCategory:0x007f418f1b14f8> |
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Show |
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Destroy |
| 2004 |
2 |
3 |
Energy efficient wireless packet scheduling and fair queuing |
As embedded systems are being networked, often wirelessly, an increasingly larger share of their total energy budget is due to the communication. This necessitates the development of power management techniques that address communication subsystems, such as radios, as opposed to computation subsystems, such as embedded processors, to which most of the research effort thus far has been devoted. In this paper, we present techniques for energy efficient packet scheduling and fair queuing in wireless communication systems. Our techniques are based on an extensive slack management approach that dynamically adapts the output rate of the system in accordance with the input packet arrival rate. We use a recently proposed radio power management technique, dynamic modulation scaling (DMS), as a control knob to enable energy-latency trade-offs during wireless packet transmission. We first analyze a single input stream scenario,
and describe a rate adaptation technique that results in significantly lower energy consumption (reductions of up to 10x), while still bounding the resulting packet delays. By appropriately setting the various parameters of our algorithm, the system can be made to traverse the energy-latency-fidelity trade-off space. We extend our techniques to a multiple input stream scenario, and present
E2WFQ, an energy efficient version of the weighted fair queuing (WFQ) algorithm for fair packet scheduling. Simulation results show that large energy savings can be obtained through the use of E2WFQ, with only a small, bounded increase in worst case packet latency. Further, our results demonstrate that E2WFQ does not adversely affect the throughput allocation (and hence, fairness) of WFQ. |
|
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http://www.ee.ucla.edu/~vijay/files/tecs04_wfq.pdf |
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ACM Transactions on Embedded Computing Systems |
3 |
1 |
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3 |
23 |
21 |
2004-02-15 |
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ACM Press |
true |
true |
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#<DocumentCategory:0x007f418da183c8> |
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| 2003 |
8 |
3 |
Power management for energy-aware communication systems |
System-level power management has become a key technique to render modern wireless communication devices economically viable. Despite their relatively large impact on the system energy consumption, power management for radios has been limited to shutdown-based schemes, while processors have benefited from superior techniques based on dynamic voltage scaling (DVS). However, similar scaling approaches that trade-off energy versus performance are also available for radios. To utilize these in radio power management, existing packet scheduling policies have to be thoroughly rethought to make them energy-aware, essentially opening a whole new set of challenges the same way the introduction of DVS did to CPU task scheduling. We use one specific scaling technique, dynamic modulation scaling (DMS), as a vehicle to outline these challenges,
and to introduce the intricacies caused by the nonpreemptive nature of packet scheduling and the time-varying wireless channel. |
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http://www.ee.ucla.edu/~vijay/files/tecs03_dpm.pdf |
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ACM Transactions on Embedded Computing Systems |
2 |
3 |
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431 |
447 |
17 |
2003-08-15 |
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ACM Press |
true |
true |
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#<DocumentCategory:0x007f418e522f70> |
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Show |
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| 2002 |
3 |
1 |
Energy-aware wireless microsensor networks |
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http://www.ee.ucla.edu/~vijay/files/sp02_wsn.pdf |
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IEEE Signal Processing Magazine |
19 |
2 |
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40 |
50 |
11 |
2002-03-15 |
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IEEE Press |
true |
true |
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#<DocumentCategory:0x007f418e4adfe0> |
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Show |
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| 2004 |
5 |
1 |
Energy efficient design of wireless sensor nodes |
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http://www.ee.ucla.edu/~vijay/files/bookchap04_wsn.pdf |
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Wireless Sensor Networks (C. S. Raghavendra, K. M. Sivalingam and T. Znati - Editors), ISBN 1-4020-7883-8 |
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0 |
2004-05-15 |
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Kluwer Academic Publishers |
false |
true |
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#<DocumentCategory:0x007f418e3d8958> |
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| 2004 |
1 |
1 |
Reconfigurable Fabric: An enabling technology for pervasive medical monitoring |
In the past few years exciting advances in the development of
pervasive computing technologies have taken place, in particular
the field of flexible electronics is emerging: electronic components
such as transistors and wires can be built on a thin flexible
material, and polymer wires can be made to be flexible and
durable. These technologies offer the opportunity to weave
computation, storage, and communication into the fabric of the
very clothing that we wear, thereby creating an intelligent fabric
(also called electronic textiles or e-textiles). The implications of seamlessly integrating a large number of communicating computation and storage resources, mated with sensors and actuators, in close proximity to the human body are
quite exciting. This paper presents the motivation for the
Reconfigurable Fabric (RFab) project underway at UCLA.
Reconfigurability on multiple architectural levels is critical for
intelligent fabrics. Because the wires used for communication and
energy distribution are woven into the garment, an intelligent
garment needs to be able to find new interconnection pathways
when the garment is damaged so that operation can continue. In
addition, reconfiguration at the link layer can allow the creation
of interconnection topologies that are well-suited to performing a
particular computation. Reconfigurability is also needed at the
system level in order to allow the computational load to be
balanced over the available computational units. This paper
discusses the system architecture of the RFab-Vest, a pervasive
medical monitoring jacket, the design decisions that led to it, and
describes the first complete RFab-Vest prototype. |
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http://www.ee.ucla.edu/~vijay/files/cnds04_rfab.pdf |
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Communication Networks and Distributed Systems Modeling and Simulation Conference |
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6 |
2004-01-15 |
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San Diego |
Society for Modeling and Simulation International |
true |
true |
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#<DocumentCategory:0x007f418e2df498> |
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Show |
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| 2002 |
7 |
1 |
Channel Allocation for OFDMA based Wireless Ad-hoc Networks |
Wireless ad hoc networks find great utility in situations where there is no wired base station
infrastructure. For large networks wireless channel access needs to be performed in a distributed manner.
Orthogonal Frequency Division Multiple Access (OFDMA) is an emerging multiple access technique that
is used in several new networking technologies. In this paper we study the use of OFDMA for ad hoc
networks. Each point-to-point link does not transmit over the entire band and uses a subset of the total
number of available subcarriers. This enables flexible network resource management with the ability to
vary the output link capacity depending on the traffic load. Specifically, we address the problem of
subcarrier allocation for point-to-point links of ad hoc networks. We present a distributed algorithm for
subcarrier allocation and compare its performance to a centralized graph-theoretic heuristic. The simulation
results also show that our protocol is robust and scalable. |
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http://www.ee.ucla.edu/~kulkarni/papers/spie02.pdf |
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SPIE International Conference on Advanced Signal Processing Algorithms, Architectures, and Implementations |
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10 |
2002-07-15 |
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Seattle, WA |
SPIE |
true |
true |
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#<DocumentCategory:0x007f418cec1ce0> |
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| 2001 |
8 |
2 |
Architecture strategies for energy-efficient packet forwarding in wireless sensor networks |
The energy-efficient communication among wireless sensor nodes determines the
lifetime of a sensor network and exhibits patterns highly dependable on the
sensor application and networking software. This software is responsible for
processing the sensor data and disseminating the data to other nodes or a
central repository. In this paper we propose a node architecture that takes
advantage of both the intelligence of the radio hardware and the needs of
applications to efficiently handle the packet forwarding. It exploits
principles widely used in modern firewall network architectures and as our
analysis shows achieves considerable energy savings.
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http://www.ee.ucla.edu/~tsiatsis/research/pub/islped01.pdf |
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Proceedings on International Symposium on Low Power Electronics and Design (ISLPED), |
1 |
1 |
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92 |
95 |
4 |
2001-08-16 |
2001-08-16 |
Huntington Beach, California, Un |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418f51f900> |
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| 2003 |
3 |
2 |
Motion Constraint Based Handoff Protocol for Mobile Internet |
A major requirement for the mobile Internet is the
wireless network access for handheld personal devices. As an
alternative to the expensive 3G networks, which share 2 Mbps in
several square kilometers, the use of short-range wireless
technologies like Bluetooth (sharing 1 Mbps among just 7 users),
has been proposed. This is much more economical as it works in
the unlicensed band and leverages the existing wired broadband
infrastructure. In such a Bluetooth network, however, the
mobiles will move out from the range of one access point into that
of another more frequently, requiring seamless handoff. We
discuss a new algorithm to support fast handoff at the wireless
layer. Our method exploits the continuity of the user’s path and
existing connection information at the older access point to
reduce the handoff delay. It inter-works with IP micromobility
protocols, such as Cellular IP, for managing other mobility
related issues at layer 3. Simulations reveal that our proposed
method reduces the handoff delay by more than an order of
magnitude and significantly enhances the bandwidth utilization.
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http://www.ee.ucla.edu/~kansal/papers/kansal_wcnc03.pdf |
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IEEE Wireless Communications and Networking Conference (WCNC) |
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1224 |
1229 |
6 |
2003-03-15 |
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IEEE |
true |
false |
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#<DocumentCategory:0x007f418fb6a468> |
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| 2002 |
6 |
2 |
A Handoff Protocol for Mobility in Bluetooth Public Access |
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http://www.ee.ucla.edu/%7Ekansal/thesisMS.pdf |
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Master's Thesis |
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81 |
2002-06-15 |
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true |
false |
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#<DocumentCategory:0x007f418fb0d6a0> |
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| 2002 |
12 |
1 |
Handoff Protocol for Bluetooth Public Access |
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http://www.ee.ucla.edu/~kansal/papers/kansal_icpwc02.pdf |
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IEEE International Conference on Personal Wireless Communications (ICPWC) |
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159 |
162 |
4 |
2002-12-15 |
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true |
false |
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#<DocumentCategory:0x007f418f883da8> |
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| 2005 |
3 |
15 |
A rapid handoff protocol for mobility in Bluetooth public access networks |
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http://portal.acm.org/citation.cfm?id=838204&coll=ACM&dl=GUIDE&CFID=12323230&CFTOKEN=56971003 |
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Fifteenth International Conference on Computer Communication (ICCC'02) |
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787 |
801 |
15 |
2002-08-15 |
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true |
false |
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#<DocumentCategory:0x007f418fad2ca8> |
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| 2002 |
5 |
1 |
Mobility support for Bluetooth public access |
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http://www.ee.ucla.edu/~kansal/papers/kansal_iscas02.pdf |
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IEEE International Symposium on Circuits and Systems (ISCAS) |
5 |
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725 |
728 |
4 |
2002-05-15 |
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true |
false |
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#<DocumentCategory:0x007f418fa71bb0> |
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| 2001 |
11 |
2 |
Adaptive delay adjustment for low jitter audio over Internet |
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http://www.ee.ucla.edu/~kansal/papers/kansal_globecom01.pdf |
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IEEE Globecom |
4 |
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2591 |
2594 |
4 |
2001-11-15 |
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true |
false |
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#<DocumentCategory:0x007f418fa3ca78> |
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| 2001 |
8 |
1 |
Jitter free Audio Playout over Best Effort Packet Networks |
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ATM Forum International Symposium on Broadband Communication in the New Millennium |
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4 |
2001-08-15 |
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true |
false |
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#<DocumentCategory:0x007f418fc33020> |
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| 2002 |
1 |
2 |
Optimizing Sensor Networks in the Energy-Latency-Density Design Space |
In wireless sensor networks, energy efficiency is crucial to achieve
satisfactory network lifetime. To reduce the energy consumption significantly,
a node should turn off its radio most of the time, except when it has to
participate in data forwarding. We propose a new technique, called Sparse
Topology and Energy Management (STEM), which efficiently wakes up nodes from a
deep sleep state without the need for an ultra low-power radio. The designer
can trade off the energy efficiency of this sleep state for the latency
associated with waking up the node. In addition, we integrate STEM with
approaches that also leverage excess network density. We show that our hybrid
wakeup scheme results in energy savings of over two orders of magnitude compared
to sensor networks without topology management. Furthermore, the network
designer is offered full flexibility in exploiting the energy-latency-density
design space, by selecting the appropriate parameter settings of our protocol.
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http://www.ee.ucla.edu/~tsiatsis/research/pub/tmc02.pdf |
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IEEE Transactions on Mobile Computing |
1 |
1 |
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70 |
80 |
11 |
2002-01-16 |
2002-03-16 |
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IEEE |
true |
false |
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#<DocumentCategory:0x007f418fc09900> |
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| 2002 |
6 |
3 |
Topology Management for Sensor Networks: Exploiting Latency and Density |
In wireless sensor networks, energy efficiency is crucial to achieve
satisfactory network lifetime. In order to reduce the energy consumption of a
node significantly, its radio needs to be turned off. Yet, some nodes have to
participate in multi-hop packet forwarding. We tackle this issue by exploiting
two degrees of freedom in topology management: the path setup latency and the
network density. First, we propose a new technique called Sparse Topology and
Energy Management (STEM), which aggressively puts nodes to sleep. It provides a
method to wake up nodes only when they need to forward data, where latency is
traded off for energy savings. Second, STEM integrates efficiently with
existing approaches that leverage the fact that nearby nodes can be equivalent
for traffic forwarding. In this case, an increased network density results in
more energy savings. We analyze a hybrid scheme, which takes advantage of both
setup latency and network density to increase the nodes' lifetime. Our results
show improvements o f nearly two orders of magnitude compared to sensor networks
without topology management.
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http://www.ee.ucla.edu/~tsiatsis/research/pub/mobihoc02.pdf |
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International Symposium on Mobile Ad Hoc Networking & Computing (MobiHoc'02) |
1 |
1 |
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135 |
145 |
11 |
2002-06-16 |
2002-06-16 |
Lausanne, Switzerland |
ACM Press |
true |
false |
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#<DocumentCategory:0x007f418e9ac4b0> |
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| 2002 |
3 |
2 |
STEM: Topology Management for Energy Efficient Sensor Networks |
In wireless sensor networks, where energy efficiency is the key design
challenge, the energy consumption is typically dominated by the node's
communication subsystem. It can only be reduced significantly by transitioning
the embedded radio to a sleep state, at which point the node essentially
retracts from the network topology. Existing topology management schemes have
focused on cleverly selecting which nodes can turn off their radio, without
sacrificing the capacity of the network. We propose a new technique, called
Sparse Topology and Energy Management (STEM), that dramatically improves the
network lifetime by exploiting the fact that most of the time, the network is
only sensing its environment waiting for an event to happen. By alleviating the
restriction of network capacity preservation, we can trade off extensive energy
savings for an increased latency to set up a multi-hop path. We will also show
how STEM integrates efficiently with existing topology management techniques.
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http://www.ee.ucla.edu/~tsiatsis/research/pub/aerospace02.pdf |
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EEE Aerospace Conference |
3 |
1 |
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1099 |
1108 |
10 |
2002-03-16 |
2002-03-16 |
Big Sky, MT |
IEEE |
true |
false |
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| 2006 |
9 |
6 |
GNU Radio 802.15.4 En- and Decoding |
The IEEE wireless standard 802.15.4 gets widespread attention
because of its adoption in sensor networks, home
automation, and other networked systems. The goal of the
project is to implement an en- and decoding block for the
IEEE 802.15.4 protocol in GNU Radio, an open source solution
for software defined radios. This report will give an
insight into the working of GNU Radio and some of its hardware
components. Additionally, it gives details about the
implementation of the en- and decoding blocks. At the end,
we will verify the implementation by sending and receiving
messages to and from an actual IEEE 802.15.4 radio
chip, the CC2420 from ChipCon, and give a small bandwidth
comparison of the two solutions. |
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http://nesl.ee.ucla.edu/fw/thomas/thomas_project_report.pdf |
http://www.cgran.org/browser/projects/ucla_zigbee_phy/trunk |
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2006-09-21 |
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Los Angeles |
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| 2013 |
4 |
3 |
Minimax Control For Cyber-Physical Systems under Network Packet Scheduling Attacks |
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2nd Conference on High Confidence Networked Systems (HiCoNS) at CPS Week 2013 |
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8 |
2013-04-01 |
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Philadelphia, PA |
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#<DocumentCategory:0x007f418ebd4fa8> |
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| 2003 |
4 |
1 |
On the Interaction of Network Characteristics and Collaborative Target Tracking in Sensor Networks |
System-wide energy efficiency is the main driving force of the current
sensor network research. Energy efficiency is highly application-specific
and as a result designing a sensor network algorithm is also performed
under the constraints of a specific application such as latency and
accuracy. In this paper we consider one such sensor network application,
namely collaborative target tracking using acoustic sensors. This
algorithm is an application of a traditional signal processing algorithm
on a sensor network. Traditional target tracking disregards the
underlying sensor measurement transport mechanism and focuses on the
algorithm performance (tracking accuracy) based on parameters such as
the number of trackers. Moreover the timing constraints of target
tracking combined with the nature of the underlying network (wireless,
multi-hop) which drops or delays measurements introduces run time energy,
latency and accuracy tradeoffs. In this paper we study the performance
tradeoff among the three above-mentioned metrics when we vary algorithm
parameters such as the number of trackers and the measurement rate.
We find that we can achieve up to 20% error reduction by introducing
latencies up to 60ms for the a fixed energy consumption. We give
directions about how to exploit directly measurable quantities such
as packet receive rate to adaptively change the latency that achieves
a specific level of accuracy. We also show that in such systems processing
energy is dominating communication energy thus hinting the need for
node diversity and hierarchy.
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NESL TR |
1 |
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12 |
2003-04-16 |
2003-04-16 |
Los Angeles, CA, USA |
NESL |
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| 2005 |
3 |
16 |
Distributed Algorithm and Protocol for Infrastructure-less Navigation and Software Services for Multi Robot Platform |
Autonomous multi-robot systems with various applications in area of mobile sensor network, distributed robotics and robot gaming have become an active area of research. One of the research problems in this area is how to navigate a mobile robot team in an unknown environment without setting up any infrastructure for localization. This kind of scenarios arises when mobile robot team needs to be deployed in ad-hoc fashion in an indoor environment or on a different planet such as Mars. This research problem is formally defined as infrastructure-less navigation problem in this work. One approach to solve this problem is to assign role of landmark to some of the robots while other robots can localize themselves with respect to these landmarks. For this approach and for a system using trilateration as basic localization technique, we define minimum requirements about the initial geometric configuration of a robot team. The required geometric configuration is defined as Navigation Graph. A provably correct distributed algorithm for infrastructure-less robot team navigation is presented. Design of a distributed protocol implementing the proposed algorithm is described. The protocol is implemented in QualNet [17] network simulator.
This thesis also presents design of software platform and services for Ragobot, a multi-robot platform aimed at distributed robotics and mobile sensing research, robotics education, and multi-robot game development.
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http://www.ee.ucla.edu/~parixit/Parixit-Thesis-Winter2005.pdf |
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UCLA Thesis |
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2005-03-16 |
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Los Angeles |
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false |
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#<DocumentCategory:0x007f418f33a7e8> |
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| 2005 |
4 |
1 |
Energy Harvesting Aware Power Management |
This chapter presents an overview of various energy harvesting methods and discusses how appropriate modelling of the harvesting source can help optimize the performance of a distributed system using the harvested energy. |
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http://nesl.ee.ucla.edu/fw/kansal/Ch9_kansal_text_only.pdf |
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Wireless Sensor Networks: A Systems Perspective, Eds. N Bulusu and S Jha |
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10 |
2005-04-06 |
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Artech House |
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| 2005 |
4 |
2 |
Secure Event Reporting Protocol for Sense-response Applications |
Sense-response applications are widely being used for safeguarding critical infrastructure. In such applications, the sensor nodes detect and report events of interest to the base-station which promptly responds with a physical response. A concern that arises immediately is regarding the ability of the sensor nodes to encounter malicious entities that benefit from any form of damage to the critical infrastructure. Due to the lack of physical security and tamper resistant hardware around the sensor nodes, adversaries can easily compromise them, recover their embedded cryptographic material, and subsequently make them pose as authorized nodes in the network. Such compromised nodes can now launch an attack on the network to either suppress the reporting of genuine events or inject false events to the base-station, thereby rendering the entire system useless.
We describe a Secure Event Reporting Protocol (SERP) for sense-response applications which ensures the generation and delivery of valid event reports in the presence of internal attacks launched by compromised nodes within the network. SERP exploits the redundancy and the mutual oversight within a group of nodes triggered by an event to generate an event report which is authenticated by a subset of these nodes. The protocol depends upon the presence of pairwise cryptographic keys between two nodes detecting a common event. We also propose a scalable post deployment mechanism for establishing these keys in the network. Our scheme exploits the Physical Attributes of the sensor nodes for Key Establishment and is referred to as PAKE. We have developed a prototype implementation of SERP and PAKE mechanisms for Mica2 motes and conducted several experiments to evaluate the overall system resiliency to attacks by internally compromised nodes. The obtained results show that SERP generates event report securely and efficiently.
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http://www.ee.ucla.edu/~saurabh/publications/Tech_Report_Serp_pake.pdf |
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Technical report |
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2005-04-06 |
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| 2005 |
4 |
3 |
Coordinated Actuation for Sensing Uncertainty Reduction |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_ipsn.html |
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ACM/IEEE IPSN 2005 demonstration Abstracts |
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2 |
2005-04-06 |
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Los Angeles, CA |
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#<DocumentCategory:0x007f418f28f910> |
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| 2008 |
10 |
1 |
Compressing Trace Logs for Monitoring and Debugging of Embedded Networked Systems |
Understanding the flow of execution within deployed networked and embedded systems. This work explores techniques to generate compressed call trace logs that allow external observers to monitor the runtime behavior of deployed systems. |
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http://nesl.ee.ucla.edu/fw/documents/posters/2009/shea08low.pdf |
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CENS Anual Research Review |
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2008-10-03 |
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UCLA |
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| 2005 |
4 |
4 |
Routing in Wireless Ad hoc Networks: Wireless & Mechanical Data Transfer |
Recent research has shown that using a mobile element to carry data mechanically in a wireless ad hoc network has many advantages over static multihop routing. These works can be broadly classified into two classes. The mobile element acts as a data sink collecting data being generated at the static nodes. This specifically applies to sensor networks. Alternately, the mobile element is used to route data from one part of the network to another. In this paper, we present a routing protocol, where data can travel wirelessly through multihop, or can be mechanically carried by the mobile element(s). The decision is made at runtime, depending on application requirements. Also, we investigate use of two types of mobile elements in our system: those whose motion can be predicted, and those whose motion can be controlled. For the controlled mobile elements, we propose and evaluate some scheduling heuristics. |
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http://www.ee.ucla.edu/~arun/wdtn_arun_mani_bill.pdf |
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SUBMITTED to Workshop on delay tolerant networking and related networks (WDTN-05) |
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2005-04-07 |
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| 2005 |
6 |
3 |
SOS: A dynamic operating system for sensor networks |
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http://nesl.ee.ucla.edu/projects/sos/publications/sos_mobisys_05_talk.ppt |
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2005-06-26 |
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#<DocumentCategory:0x007f418f1a0ae0> |
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| 2005 |
7 |
1 |
A New Light Sensing Module for Mica Motes |
We present the Illumimote, a new light sensing module for the Mica mote platform. The Illumimote achieves performance comparable to a commercial light intensity meter, while conforming to the size and energy constraints imposed by its application in wireless sensor networks. The Illumimote was developed to replace the Mica sensor board (MTS310) whose slow response time and narrow dynamic range in light intensity capture is unsuitable to many applications, including media production. The Illumimote features significantly improved SNR due to its adoption of high-end photo sensors, amplification and conversion circuits coupled with active noise suppression, application-tuned filter networks, and a noise-attentive manual layout. Unlike the MTS310, the Illumimote can capture RGB color intensity (for color temperature calculation) and incident light angle (which discerns the angle of ray arrival from the strongest source). Our prototype demonstrated significantly faster response time (> 6x) and a much wider dynamic range (> 10x) in light intensity measurement as compared with the MTS310. The light-angle estimation results were well correlated with an average error of just 2.63 degree. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2005/Illumimote_Sensors2005_HeeminPark.pdf |
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The 4th IEEE Conference on Sensors |
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2005-10-12 |
2005-11-12 |
Irvine, CA |
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#<DocumentCategory:0x007f418f0ff988> |
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| 2005 |
4 |
6 |
Coordinated Actuation for Sensing Uncertainty Reduction |
Motility can improve sensor coverage in several ways and this poster summarizes our work in this domain. |
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http://nesl.ee.ucla.edu/fw/kansal/PosterIPSN05.pdf |
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ACM/IEEE IPSN 2005 |
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2005-04-03 |
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#<DocumentCategory:0x007f418f0ae740> |
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| 2005 |
6 |
1 |
On sensor Network Lifetime and Data Distortion |
Fidelity is one of the key considerations in data collection schemes for sensor networks. A second important consideration is the energy expense of achieving that fidelity. Data from multiple correlated sensors is collected over multihop
routes and fused to reproduce the phenomenon. However, the same distortion may be achieved using multiple rate allocations among the correlated sensors. These rate allocations would typically have different energy cost in routing depending on the network topology. We consider the interplay between these
two considerations of distortion and energy. First, we describe
the various factors that affect this trade-off. Second, we discuss bounds on the achievable performance with respect to this tradeoff. Specifically, we relate the network lifetime, L_t to the distortion D of the delivered data. Finally, we present low-complexity approximations for the efficient computation of the L_t(D) bound. |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_isit05.pdf |
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IEEE International Symposium on Information Theory (ISIT) |
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6 |
10 |
5 |
2005-09-23 |
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Adelaide, Australia |
IEEE |
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true |
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#<DocumentCategory:0x007f418f0a5208> |
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| 2005 |
6 |
2 |
Acquiring Medium Models for Sensing Performance Estimation |
The quality of sensing in practical sensor network deployments
su®ers due to the presence of obstacles in the sensing medium. If
such unknown obstacles are present, and the sensor data indicates
that no targets of interest are detected, then there is no easy way for
the application to distinguish between the cases that there really is
no target or that the targets are located in occluded regions. The
obstacles may not be known before deployment and may change over
time. Hence, it is of interest to develop methods which enable a sensor
network to determine the presence and extent of sensing occlusions.
We present one such method based on the use of a range sensor to
map the obstacles in the medium. A network architecture to support
e±cient medium mapping facilities is presented, along with several
design choices in the acquisition and update of the medium map data.
We also present algorithms to rapidly acquire this data and share it
among multiple nodes. All algorithms presented are implemented on
prototype hardware consisting of an actuated laser and an embedded
processing platform. |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_secon05.pdf |
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IEEE Sensor and Ad Hoc Communications and Networks (SECON) |
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12 |
2005-09-23 |
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Santa Clara, CA |
IEEE/ACM |
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#<DocumentCategory:0x007f418f0800e8> |
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| 2005 |
4 |
7 |
Time Synchronization in Sensor Networks |
This chapter presents an overview of the time syncrhonization problem in sensor networks. It briefly discusses the existing solutions in this domain and conclude with presenting challenges for future research. |
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In Wireless Sensor Networks: A Systems Perspective, Eds. N Bulusu and S Jha |
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10 |
2005-04-12 |
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Artech House |
true |
true |
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#<DocumentCategory:0x007f418f033090> |
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| 2005 |
6 |
4 |
Rate-adaptive time synchronization for long-lived sensor networks |
Time synchronization is critical to sensor networks at many layers
of its design and enables better duty-cycling of the radio, accurate
localization, beamforming and other collaborative signal
processing. While there has been significant work in sensor
network synchronization, measurement based studies have been
restricted to very short-term (few minutes) datasets and have
focused on obtaining accurate instantaneous synchronization.
Long-term synchronization has typically been handled by periodic
re-synchronization schemes with beacon intervals of a few
minutes based on the assumption that long-term drift is too hard
to model and predict. Thus, none of this work exploits the
temporally correlated behavior of the clock drift. Yet, there are
incredible energy gains to be achieved from better modeling and
prediction of long-term drift that can provide bounds on longterm
synchronization error across a sensor network. Better
synchronization can lead to significantly lower duty-cycles of the
radio, simplify signal processing and can enable an order of
magnitude greater lifetime than current techniques.
We measure, evaluate and analyze in-depth the long-term
behavior of synchronization skew and drift on typical Mica sensor
nodes and develop an efficient long-term time synchronization
protocol. We use four real time data sets gathered over periods of
12-30 hours in different environmental conditions to study the
interplay between three key parameters that influence long-term
synchronization – synchronization rate, history of past
synchronization beacons and the estimation scheme. We use this
measurement-based study to design an online adaptive timesynchronization
algorithm that can adapt to changing clock drift
and environmental conditions while achieving applicationspecified
precision with very high probability. We find that our
algorithm achieves between one and two orders of magnitude
improvement in energy efficiency over currently available time synchronization approaches. |
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http://portal.acm.org/citation.cfm?id=1064212.1064261 |
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Proceedings of ACM SIGMETRICS international conference on measurement and modeling in computer (Short Paper) |
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374 |
375 |
2 |
2005-06-12 |
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Alberta, Canada |
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#<DocumentCategory:0x007f418f005f78> |
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| 2005 |
7 |
2 |
Estimating clock uncertainty for efficient duty-cycling in sensor networks |
Radio duty cycling has received significant attention in sensor
networking literature, particularly in the form of protocols for medium
access control and topology management. While many protocols have
claimed to achieve significant duty-cycling benefit in theory and
simulation, these benefits have often not translated to practice. The
dominant factor that prevents the optimal usage of the radio in real
deployment settings is time uncertainty between sensor nodes. This
paper proposes an uncertainty-driven approach to duty-cycling where a
model of long-term clock drift is used to minimize duty-cycling
overhead. First, we use long-term empirical measurements to evaluate
and analyze in-depth the interplay between three key parameters that
influence long-term synchronization - synchronization rate, history of
past synchronization beacons and the estimation scheme. Second, we use
this measurement-based study to design a rate-adaptive,
energy-efficient long-term time synchronization algorithm that can
adapt to changing clock drift and environmental conditions while
achieving application-specified precision with very high probability.
Finally, we integrate our uncertainty-driven time-synchronization
scheme with a MAC layer protocol, BMAC, and empirically demonstrate one to two orders of magnitude improvement in network lifetime with
negligible loss of network throughput.
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To appear in the Third ACM Conference on Sensor Networking Systems (SenSys) |
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2005-11-12 |
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#<DocumentCategory:0x007f418efdd078> |
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| 2005 |
8 |
1 |
Packet Delivery Performance for On-Body Mica2dot Wireless Sensor Networks |
Wearable computing continues to attract researchers’ interests. In particular, the combination of biomedical applications and sensor networks has been in major focus, especially in the field of real-time health care monitoring. Various connection mediums have been proposed for such platforms. This includes wired and wireless communication schemes. The inconvenience of interconnecting sensors through wires, however, not only induces high maintenance costs, but also may limits the freedom of human activity. Utilizing wireless biosensors nodes removes such unnatural wire constraints. Yet, employing wireless sensors in the close proximity to the human body may introduce a new set of limitations. The goal of this work is to study how the human body affects the quality of the wireless links between nodes. Unlike wire connections, wireless connections are unstable and vulnerable to noise from environment. Throughout our experiments, we attach sensor nodes to different parts of the body and monitor the packet reception rate between various nodes. We envision that the experimental results can be used to assist designers construct reliable and efficient wireless wearable computing setups for related biomedical studies. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/nesldoc/posters/2005_08_SECON05_PosterAbstract_DJea.pdf |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/nesldoc/posters/2005_08_SECON05_Poster_DJea.pdf |
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Second Annual IEEE Communications Society Conference on Sensor and Ad Hoc Communications and Networks (SECON 2005) |
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2005-09-24 |
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Santa Clara, California, USA |
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#<DocumentCategory:0x007f418ed84010> |
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| 2005 |
8 |
2 |
RagoDOCS: An Autonomous Dynamically Operated Charging System for Small Mobile Robots |
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Summer @ CENS Research Review |
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2005-08-26 |
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Center for Embedded Networked Se |
University of California, Los Angeles (UCLA) |
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#<DocumentCategory:0x007f418efbef60> |
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| 2005 |
9 |
1 |
Coordinating Camera Motion for Sensing Uncertainty Reduction |
We are interested in improving the sensing fidelity achieved using a given set of sensing resources, by aligning the network configuration precisely to the sensing requirements in the deployment environment. To this end, we develop methods to learn the occlusions to sensing and then develop methods which help a network of mobile cameras to overcome the occlusions. Our method also allows the sensors to adapt to the learnt event distribution. |
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http://www.ee.ucla.edu/~kansal/papers/kansal_sensys05.pdf |
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ACM Sensys |
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307 |
307 |
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2005-11-27 |
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San Diego, CA |
ACM |
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#<DocumentCategory:0x007f418efb5de8> |
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| 2005 |
10 |
1 |
An Investigation of Sensor Integrity |
High Integrity in Sensor Networks studies the effect of compromised data on sensor network data analysis and data fusion algorithms. We are at the start of a study to better understand the compromised data itself so that we can model it in such a way to characterize this affect on analysis. The accelerated life experiment we describe here was instrumented to see how the accuracy of a temperature and humidity sensor changes across mote and sensor systems and across time as the battery dies. We found that the error in the measurements was stable over time, but the bias in the measurements varied greatly across the motes. The experiment gave us more information on the important variables to include in calibration function, so that we can estimate the true measured value from the reported value of the sensor. |
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http://nesl.ee.ucla.edu/fw/integrity/calib_investigation_poster.pdf |
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CENS Annual Research Review |
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2005-10-28 |
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#<DocumentCategory:0x007f418ef90de0> |
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| 2006 |
3 |
1 |
Software Based Memory Protection in Sensor Nodes |
Typical sensor nodes are resource constrained microcontrollers containing user level applications, operating system components, and device drivers in a single address space, with no form of memory protection. A programming error in an application can easily corrupt the state of the operating system and other software components on the node. In this paper, we propose a memory protection scheme that prevents the corruption of operating system state by buggy applications.We use sandboxing to restrict application memory accesses within the address space. Severe resource constraints on the sensor node present interesting challenges in designing a sandbox for user applications.We have implemented and tested our scheme on the SOS operating system. Our experiments were able to detect a memory corruption bug in an application module that had been in use for several months. |
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http://www.ee.ucla.edu/~ram/content/papers/sfi-emnets-06.pdf |
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Third Workshop on Embedded Networked Sensors (EmNets 2006) |
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2006-05-06 |
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#<DocumentCategory:0x007f418ef43ce8> |
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| 2005 |
10 |
2 |
A New Light Sensing Module for Mica Motes |
We present the Illumimote, a new light sensing module for the Mica mote platform. The Illumimote achieves performance comparable to a commercial light intensity meter, while conforming to the size and energy constraints imposed by its application in wireless sensor networks. The Illumimote was developed to replace the Mica sensor board (MTS310) whose slow response time and narrow dynamic range in light intensity capture is unsuitable to many applications, including media production. The Illumimote features significantly improved SNR due to its adoption of high-end photo sensors, amplification and conversion circuits coupled with active noise suppression, application-tuned filter networks, and a noise-attentive manual layout. Unlike the MTS310, the Illumimote can capture RGB color intensity (for color temperature calculation) and incident light angle (which discerns the angle of ray arrival from the strongest source). Our prototype demonstrated significantly faster response time (> 6x) and a much wider dynamic range (> 10x) in light intensity measurement as compared with the MTS310. The light-angle estimation results were well correlated with an average error of just 2.63 degree. |
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http://nesl.ee.ucla.edu/fw/documents/posters/2005/Illumimote_CENSARR2005_HeeminPark.pdf |
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CENS ARR 2005 |
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2005-10-31 |
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| 2005 |
10 |
3 |
Hierarchy of Reconfiguration in Sensor Network Software Systems |
In-situ reconfiguration is indispensable in sensor network deployments. It is required for efficient management and upgrade of software in large scale sensor networks, re-tasking a deployed network or for recovering a deployed system from crippling bugs or malicious intent. A spectrum of techniques for re-programming have been proposed. The major approaches are: <BR>
1. Full binary upgrade supported by TinyOS/Deluge mechansim that allows arbitrary changes to the functionality but incurs a high transmission and storage cost. <BR>
2. The SOS operating system for sensor nodes that consists of a static kernel that is extensible through modular extensions and can be installed and updated over the air. <BR>
3. Application specific virtual machines (ASVMs),which are domain specific interpreters built on top of TinyOS and enable limited high-level changes to the functionality by injecting concise application level scripts. <BR>
<BR>
The three approaches vary in the cost and the flexibility of the updates that they can support. The nature of the update determines the most suitable technique. We have built a system that supports this complete hierarchy of reconfiguration. |
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http://research.cens.ucla.edu/pls/portal/url/item/042418A40B1521B8E0406180528D4C0E |
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Center for Embedded Networked Sensing (CENS) 2005 Annual Research Review |
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2005-10-03 |
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CENS 2005 Annual Research Review |
Center for Embedded Networked Sensing (CENS) |
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| 2005 |
4 |
8 |
Lab-Scale Actuated Sensing Testbeds |
Actuation in sensor networks, in the form of the ability change position and orientation of sensor nodes or their components, has emerged as a critical element in coping with deployment uncertainties and run-time dynamics, and in improving performance and efficiency. To facilitate research on algorithms that manage and exploit actuation and applications that benefit from it, CENS has developed a variety of sensor node platforms with novel actuation capabilities. These platform range from those designed for field deployment such as the NIMS node and the Pacbot data mule) to those designed for lab-scale low-cost experimentation using hardware-in-loop emulation. In this poster we describe three of the lab-scale actuation-capable sensor node platforms that have been developed at the Center. |
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http://research.cens.ucla.edu/pls/portal/url/item/F97868B89A436693E0306180528D30C8 |
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Center for Embedded Networked Sensing (CENS) 2005 NSF site visit |
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2005-04-03 |
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CENS 2005 NSF site visit |
Center for Embedded Networked Sensing (CENS) |
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| 2005 |
11 |
1 |
Dynamically Configurable Robotic Sensor Networks |
In-situ reconfiguration is indispensable in sensor network deployments. It is required for efficient software management in large-scale sensor networks, re-tasking a deployed network, or for recovery after attack. We have built a system that supports multiple levels of reconfiguration. It consists of Dynamic Application Specific Virtual Machine (DASVM) running on the SOS operating system. This is demonstrated on Ragobot, which is a power efficient and scriptable platform for swarm robotic sensors.
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http://nesl.ee.ucla.edu/fw/documents/demos/2006/dvm_ragobot_sensys_05.pdf |
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The 2nd international conference on Embedded Networked Sensor Systems (SenSys 2005) |
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2005-11-03 |
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San Diego |
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| 2005 |
11 |
2 |
A New Light Sensing Module for Mica Motes |
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http://nesl.ee.ucla.edu/fw/documents/slides/2005/Illumimote_Sensors2005_HeeminPark.pdf |
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2005-11-09 |
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| 2005 |
6 |
7 |
Networked Infomechanical Systems (NIMS): Next Generation Sensor Networks for Environmental Monitoring |
Embedded networked sensing systems have been
successfully applied to environmental monitoring in a wide range
of applications. These first results have demonstrated a potential
for advancing fundamental environmental science methods and
environmental management capability as well as for providing
future methods for safeguarding public health. While substantial
progress in sensor network performance has appeared, new
challenges have also emerged. Specifically, the inevitable and
unpredictable time evolution of environmental phenomena
introduces sensing uncertainty and degrades the performance of
event detection, environment characterization, and sensor fusion.
Many of the physical obstacles encountered by static sensors may
be circumvented by a new method, Networked Infomechanical
Systems (NIMS). NIMS integrates distributed, embedded sensing
and computing systems with infrastructure-supported mobility to
enable direct uncertainty characterization, autonomous
adjustment of spatiotemporal sampling rate, and active sensor
fusion. NIMS actuation is also being applied to advancing sensor
network performance through methods based on control of
distributed, directional antenna systems. In addition to advances
in fundamental research objectives, this presentation will
describe the architecture, implementation, and application of
NIMS now deployed and continuously operating in the field. |
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http://nesl.ee.ucla.edu/fw/kansal/nims_mtts05.pdf |
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IEEE MTT-S International Microwave Symposium Digest |
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2005-06-29 |
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| 2010 |
3 |
3 |
Spectrum Signaling for Cognitive Underwater Acoustic Channel Allocation |
The underwater environment varies significantly from traditional electromagnetics. Many cognitive radio techniques that have proven effective in the terrestrial setting cannot simply be transplanted underwater. Furthermore the limited bandwidth and lack of FCC regulations additionally changes the approaches that can be taken. In this paper, we introduce spectrum signaling, an approach for distributed channel allocation for the underwater acoustic environment.
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2010/torres_10_cwcn.pdf |
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Proceedings of IEEE INFOCOM 2010 Workshop on Cognitive Wireless Communications and Networking |
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2010-03-01 |
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| 2005 |
11 |
3 |
A Remote Medical Monitoring and Interaction System |
In this paper, we present the implementation of
a remote monitoring and interaction system for medical
applications. Recent advances in medical platforms have
focused mainly on continuous and constant remote monitoring
of a patient. Compared to existing solutions, our system has
placed emphasis on remote interaction between a patient and a
physician. We provide in this system capabilities to perform
diagnosis and treatment over-the-air. Such system is valuable
for instant response to emergency health alerts. Today, this
emergency process of monitoring and feedback actuation is
done by a self-contained device (such as an implantable
cardioverter-defibrillator), which provides treatment
automatically when detecting abnormalities. We believe that it
is very important to involve the physician in this process of
actuated treatment.
We accomplish this goal by virtually connecting a patient
and a physician anytime anywhere. We propose a mixed twoand
three- tier infrastructure that extends current three-tier
architecture with a GSM/GPRS peer-to-peer channel. We
present a working system that is built on top of commercial
cellular phones and wireless sensor nodes. In our system, a
physician can create and subscribe to ”interests” provided by a
body sensor network deployed on a patient. An interest is
defined as the useful information acquired from applying a
series of computations to collected vital signals. Profiles of
interests can be periodically delivered in the form of health
status reports, or they can be used to trigger emergency health
alerts immediately when abnormalities are detected. The
advanced interactive capabilities of our system allow a remote
physician to further query for detailed information, to create
and subscribe to new interests, to set sensor parameters, and to
trigger actuators for over-the-air treatment. Additionally, we
introduce a concept of multi-resolution to help a physician
identify useful information from a huge amount of sensor data
collected by the body sensor network on a patient and hence to
reduce communication costs. This paper describes why our
proposed infrastructure suits novel medical scenarios and
outlines the design and implementation of our system. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/nesldoc/papers/nesl/2006/djea_mobisys2006_submission.pdf |
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2005-11-30 |
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| 2005 |
11 |
4 |
RAGOBOT: A New Hardware Platform for Research in Wireless Mobile Networks |
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http://www.ee.ucla.edu/~mbs/ipsn05/demo/17_JFriedman.pdf |
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IPSN |
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2005-04-30 |
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Los Angeles, CA |
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| 2005 |
11 |
5 |
Solar Energy Harvesting Wireless Embedded Systems |
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http://www.ee.ucla.edu/~mbs/ipsn05/demo/18_JHsu.pdf |
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IPSN |
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2005-04-30 |
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| 2005 |
11 |
6 |
Heliomote: Enabling Long-Lived Sensor Networks Through Solar Energy Harvesting |
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http://www.ee.ucla.edu/~kansal/papers/sensys_hsu_05.pdf |
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ACM Sensys |
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2005-11-30 |
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San Diego, CA |
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| 2005 |
8 |
3 |
Heliomote: Enabling self-sustained wireless sensor networks through solar energy harvesting |
This paper presents the design, implementation, and performance evaluation of Heliomote, an efficient solar energy harvesting module for
wireless sensor nodes. The key tradeoffs and design decisions impacting power consumption are described. Experimental results, obtained through
measurements and actual sensor network deployments, demonstrate that Heliomote autonomously manages energy harvesting and storage, and
enables self-sustained, harvesting aware sensor network operation. |
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http://www.ee.ucla.edu/~kansal/papers/islped05.pdf |
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ACM-IEEE International Symposium on Low Power Electronic Design (ISLPED) |
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2005-08-30 |
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San Diego, CA |
Student Design Contest Winner |
true |
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#<DocumentCategory:0x007f418ee937a8> |
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| 2006 |
9 |
1 |
Adaptive Duty Cycling for Energy Harvesting Systems |
Harvesting energy from the environment is feasible in many applications to ameliorate the energy limitations in sensor networks. In this paper, we present an adaptive duty cycling algorithm that allows energy harvesting sensor nodes to autonomously adjust their duty cycle according to the energy availability in the environment. The algorithm has three objectives, namely (a) achieving energy neutral operation, i.e., energy consumption should not be more than the energy provided by the environment, (c) maximizing the system performance based on an application utility model subject to the above energy-neutrality constraint, and (c) adapting to the dynamics of the energy source at run-time. We present a model that enables harvesting sensor nodes to predict future energy opportunities based on historical data. We also derive an upper bound on the maximum achievable performance assuming perfect knowledge about the future behavior of the energy source. Our methods are evaluated using data gathered from a prototype solar energy harvesting platform and we show that our algorithm can utilize up to 58% more environmental energy compared to the case when harvesting-aware power management is not used. |
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ISLPED 2006 |
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2006-10-06 |
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Tegernsee, German |
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#<DocumentCategory:0x007f418ee8a950> |
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| 2005 |
4 |
9 |
Remote Storage for Sensor Networks |
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http://www.ee.ucla.edu/~rahulb/reports/RemoteStorage.pdf |
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2005-04-07 |
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| 2006 |
1 |
2 |
Illumimote: A High Performance Light Sensor Module for Wireless Sensor Networks |
We describe application requirements, design, integration and performance evaluation of the Illumimote, a light sensing module for wireless sensor networks. Achieving performance comparable to commercial light meters while conforming to the beneficial size and energy constraints of sensor networks, the Illumimote includes light intensity, RGB color, incident light angle, attitude and temperature sensors. Its maximum power consumption is about 90mW. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2006/Illumimote_DACSDC2006_HeeminPark.pdf |
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2nd place in the 43rd DAC/ISSCC Student Design Contest |
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2006-07-17 |
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San Francisco |
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#<DocumentCategory:0x007f418ee2b310> |
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| 2005 |
11 |
8 |
Fully Quantified Evaluation of Myotatic Stretch Reflex |
The severity and degree of recovery for a traumatic brain injury can be assessed by the myotatic stretch reflex. Descending supraspinal input provides inhibitory modulation of the myotatic stretch reflex. A hyperactive reflex response is correlated with spasticity, which also can be correlated with the degree of damage to the supraspinal input, in essence assessing the severity of traumatic brain injury. The myotatic stretch reflex is clinically evaluated by the Ashworth scale (1 to 5). A rating of 1 is nominal and 5 representing the greatest level of tightness. The Ashworth scale however lacks temporal data and also may vary in terms of interpretation. The solution is a fully quantified evaluation system of the myotatic stretch reflex. A piezoelectric hammer with a predetermined force input, based on original potential energy will quantify the input. MEMS accelerometer and wearable computers can assist us with quantifying the output. Our proposed wearable computer architecture is a platform for health monitoring, based on wireless sensor networks. This architecture is a network enabled system that supports various wearable sensors and contains on-board general computing capabilities for executing individually tailored event detection, alerts, and network communication with various medical informatics services. The MEMS accelerometers are attached to a set anchor point near the ankle. The reflex response can be temporally averaged by integrating acceleration from initial time to final time. The quantified data collected from MEMS accelerometers is transmitted a portable computer (i.e. a Pocket PC). The myotatic stretch reflex can subsequently be normalized by the ratio of averaged acceleration of ipsilesional to contralateral limb. Results indicate that the spastic ipsilesional limb produces a higher acceleration relative to contralateral limb. |
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http://www.ee.ucla.edu/~dcjea/papers/SFN05_myotatic_abstract.pdf |
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http://www.ee.ucla.edu/~dcjea/papers/2005_neuro_myotatic.ppt |
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Neuroscience '05, Symposium of Neuroscience |
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2005-11-25 |
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Washington DC |
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#<DocumentCategory:0x007f418fcce138> |
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| 2006 |
1 |
3 |
Reconfiguration Methods for Mobile Sensor Networks |
Motion may be used in sensor networks to change the network configuration for improving the sensing performance. We consider the problem of controlling motion in a distributed manner for a mobile sensor network for a specific form of motion capability. Mobility itself may have a high resource overhead, hence we exploit a constrained form of mobility which has very low overheads but provides significant reconfiguration potential. We present an architecture which allows each node in the network to learn the medium and phenomenon characteristics. We describe a quantitative metric for sensing performance which is concretely tied to real sensor and medium characteristics, rather than assuming an abstract range based model. The problem of determining
the desirable network configuration is expressed as an optimization of this metric. We present a distributed optimization algorithm which computes a desirable network configuration, and adapts it to environmental changes. The relationship of the proposed algorithm to simulated annealing
and incremental sub-gradient descent based methods is discussed. A key property of our algorithm is that convergence to a desirable configuration can be proved even though no global coordination is involved. A network protocol to implement this algorithm is discussed, followed by simulations and experiments on a laboratory test-bed. |
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http://www.ee.ucla.edu/~kansal/papers/kansal_actuation.pdf |
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2006-01-08 |
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| 2006 |
3 |
2 |
Power Management in Energy Harvesting Sensor Networks |
Power management is an important concern in sensor networks, because a tethered energy infras-
tructure is not available and an obvious concern is to use the available battery energy e±ciently.
However, in some of the sensor networking applications, an additional facility is available to ame-
liorate the energy problem: harvesting energy from the environment. Certain considerations in
using an energy harvesting source are fundamentally di®erent from that in using a battery be-
cause, rather than a limit on the maximum energy, it has a limit on the maximum rate at which
the energy can be used. Further, the harvested energy availability typically varies with time in
a non-deterministic manner. While a deterministic metric such as residual battery su±ces to
characterize the energy availability in the case of batteries, a more sophisticated characterization
may be required for a harvesting source. Another issue that becomes important in networked
systems with multiple harvesting nodes is that di®erent nodes may have di®erent harvesting op-
portunity. In a distributed application, the same end-user performance may be achieved using
di®erent workload allocations, and resultant energy consumptions, at multiple nodes and in this
case it is important to align the workload allocation with the energy availability at the harvesting
nodes. We consider the above issues in power management for energy harvesting sensor networks.
We develop abstractions to characterize the complex time varying nature of such sources with analytically tractable models and use them to address key design issues. We also develop distributed
methods to e±ciently use harvested energy and test these both in simulation and experimentally
on an energy harvesting sensor network, prototyped for this work. |
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http://www.ee.ucla.edu/%7Ekansal/papers/journal_harvesting.pdf |
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2006-03-08 |
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| 2006 |
4 |
1 |
Designing Wireless Sensor Networks as a Shared Resource for Sustainable Development |
Wireless sensor networks (WSNs) are a relatively new and rapidly
developing technology; they have a wide range of applications including
environmental monitoring, agriculture, and public health. Shared
technology is a common usage model for technology adoption in developing
countries. WSNs have great potential to be utilized as a shared resource
due to their on-board processing and ad-hoc networking capabilities,
however their deployment as a shared resource requires that the technical
community first address several challenges. The main challenges include
enabling sensor portability - the frequent movement of sensors within and
between deployments, and rapidly deployable systems - systems that are
quick and simple to deploy. We first discuss the feasibility of using
sensor networks as a shared resource, and then describe our research in
addressing the various technical challenges that arise in enabling such
sensor portability and rapid deployment. We also outline our experiences
in developing and deploying water quality monitoring wireless sensor
networks in Bangladesh and California. |
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http://nesl.ee.ucla.edu/fw/international/ict4d.pdf |
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International Conference on Information and Communication Technologies and Development |
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10 |
2006-05-02 |
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Berkeley, CA |
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#<DocumentCategory:0x007f418fcab048> |
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| 2006 |
4 |
2 |
Adaptive Duty Cycling for Energy Harvesting Systems |
Harvesting energy from the environment is feasible in many applications to ameliorate the energy limitations in sensor networks. In this paper, we present an adaptive duty cycling algorithm which allows energy harvesting sensor nodes to autonomously adjust their duty cycle according to the energy availability in the environment. The algorithm has three objectives: (1) Achieving energy neutral operation, i.e. energy consumption should not be more than the energy provided by the environment, (2) maximizing the system performance based on an application utility model subject to the above constraint, and (3) being adaptive to dynamics of energy source in real-time. For practical application, we discuss a prediction model that enables harvesting sensor nodes to predict future energy opportunities based on historical data. We also derive a theoretically optimal bound on the maximum performance achievable assuming perfect knowledge about the future. Our methods are then evaluated on a prototype solar energy harvesting platform, Heliomote, and we show that our algorithm can utilize up to 58% of the energy which would be wasted if no harvesting aware power management is used |
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http://www.ee.ucla.edu/~jasonh/paper/adc_tech_report.pdf |
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2006-04-30 |
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| 2005 |
1 |
5 |
NeTS-NOSS: Algorithms & System Support for Data Integrity in Wireless Sensor Networks |
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http://nesl.ee.ucla.edu/fw/integrity/noss-cal-all-20050121.pdf |
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2005-01-03 |
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#<DocumentCategory:0x007f418fc9d0d8> |
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| 2006 |
5 |
1 |
Power Management in Energy Harvesting Sensor Networks |
Power management is an important concern in sensor networks, because a tethered energy infrastructure is not
available and an obvious concern is to use the available battery energy efficiently. However, in some of the sensor
networking applications, an additional facility is available to ameliorate the energy problem: harvesting energy
from the environment. Certain considerations in using an energy harvesting source are fundamentally different
from that in using a battery because, rather than a limit on the maximum energy, it has a limit on the maximum
rate at which the energy can be used. Further, the harvested energy availability typically varies with time in a nondeterministic
manner. While a deterministic metric such as residual battery suffices to characterize the energy
availability in the case of batteries, a more sophisticated characterization may be required for a harvesting source.
Another issue that becomes important in networked systems with multiple harvesting nodes is that different nodes
may have different harvesting opportunity. In a distributed application, the same end-user performance may be
achieved using different workload allocations, and resultant energy consumptions, at multiple nodes. In this
case it is important to align the workload allocation with the energy availability at the harvesting nodes. We
consider the above issues in power management for energy harvesting sensor networks. We develop abstractions
to characterize the complex time varying nature of such sources with analytically tractable models and use them
to address key design issues. We also develop distributed methods to efficiently use harvested energy and test
these both in simulation and experimentally on an energy harvesting sensor network, prototyped for this work. |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_tecs.pdf |
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ACM Transactions on Embedded Computing Systems (in revision) |
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35 |
2006-05-11 |
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#<DocumentCategory:0x007f418fc8bf40> |
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| 2006 |
5 |
2 |
Harvesting Aware Power Management for Sensor Networks |
Energy harvesting offers a promising alternative to solve the
sustainability limitations arising from battery size constraints in
sensor networks. Several considerations in using an environmental
energy source are fundamentally different from using
batteries. Rather than a limit on the total energy, harvesting
transducers impose a limit on the instantaneous power
available. Further, environmental energy availability is often
highly variable and a deterministic metric such as residual battery
capacity is not available to characterize the energy source. The
different nodes in a sensor network may also have different energy
harvesting opportunities. Since the same end-user performance may be
achieved using different workload allocations at multiple nodes, it
is important to adapt the workload allocation to the spatio-temporal
energy availability profile in order to enable energy-neutral
operation of the network. This paper describes power management
techniques for such energy harvesting sensor networks. Platform
design considerations as well as power scaling techniques at the
node-level and network-level are described. |
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http://nesl.ee.ucla.edu/fw/kansal/kansal_dac06.pdf |
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43rd Design Automation Conference (DAC) |
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2006-07-11 |
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San Francisco, CA, USA |
ACM |
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#<DocumentCategory:0x007f418fc82df0> |
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| 2005 |
1 |
6 |
Sensor Networking with SOS |
The ability to create robust and energy efficient applications is a primary concern in the sensor network domain. Many current operating systems solve this problem through the creation of static application images that ease verification and optimization, but hinder flexibility and reuse.The SOS operating system breaks away from this model by using established systems techniques to push application development into reusable modules that can be dynamically loaded and modified in a deployed sensor network, with little impact on safety or energy efficiency.In this talk I introduce the architecture of SOS and how it enables the use of dynamic modules in sensor networks. Through a comparison of SOS to both a traditional static sensor network operating system and a virtual machine solution for sensor networks, I argue that SOS occupies a valuable middle ground between energy efficiency and flexibility. |
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http://nesl.ee.ucla.edu/fw/documents/slides/2005/sos_cens_w_05.pdf |
http://nesl.ee.ucla.edu/fw/documents/slides/2005/sos_cens_w_05.ppt |
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CENS Lecture Series |
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0 |
2005-01-13 |
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University of California, Los An |
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#<DocumentCategory:0x007f418fc75c18> |
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| 2004 |
10 |
6 |
Reconfigurable Sensor Networks with SOS |
We present SOS, an operating system that enables reconfiguration of wireless sensor networks. Software on the nodes often needs to be updated post-deployment to support feature upgrades, bug fixes or redefined objectives. It is infeasible to physically reprogram each individual node due to the sheer size of the network and the often inhospitable deployment terrain. The SOS architecture enables remote insertion of binary modules into a running kernel without interrupting the system operation. The SOS core is a non-preemptive, event driven microkernel that can operate on platforms with only 4 KB of SRAM. By using a message passing mechanism and dynamic memory, function and memory references are resolved at run time enabling dynamically loadable binary modules. Native execution of the loadable modules results in superior performance over virtual machines. A complex data gathering application has been successfully tested on SOS showing the suitability of this new operating system for the wireless sensor network domain. |
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http://nesl.ee.ucla.edu/fw/documents/posters/2004/sos04eearr_poster.pdf |
http://nesl.ee.ucla.edu/fw/documents/posters/2004/sos04eearr_poster.ppt |
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UCLA Electrical Engineering Department Annual Research Review (ARR) for 2004 |
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0 |
2004-10-13 |
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University of California, Los An |
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#<DocumentCategory:0x007f418fc60ae8> |
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| 2006 |
4 |
3 |
Making Live a Little Easier or... Compile Time Checking of Run Time Resource Management |
To aid in the efficient and clean design of applications, many sensor network
systems expose interfaces to system developers that allow for the dynamic
creation and manipulation of sensor node resources. But these interfaces are
accompanied by the risk that programming mistakes will lead to mismanaged
resources.
In this talk I will introduce a simple model that characterizes resource usage
in many sensor network applications and how this model can be used to create a
tool to help automate software verification. I will then describe my
experiences in applying such a tool to the code base for the SOS operating
system. And perhaps, along the way, we will come to better understand the
mystic "Property Number Three"... |
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http://nesl.ee.ucla.edu/fw/documents/slides/2006/sheaChecker06cens.pdf |
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CENS Lecture Series |
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0 |
2006-04-13 |
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University of California, Los An |
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#<DocumentCategory:0x007f418fbd3a58> |
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| 2006 |
5 |
3 |
Compile Time Checking of Runtime Resource Management |
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http://nesl.ee.ucla.edu/fw/documents/posters/2006/sheaStaticCheck06arr.pdf |
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UCLA School of Engineering Annual Research Review (ARR) for 2006 |
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0 |
2006-05-13 |
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University of California, Los An |
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#<DocumentCategory:0x007f418fbc6998> |
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| 2005 |
4 |
10 |
SOS - A dynamic operating system for sensor networks |
We present SOS, a new operating system for mote-class sensor nodes that supports run-time reconfiguration of the embedded software. The architecture of SOS consists of dynamically-loaded modules and a statically compiled kernel (ref. figure 1). An application in SOS is composed of one or more modules interacting via asynchronous messages or function calls. Modules are position independent binaries that implement a specific task or function. They operate on their own state which is dynamically allocated at run-time. Examples of modules are routing protocols, sensor drivers and application programs etc |
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http://nesl.ee.ucla.edu/fw/documents/conference/2005/sos05SpotsDemo.pdf |
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The Fourth International Conference on Information Processing in Sensor Networks |
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0 |
2005-04-13 |
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UCLA, Los Angeles, California |
ACM |
true |
false |
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#<DocumentCategory:0x007f418fbbda50> |
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| 2007 |
6 |
4 |
Actuation-Assisted External Calibration of Distributed Sensor Networks |
While cameras have the potential to enable many applications in sensor networks, to be effective they first must be externally calibrated. In prior systems, cameras, identified by controllable light sources, utilized angular measurements amongst themselves to determine their relative positions and orientations. However, the typical camera’s narrow field of view makes such systems susceptible to failures in the presence of occlusions or non-ideal configurations. Actuation-assistance helps to overcome such issues by essentially broadening each camera’s view. In this paper we discuss and implement a prototype system that uses actuation to aid in the external calibration of camera networks. We evaluate our system using simulations and a testbed of MicaZ nodes, equipped with Cyclops camera modules mounted on custom pan-tilt platforms. Our results show that actuation-assistance can dramatically reduce node density requirements for localization convergence.
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http://nesl.ee.ucla.edu/fw/documents/thesis/2007/jeff_mascia_thesis.pdf |
http://nesl.ee.ucla.edu/fw/documents/thesis/2007/jeff_mascia_thesis.tgz |
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M.S. Thesis |
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68 |
2007-06-04 |
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Los Angeles |
UCLA Electrical Engineering Department |
true |
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#<DocumentCategory:0x007f418fbb0940> |
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| 2005 |
10 |
4 |
Handling memory corruption faults in sensor networks |
Typical sensor nodes use resource constrained micro-controllers where user level applications, operating
system components, device drivers, etc., reside within a single address space with no form of memory
protection. A programming error in an application can easily corrupt the state of the operating system
and other software components on the node. To protect against such errors, we propose a two tier software
scheme that achieves: (i) coarse grained memory protection of the operating system state, and (ii)
fine grained detection of memory corruption and subsequent recovery of application components. Coarse
grained memory protection is provided by creating and enforcing an application fault domain that restricts
the memory accesses made by an application to a portion of the address space. The operating
system state is stored outside the application fault domain and is therefore protected from memory corruption.
Fine grained memory corruption detection and recovery is provided within the application fault
domain. Memory corruption faults are detected by a run-time integrity verifier. The associated recovery
mechanism restarts only the affected application module thereby achieving a low recovery time.We have
implemented our scheme in the SOS operating system and tested it on a network of MicaZ nodes. Our
evaluation shows that the scheme effectively handles memory corruption faults while having negligible
impact on the performance and lifetime of real sensor network systems. |
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http://www.ee.ucla.edu/~ram/content/papers/mem-check-nesl-tr.pdf |
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2005 |
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16 |
2005-10-17 |
2005-11-17 |
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#<DocumentCategory:0x007f418f96f848> |
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| 2006 |
2 |
1 |
Embedding Expression: Pervasive Computing Architecture for Art and Entertainment |
Pervasive computing’s historical driver applications include environmental monitoring, safety and security, home and office productivity and guided experience of cultural activities. It also suggests and offers the means to achieve new types of expression in art and entertainment, which has not been a significant area of research despite its cultural and socio-economic importance and unique requirements. This paper discusses motivations and requirements for a pervasive computing architecture for expression, and it presents a specific approach being developed at UCLA in collaboration among research groups in engineering, theater, film and television. |
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Journal of Pervasive and Mobile Computing |
2 |
1 |
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1 |
36 |
36 |
2006-02-06 |
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Elsevier B.V. |
true |
true |
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#<DocumentCategory:0x007f418f95e570> |
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| 2006 |
4 |
4 |
High Fidelity and Multi-Modal Light Sensing Module for Wireless Sensor Networks |
We will show our new light sensing module, the Illumimote, for wireless sensor networks. Our Illumimote is an intelligent, high fidelity and multi-modal wireless light sensing board compatible with the Mica platforms. In the demo, performance of the Illumimote comparable to a commercial light meter and color meter (as used by professional cinematographers) will be demonstrated by measuring incident various light intensities and color temperature settings and
comparing with reference measurements with a commercial light meter and color meter. The Illumimote also has situational sensing capabilities (estimation of incident light angle and board attitude) and they will be shown in the demo. To demonstrate the performance and capabilities of our Illumimote, a couple of lights will be set up in the demo with MicaZ wireless sensor nodes and a laptop base station. Using the light sources, various light and color intensities are generated. The status of the Illumimote is displayed on the GUI visualization interface in real time. |
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http://nesl.ee.ucla.edu/fw/documents/demos/2006/Demo_IPSN2006_HeeminPark.pdf |
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The Fifth International Conference on Information Processing in Sensor Networks (IPSN 2006) |
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0 |
2006-04-08 |
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Nashville, TN |
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#<DocumentCategory:0x007f418f951640> |
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| 2006 |
5 |
4 |
Integrity (I) codes: Message Integrity Protection and Authentication over Insecure Channels |
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http://www2.imm.dtu.dk/~sca/icodes.pdf |
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Proceeding of the IEEE Symposium on Security and Privacy |
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15 |
2006-05-09 |
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false |
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#<DocumentCategory:0x007f418f944788> |
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| 2006 |
6 |
1 |
Fault in Sensor Networks |
This report was a precursor to Chapter 3 in Laura Balzano's masters thesis. Please refer to the thesis for a more complete write-up.
<p>
Faulty data is prevalent in sensor networks, but a careful study of the failure modes and theory to address the impact of the faulty data on data collection, aggregation, and fusion has been neglected. This technical report provides a simple model for data faults, and then looks at simple preliminary analysis of aggregation in the presence of these faults. This is a DRAFT VERSION. |
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http://www.ee.ucla.edu/~sunbeam/publications/fault_generalized.pdf |
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2006-06-30 |
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#<DocumentCategory:0x007f418f937600> |
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| 2006 |
8 |
1 |
Multi-level Software Reconfiguration for Sensor Networks |
In-situ reconfiguration of software is indispensable in embedded networked sensing systems. It is required for re-tasking a deployed network, fixing bugs, introducing new features and tuning the system parameters to the operating environment. We present a system that supports software reconfiguration in embedded sensor networks at multiple levels. The system architecture is based on an operating system consisting of a fixed tiny static kernel and binary modules that can be dynamically inserted, updated or removed unobtrusively. On top of the operating system is a command interpreter, implemented as a dynamically extensible virtual machine, that can execute high-level scripts written in portable byte code. Any binary module dynamically inserted into the operating systems can register custom extensions in the virtual machine interpreter, thus allowing the high-level scripts executed by the virtual machine to efficiently access services exported by a module, such as tuning module parameters. Together these system mechanisms permit the flexibility of selecting the most appropriate level of reconfiguration. In addition to detailing the system architecture and the design choices, the paper presents a systematic analysis of flexibility versus cost tradeoffs provided by these mechanisms. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2006/dvm-emsoft06.pdf |
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ACM Conference on Embedded Systems Software (EMSOFT) |
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10 |
2006-10-02 |
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Seoul |
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true |
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#<DocumentCategory:0x007f418f8e2510> |
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| 2006 |
9 |
2 |
Illumimote: Multi-Modal and High Fidelity Light Sensor Module for Wireless Sensor Networks |
We describe the system requirements, design, system integration and performance evaluation of the Illumimote, a new light sensing module for wireless sensor networks. The Illumimote supports three different light sensing modalities: incident light intensity, color intensites and incident light angle(the angle of ray arrival from the strongest source), and two situational sensing modalities: attitude and temperature. The Illumimote achieves high performance, comparable to commercial light meters, while conforming to the size and energy constraints imposed by its application in wireless sensor networks. We evaluated the performance of our Illumimote for light intensity, color temperature and incident light angle measurements and verified the function of the attitude sensor. The Illumimote consumes about 90mW when all features on board are activated. We describe our design and the experiment design for the performance evaluation |
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http://nesl.ee.ucla.edu/fw/documents/journal/2006/Sensors_Illumimote_HeeminPark.pdf |
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IEEE Sensors Journal |
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0 |
2006-09-19 |
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#<DocumentCategory:0x007f418f8d9438> |
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| 2006 |
9 |
3 |
Software Radio Implementation of Short-range Wireless Standards for Sensor Networking |
Software Defined Radios can provide significant benefits as backend
gateways or base stations for sensor networks, which do not face the
stringent resource constraints of in-network nodes. We extended GNU
Radio with two physical layer implementations of IEEE 802.15.4 and an
FSK modulation, and use the Universal Software Radio Peripheral (USRP)
to interoperate with the Chipcon CC1000 and CC2420 radios found on the
popular Mica2, MicaZ and Telos B motes. The wideband nature of the
USRP makes it feasible for a single SDR base station to simultaneously
communicate on multiple independent channels, and provide network
bridging across incompatible radio standards. The demo will show a
software defined radio base station talking simultaniously to Mica2
and MicaZ nodes and will relay messages coming from the Mica2 to the
MicaZ, and vice versa. Additionally, we will present a unified design
and modeling environment for Software Defined Radio systems, which
aims to bridge the diverse set of design abstractions and software
tools used by engineers specializing in communication, networking, and
embedded systems. Our environment extends Berkeley's Ptolemy II, a
heterogeneous modeling and simulation environment, which provides an
overall framework and graphical interface. We provide a Ptolemy
interface to GNU Radio for physical layer design, and the Click
modular router from MIT, for network level design. This approach
allows designers to work at their preferred design abstraction, while
permitting integrated system modeling, access to rich libraries of
existing system components, and efficient code generation for
implementation on real targets. |
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http://nesl.ee.ucla.edu/fw/thomas/de24-schmid.pdf |
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SenSys 2006 |
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0 |
2006-11-20 |
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Boulder Colorado |
ACM SenSys |
true |
true |
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#<DocumentCategory:0x007f418f8cb388> |
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| 2006 |
9 |
4 |
UrbanCENS: Sensing with the Urban Context in Mind |
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Ubicomp 2006 |
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0 |
2006-09-28 |
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Ubicomp 2006 |
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false |
true |
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#<DocumentCategory:0x007f418f8c1ec8> |
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| 2006 |
10 |
2 |
Illumimote: A High Performance & Multi-Modal Light Sensor Module for Wireless Sensor Networks |
Presentation slides used at the Student Design Contest Award Ceremony, 43rd Design Automation Conference, San Francisco, CA. |
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http://nesl.ee.ucla.edu/fw/documents/slides/2006/DACSDC_2006_Illumimote_HeeminPark.pdf |
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0 |
2006-10-24 |
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San Francisco |
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#<DocumentCategory:0x007f418f8accf8> |
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| 2006 |
11 |
1 |
Harbor: Software-based Memory Protection System for Sensor Nodes |
Many sensor nodes contain resource constrained microcontrollers
where user level applications, operating system components
and device drivers reside within single address space
with no form of memory protection. Programming errors in
one application can easily corrupt the state of the operating
system and other applications on the node. In this paper, we
propose Harbor, a memory protection system that prevents
corruption of state by buggy applications. We use software
based fault isolation (“sandboxing”) to restrict memory accesses
and control flow of applications to protection domains
within the address space. Limited memory on sensor nodes
precludes static partitioning of the address space into different
domains. We have designed Memory map, a flexible and
efficient data structure for recording ownership and layout
information of entire address space. Control flow integrity
is preserved by maintaining a safe stack that stores return
addresses in a protected memory region. Cross domain calls
perform low overhead domain switch within single address
space. Checks are introduced in an application through a
re-write of the compiled binary. The sandboxed binary is
verified on sensor node before it is admitted for execution.
Sensor nodes only need to trust the correctness of the verifier
in the overall system. We have implemented and tested Harbor
on SOS operating system. Our experiments were able to
detect and prevent memory corruption caused due to programming
errors in application modules that have been in
use for several months. Our evaluations show that despite
high overhead, Harbor does not degrade application level
performance of the system under typical workloads. |
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http://www.ee.ucla.edu/~ram/harbor-ipsn06.pdf |
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2006 |
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0 |
2006-11-14 |
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true |
true |
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#<DocumentCategory:0x007f418f80fc50> |
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| 2006 |
12 |
1 |
Design and Implementation of a Wireless Sensor Network for Intelligent Light Control |
We present the design and implementation of the
Illuminator, a sensor network-based intelligent
light control system for entertainment and media
production. Unlike most sensor network applications,
which focus on sensing alone, a distinctive aspect of
Illuminator is that it closes the loop from light sensing to
lighting control. We describe the Illuminator's design
requirements, system architecture, algorithms,
implementation and experimental results. To provide a light sensing module
that meets the high-performance light sensing requirements of
entertainment and media production applications, we developed
the Illumimote, which is a multi-modal and
high fidelity light sensor module well-suited to wireless
sensor networks. The Illuminator system is a toolset to
characterize the illumination profile of a deployed set of
fixed position lights, generate desired lighting effects for
moving targets (actors, scenic elements, etc.) based on user
constraints expressed in a formal language, and assist in
the set up of lights to achieve the same illumination profile
in multiple venues. After characterizing deployed lights,
the Illuminator computes at run-time optimal light settings
to achieve a user-specified actuation profile using an
optimization framework based on a genetic algorithm
Uniquely, it can use deployed sensors to incorporate
changing ambient lighting conditions and moving targets
into actuation. With experimental results, we demonstrate
that the Illuminator handles various high-level user's
constraints and generates optimal light actuation profile.
These results suggest that our system should support
entertainment and media production applications.
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http://nesl.ee.ucla.edu/fw/documents/thesis/2006/dissertation_HeeminPark.pdf |
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UCLA EE Department Ph.D. Dissertation |
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0 |
2006-12-06 |
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true |
true |
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#<DocumentCategory:0x007f418f8068d0> |
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| 2007 |
7 |
1 |
Actuation-Assisted External Calibration of Distributed Camera Sensor Networks |
While cameras have the potential to enable many applications in sensor networks, to be effective they first must be localized. In prior systems, cameras, identified by controllable light sources, utilized angular measurements amongst themselves to determine their relative positions and orientations. However, the typical camera’s narrow field of view makes such systems susceptible to failures in the presence of occlusions or non-ideal configurations. Actuation-assistance helps to overcome such issues by essentially broadening each camera’s view. In this paper we discuss and implement a prototype system that uses actuation to aid in the localization of camera networks. We evaluate our system using simulations and a testbed of MicaZ nodes, equipped with Cyclops camera modules mounted on custom pan-tilt platforms. Our results show that actuation-assistance can dramatically reduce node density requirements for localization convergence. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/actuatedcyclops-infocom.pdf |
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Submitted to Infocom 2008 |
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9 |
2007-07-04 |
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Los Angeles |
UCLA Electrical Engineering Department |
true |
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#<DocumentCategory:0x007f418f7f9540> |
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| 2006 |
12 |
2 |
Design and Implementation of a Wireless Sensor Networks for Intelligent Light Control |
We present the design and implementation of the
Illuminator, a preliminary sensor network-based intelligent
light control system for entertainment and media
production. Unlike most sensor network applications,
which focus on sensing alone, a distinctive aspect of
Illuminator is that it closes the loop from light sensing to
lighting control. We describe the Illuminator's design
requirements, system architecture, algorithms,
implementation and experimental results. To satisfy the
high-performance light sensing requirements of
entertainment and media production applications, the
system uses the Illumimote, which is a multi-modal and
high fidelity light sensor module well-suited to wireless
sensor networks. The Illuminator system is a toolset to
characterize the illumination profile of a deployed set of
fixed position lights, generate desired lighting effects for
moving targets (actors, scenic elements, etc.) based on user
constraints expressed in a formal language, and assist in
the set up of lights to achieve the same illumination profile
in multiple venues. After characterizing deployed lights,
the Illuminator computes at run-time optimal light settings
to achieve a user-specified actuation profile using an
optimization framework based on a genetic algorithm
Uniquely, it can use deployed sensors to incorporate
changing ambient lighting conditions and moving targets
into actuation. With experimental results, we demonstrate
that the Illuminator handles various high-level user's
constraints and generates optimal light actuation profile.
These results suggest that our system should support
entertainment and media production applications.
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http://nesl.ee.ucla.edu/fw/documents/reports/2006/spots07_submitted_HeeminPark.pdf |
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Submitted to SPOTS 2007 |
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0 |
2006-12-07 |
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true |
true |
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#<DocumentCategory:0x007f418f7ebb20> |
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| 2006 |
5 |
5 |
DEVELOPMENT OF MINIATURIZED AND AMBULATORY PRESSURE MONITORING SYSTEM |
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2006 UCLA Engineering Research Review |
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0 |
2006-05-21 |
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UCLA |
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false |
true |
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#<DocumentCategory:0x007f418f7dea10> |
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| 2006 |
12 |
3 |
The Development of an In-vivo Active Pressure Monitoring System |
Abstract—Medical examinations often extract localized
symptoms rather than systemic observations and snap shots
rather than continuous monitoring. Using these methodologies,
one cannot discretely analyze how a patient’s lifestyle
affects his/her physiological conditions and if additional symptoms
occur under various stimuli. We present a minimally
invasive implantable pressure sensing system that actively
monitors long-term physiological changes in real-time. Specifically,
we investigate pressure changes in the upper urinary
tract per degree of obstruction. Our system integrates three
components: a miniaturized sensor module, a lightweight
embedded central processing unit with battery, and a PDA.
Our tether-free system measures pressure continuously for
forty-eight hours and actively transmits an outgoing signal
from an implanted sensor node to a remote PDA twenty feet
away. The software in this in-vivo system is remotely reconfigurable
and can be updated when needed. Preliminary experimental
results of the in-vivo pressure system demonstrate
how it can wirelessly transmit pressure readings measuring 0
to 1 PSI with an accuracy of 0.02 PSI. The challenges in biocompatible
packaging, transducer drift, power management,
and in-vivo signal transmission are discussed. This research
brings researchers a step closer to continuous, real-time systemic
monitoring that will allow one to analyze the dynamic
human physiology. |
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http://cvs.nesl.ucla.edu/cvs/viewcvs.cgi/nesldoc/papers/nesl/2006/Massey_BSN2007.pdf |
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4th International Workshop on Wearable and Implantable Body Sensor Networks |
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0 |
2007-03-21 |
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RWTH Aachen University, Germany |
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true |
true |
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#<DocumentCategory:0x007f418f7d1720> |
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| 2006 |
12 |
4 |
Approximate Data Collection using Resolution Control based on Context |
Approximate data collection is an important
mechanism for real-time and high sampling rate monitoring
applications in body sensor networks, especially when there
are multiple sensor sources. Unlike traditional approaches that
utilize temporal or spatio-temporal correlations among the
measurements of the multiple sensors observing a physical
process to reduce the communication cost, in this paper we
explore the idea of assigning different context-dependent
priorities to the various sensors, and allocating communication
resources according to data from a sensor according to its
priorities. Specifically, a higher number of bits per sample is
allocated to sensors that are of higher priority in the current
context. We demonstrate that the proposed approach provides
accurate inference results while effectively reducing the
communication load. |
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http://www.ee.ucla.edu/~dcjea/papers/bsn2007_djea_finalv4.pdf |
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4th International Workshop on Wearable and Implantable Body Sensor Networks |
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0 |
2007-03-21 |
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RWTH Aachen University, Germany |
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true |
true |
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#<DocumentCategory:0x007f418f7c85f8> |
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| 2006 |
7 |
1 |
Measurement Parameter Estimation with the Ensemble Kalman Filter |
This report was a precursor to Chapter 4 in Laura Balzano's masters thesis.
<p>
The purpose of this project is to explore the method of the Ensemble Kalman
Filter as it could be used in sensor networks. In particular, we
examine how the Ensemble Kalman methods work under faulty data that is
commonly found it sensor networks.
<p>
Sensor networks are envisioned to have large numbers of very small,
very inexpensive devices. We hope to more than offset any detrimental
affect from noisy, faulty data with the high temporal and spatial resolution
brought on my increasingly many devices. In light of these characteristics,
we will need statistical tools to help us leverage the vast amounts of sensor
data without getting tripped up by the low quality of any individual sensor’s
measurements.
The Ensemble Kalman Filter is a point-mass filter which tracks the pdf of the state of a dynamical system by using a Monte Carlo technique.
In this report, we discuss the effectiveness of the Ensemble Kalman Smoother when estimating these parameters on an autoregressive model of decaying soil
moisture. |
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| 2007 |
2 |
1 |
Blind Calibration of Sensor Networks |
THIS IS THE FULL-LENGTH TECH REPORT.
This paper considers the problem of blindly calibrating sensor
response using routine sensor network measurements.
We show that as long as the sensors slightly oversample
the signals of interest, then unknown sensor gains can be
perfectly recovered. Remarkably, neither a controlled stimulus
nor a dense deployment is required. We also characterize
necessary and sucient conditions for the identification
of unknown sensor o sets. Our results exploit incoherence
conditions between the basis for the signals and the canonical
or natural basis for the sensor measurements. Practical
algorithms for gain and o set identification are proposed
based on the singular value decomposition and standard
least squares techniques. We investigate the robustness of
the proposed algorithms to model mismatch and noise on
both simulated data and on data from current sensor network
deployments. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/BalzanoNowakTR.pdf |
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2007-02-20 |
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| 2007 |
12 |
1 |
Energy Consumption Analysis for Bluetooth, WiFi and Cellular Networks. |
This document analyzes power consumption of Bluetooth, WiFi (802.11) and cellular networks for transmitting data produced at f bytes per second. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/PowerAnalysis.pdf |
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2007-12-03 |
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| 2006 |
11 |
2 |
Static Checking for Dynamic Resource Management in Sensor Network Systems |
Many sensor network systems expose general interfaces to system developers for dynamically creating and/or manipulating resources of various kinds. While these interfaces allow programmers to accomplish common system tasks simply and efficiently, they also admit the potential for programmers to mismanage resources, for example through leaked resources or improper resource sharing. These kinds of errors are particularly problematic for sensor networks, given the resource constraints and lack of memory protection on current sensor platforms.
We describe a static analysis technique that brings the safety of static resource management to systems that dynamically manage resources. Our analysis is based on the observation that sensor network applications often manipulate resources in a producer-consumer pattern. In this style, each resource has a unique owner component at any given point in time, who has both the sole capability to manipulate the resource and the responsibility to properly dispose of the resource or transfer ownership to another component. Our analysis enforces this ownership discipline on components at compile time.
We have instantiated our approach as a tool to ensure proper management of dynamically allocated memory in programs written on top of SOS, a sensor network operating system. We have evaluated the tool on all historical versions of all user modules in the SOS CVS repository, as well as on the SOS kernel itself. Our tool generated 25 warnings of which 8 were real errors when checking user modules and 35 warnings of which 2 were real errors when checking the kernel, demonstrating the practical utility of our approach for sensor network systems.
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http://nesl.ee.ucla.edu/fw/documents/reports/2006/shea07static.pdf |
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2006-11-19 |
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UCLA NESL |
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| 2007 |
2 |
2 |
Body Sensor Network in Pervasive Computing Environments for Health Care |
The purpose of this research is to explore how to use body sensor networks with devices in pervasive computing environments to support health care applications. We specifically focus on the two research topics: approximate data collection and context-based user access. Approximate data collection is the process of collecting reduced information from sensors. The technique is applied in the scenario where energy, bandwidth, or storage is the constraint. In pervasive computing environments, various devices embedded in the surroundings are public and shared among multiple users. Such complicated scenario easily results identity confusion problems. Context-based user access describes the rules of the interaction between a user and a device based on their physical states. This ability enables user access to the designate devices and describes the real sage
relationship among these entities. |
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http://www.ee.ucla.edu/~dcjea/researches/ResearchProposal_DavidJea.pdf |
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http://www.ee.ucla.edu/~dcjea/researches/ResearchProposalSlides_DavidJea_v2.pdf |
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PhD Research Proposal |
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2007-02-28 |
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| 2007 |
3 |
1 |
Movement Analysis in Rock-Climbers |
The goal of this demonstration is to present a system de-
veloped to calculate the energy generated in the limbs of a
rock climber. We are interested in showing the difference
between the movements of a beginner, intermediate, and an
advanced climber.
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http://nesl.ee.ucla.edu/fw/thomas/ipsn15d-schmid.pdf |
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http://nesl.ee.ucla.edu/fw/thomas/ipsndemo_v0.2.mov |
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IPSN 2007 |
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2007-04-01 |
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Boston |
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#<DocumentCategory:0x007f418ec2d158> |
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| 2007 |
2 |
3 |
CitySniff & Netcar |
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http://nesl.ee.ucla.edu/fw/thomas/citysniffnetcar.pdf |
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Urbansensing Meeting |
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2007-02-01 |
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UCLA |
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#<DocumentCategory:0x007f418ec20048> |
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| 2007 |
2 |
4 |
Software Radio Implementation of Shortrange Wireless Standards for Sensor Networking |
UCLA EE ARR 2007 presentation |
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http://nesl.ee.ucla.edu/fw/thomas/ee_arr_2007_sdr_presentation.pdf |
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2007-02-01 |
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#<DocumentCategory:0x007f418eae7320> |
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| 2007 |
3 |
2 |
Blind Calibration of Sensor Networks |
This paper considers the problem of blindly calibrating sensor
response using routine sensor network measurements.
We show that as long as the sensors slightly oversample
the signals of interest, then unknown sensor gains can be
perfectly recovered. Remarkably, neither a controlled stimulus
nor a dense deployment is required. We also characterize
necessary and sucient conditions for the identification
of unknown sensor o sets. Our results exploit incoherence
conditions between the basis for the signals and the canonical
or natural basis for the sensor measurements. Practical
algorithms for gain and o set identification are proposed
based on the singular value decomposition and standard
least squares techniques. We investigate the robustness of
the proposed algorithms to model mismatch and noise on
both simulated data and on data from current sensor network
deployments. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2007/ipsn160-balzanonowak.pdf |
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Proceedings of Information Processing in Sensor Networks |
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10 |
2007-04-12 |
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Cambridge, MA |
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true |
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#<DocumentCategory:0x007f418ea92438> |
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| 2007 |
3 |
3 |
Harbor: Software-based Memory Protection for Sensor Nodes |
Many sensor nodes contain resource constrained microcontrollers where user
level applications, operating system components, and device drivers share
a single address space with no form of hardware memory protection. Programming errors in one application can easily corrupt the state of the operating system or other applications. In this paper, we propose Harbor, a memory protection system that prevents many forms of memory corruption. We use software based fault isolation (``sandboxing'') to restrict application memory accesses and control flow to protection domains within the address space. A flexible and efficient memory map data structure records ownership and layout information for memory regions; writes are validated using the memory map. Control flow integrity is preserved by maintaining a safe stack that stores return addresses in a protected memory region. Run-time checks validate computed control flow instructions. Cross domain calls perform low-overhead control transfers between domains. Checks are introduced by rewriting an application's compiled
binary. The sandboxed result is verified on the sensor node before it is admitted for execution. Harbor's fault isolation properties depend only on the
correctness of this verifier and the Harbor runtime. We have implemented and tested Harbor on the SOS operating system. Harbor detected and prevented memory corruption caused by programming errors in application modules that had been in use for several months. Harbor's overhead, though high, is less than that of application-specific virtual machines, and reasonable for typical sensor workloads. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2007/harbor-ipsn07.pdf |
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http://nesl.ee.ucla.edu/fw/documents/posters/2007/harboripsn07poster.ppt |
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In IPSN '07: Proc. 6th International Symposium on Information Processing in Sensor Networks |
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10 |
2007-04-13 |
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Cambridge, MA |
ACM |
true |
true |
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#<DocumentCategory:0x007f418ea690b0> |
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| 2007 |
3 |
4 |
NetCar, an Overview |
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http://nesl.ee.ucla.edu/fw/documents/slides/2007/NetCar.pdf |
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Group meeting |
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2007-03-14 |
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UCLA |
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true |
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#<DocumentCategory:0x007f418ea13e58> |
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| 2008 |
7 |
1 |
NAWMS: Nonintrusive Autonomous Water Monitoring System |
Water is nature's most precious resource and growing demand is pushing fresh water supplies to the brink of non-renewability. New technological and social initiatives that enhance conservation and reduce waste are needed. Providing consumers with fine-grained real-time information has yielded benefits in conservation of power and gasoline. Extending this philosophy to water conservation, we introduce a novel water monitoring system, NAWMS, that similarly empowers users. The goal of our work is to furnish users with an easy-to-use self-calibrating system that provides information on when, where, and how much water they are using. The system uses wireless vibration sensors attached to pipes and, thus, neither plumbing nor special expertise is necessary for its installation. By implementing a non-intrusive, autonomous, and adaptive system using commodity hardware, we believe it is cost-effective and widely deployable. NAWMS makes use of the existing household water flow meter, which is considered accurate, but lacks spatial granularity, and adds vibration sensors on individual water pipes to estimate the water flow to each individual outlet. Compensating for manufacturing, installation, and material variabilities requires calibration of these low cost sensors to achieve a reasonable level of accuracy. We have devised an adaptive auto-calibration procedure, which attempts to solve a two phase linear programming and mixed linear geometric programming problem. We show through experimentation on a three pipe testbed that such a system is indeed feasible and adapts well to minimize error in the water usage estimate. We report an accuracy, over likely domestic flow-rate scenarios, with long-term stability and a mean absolute error of 7%.
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2008/fp1569121580-kim.pdf |
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http://nesl.ee.ucla.edu/~neslfw/documents/slides/2008/Sensys2008_NAWMS.pdf |
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The 6th ACM Conference on Embedded Networked Sensor Systems (SenSys 2008) <b>[Best Paper Award]</b> |
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0 |
2008-11-18 |
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Raleigh, NC |
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true |
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#<DocumentCategory:0x007f418e93ae00> |
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| 2007 |
3 |
5 |
Addressing Fault and Calibration in Wireless Sensor Networks |
Sensors and devices used in wireless sensor networks are state-of-the-art technology
with the lowest possible price. The sensor measurements we get from
these devices are therefore often noisy, incomplete and inaccurate. Researchers
studying wireless sensor networks hypothesize that much more information can
be extracted from hundreds of unreliable measurements spread across a field of
interest than from a smaller number of high-quality, high-reliability instruments
with the same total cost. This thesis offers a basis for exploring that hypothesis
in some detail. We make four contributions. First, we describe sensor faults
commonly seen in recent sensor network deployments, and we formulate statistical
models to assist in the analysis of those faults. Second, we present some
basic tools for assessing the robustness of aggregation algorithms to these common
faults. We then address, in two separate ways, the issue of finding linear
calibration parameters while sensors are deployed. Our third contribution is an
approach to calibration using state space models and non-linear, non-Gaussian
filtering techniques to calibrate sensors without groundtruth knowledge or controlled
stimuli. We evaluate this calibration on simulated sensor data with a
simple dynamical model based on the physical process of soil moisture. Fourth,
we present a general problem formulation for blind calibration which assumes
that the n sensor measurements lie in a subspace of n-dimensional space. We
prove the identifiability of the sensor offsets and gains under this assumption,
and we evaluate implementations on both simulated and real sensor data. |
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http://nesl.ee.ucla.edu/fw/documents/thesis/2007/balzano_msthesis.pdf |
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UCLA EE Department M.S. Thesis |
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99 |
2007-03-18 |
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true |
true |
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#<DocumentCategory:0x007f418e869fa8> |
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| 2006 |
12 |
5 |
ESP Framework: A Middle-ware Architecture for Heterogenous Sensor Networks |
Sensor networks are quickly becoming a flexible, inexpensive, and reliable
platform to provide solutions for a wide variety of applications in real-world
settings. For instance, sensor systems have been used for medical monitoring,
detection and classification for defense purposes, and to perform environmental
monitoring. The increase in the proliferation of sensor networks has paralleled
the use of more heterogeneous systems in deployments.
This thesis presents a framework that enables interoperability between varied
sensor systems and also details some of the fundamental capabilities needed in
such an environment. The ESP framework aims to provide a standard method to
manage, query, and interact with sensor network systems. We provide a method
to describe sensor systems using ESPml, a XML schema, as the modeling language.
The fundamental goal of the schema is to be able to describe sensors
in a simple, compact manner while still having the ability to represent essential
details such as the general setup, the type of data that can be provided, and the
commands that are available. In addition, we present a web services based frameix
work that provides the basic capabilities for locating, managing, and querying
the sensor systems. Finally, challenges such as authentication schemes, logging
services, context integrity, and client interfaces are also explored. |
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http://www.ee.ucla.edu/~sasank/doc/sr_msthesis.pdf |
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UCLA EE Department M.S. Thesis |
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72 |
2006-12-28 |
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true |
true |
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#<DocumentCategory:0x007f418e85cfb0> |
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| 2006 |
12 |
6 |
ESP Framework: A Middleware Architecture For Heterogeneous Sensing Systems |
Sensor systems are quickly becoming a flexible, inexpensive,
and reliable platform to provide solutions for a
wide variety of applications in real-world settings. For
instance, sensor systems have been used for medical
monitoring, detection and classification for defense purposes,
and to perform environmental monitoring. The
increase in the proliferation of sensor systems has paralleled
the use of more heterogeneous systems in deployments.
This paper presents a scalable, open middleware
that enables interoperability between varied sensor systems
and also details some of the fundamental services
needed in such an environment. The ESP framework
aims to provide a standard way to manage, query, and
interact with sensor systems. We provide a method to
describe sensor systems using ESPml, a XML schema,
as the modeling language. The fundamental goal of the
schema is to be able to describe sensor systems in a
simple, compact manner while still having the ability
to represent details such as the general setup, the type
of data that can be provided, and the commands that
are available. In addition, we present a web services
based framework that enables system discovery using
metadata information, interaction using system defined
functional abstractions, and the ability to publish sensor
data for future retrieval and aggregation purposes.
By implementing several systems that scale in terms of
complexity and capabilities, we show that the framework
can accommodate various types of sensor systems. Also,
performance tests of the framework show that the middleware
is able to handle high demands on services. |
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http://www.ee.ucla.edu/~sasank/doc/1569015544.pdf |
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14 |
2006-12-28 |
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#<DocumentCategory:0x007f418e8434e8> |
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| 2007 |
4 |
1 |
A System for Coarse Grained Memory Protection In Tiny Embedded Processors |
Many embedded systems contain resource constrained microcontrollers
where applications, operating system components
and device drivers reside within a single address space
with no form of memory protection. Programming errors in
one application can easily corrupt the state of the operating
system and other applications on the microcontroller.
In this paper we propose a system that provides memory
protection in tiny embedded processors.1. Our system consists
of a software run-time working with minimal low-cost
architectural extensions to the processor core that prevents
corruption of state by buggy applications. We restrict memory
accesses and control flow of applications to protection
domains within the address space. The software run-time
consists of a Memory map: a flexible and efficient data structure
that records ownership and layout information of the
entire address space. Memory map checks are done for store
instructions by hardware accelerators that significantly improve
the performance of our system. We preserve control
flow integrity by maintaining a Safe stack that stores return
addresses in a protected memory region. Cross domain
function calls are redirected through a software based
jump table. Enhancements to the microcontroller call and
return instructions use the jump table to track the current
active domain. We have implemented our scheme on a
VHDL model of ATMEGA103 microcontroller. Our evaluations
show that embedded applications can enjoy the benefits
of memory protection with minimal impact on performance
and a modest increase in the area of the microcontroller. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2007/safeavr-dac07.pdf |
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DAC'07: Proceedings of the 44th Design Automation Conference |
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6 |
2007-06-02 |
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San Diego, California, USA |
ACM |
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#<DocumentCategory:0x007f418e7a5db0> |
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| 2007 |
3 |
6 |
Reputation-based Framework for High Integrity Sensor Networks |
Sensor network technology promises a vast increase in automatic data collection capabilities
through efficient deployment of tiny sensing devices. The technology will allow users to mea-
sure phenomena of interest at unprecedented spatial and temporal densities. However, as with
almost every data-driven technology, the many benefits come with a significant challenge in data
reliability. If wireless sensor networks are really going to provide data for the scientific community,
citizen-driven activism, or organizations which test that companies are upholding environmental
laws, then an important question arises: How can a user trust the accuracy of information pro-
vided by the sensor network? Data integrity is vulnerable to both node and system failures. In
data collection systems, faults are indicators that sensor nodes are not providing useful informa-
tion. In data fusion systems the consequences are more dire; the final outcome is easily affected
by corrupted sensor measurements, and the problems are no longer visibly obvious.
In this paper, we investigate a generalized and unified approach for providing information about
the data accuracy in sensor networks. Our approach is to allow the sensor nodes to develop a
community of trust. We propose a framework where each sensor node maintains reputation metrics
which both represent past behavior of other nodes and are used as an inherent aspect in predicting
their future behavior. We employ a Bayesian formulation, specifically a beta reputation system,
for the algorithm steps of reputation representation, updates, integration and trust evolution.
This framework is available as a middleware service on motes and has been ported to two sensor
network operating systems, TinyOS and SOS. We evaluate the efficacy of this framework using
multiple contexts: (1) a lab-scale testbed of Mica2 motes, (2) Avrora simulations, and (3) real
data sets collected from sensor network deployments in James Reserve. |
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http://nesl.ee.ucla.edu/fw/documents/journal/2007/rfsn_TOSN.pdf |
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2007-03-04 |
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#<DocumentCategory:0x007f418e7a0e50> |
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| 2008 |
4 |
4 |
SPOTLIGHT: Personal Natural Resource Consumption Profiler |
The impending energy and natural resource crisis forces us to research innovative ways of optimizing our resource consumption. Recent studies have shown that a better understanding of an individual’s energy consumption helps people to lower their energy footprint significantly. We propose SPOTLIGHT, a system that profiles an individual's natural resource consumption pattern in real time using wireless sensor network technology. The current SPOTLIGHT prototype consists of power measurement, activity monitoring and energy resource management subsystems. We explore challenges and issues of each subsystem and discuss lessons we have learnt from the prototype deployment. Additionally, we will provide an outlook of extensions of SPOTLIGHT for water and gas management. |
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http://nesl.ee.ucla.edu/fw/younghun/Splt_emnets08.pdf |
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HotEmNets 2008 |
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2008-06-27 |
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Charlottesville, Virginia, USA |
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#<DocumentCategory:0x007f418e786d98> |
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| 2007 |
3 |
7 |
Software Analysis for Wireless Sensor Networks |
Traditional static analysis often uses modular checking to verify a subsystem in isolation, while still reasoning about the entire system. Sensor networks, with their physical ties to the environment, are reactive in nature. Unfortunately, many benefits of modular analysis are lost in reactive systems. This loss results from state space pollution caused by reactive events that, from the perspective of the analysis, may fire at any time.
My work over the past two years explores a slice of this dilemma. The work resulted in a framework that, when completed within the next two months, will vertically integrate static verification with higher level specifications. This integration allows modular static analysis to proceed with a more limited state space based on assumptions coming from the higher level specification. Load time and run time checks are added to the system to insure that assumptions from the specification are properly followed.
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/shea07prospectus.pdf |
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/shea07prospectus_presentation.pdf |
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2007-03-05 |
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UCLA |
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#<DocumentCategory:0x007f418e7614a8> |
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| 2007 |
3 |
8 |
Work Related to Lighthouse |
Recent work on ownership often describes ownership using flow insensitive or flow sensitive types. At times this boundary is not perfectly clear. Flow insensitive ownership analysis tends to use simpler models that facilitate static checking of the system in question. Flow sensitive ownership analysis sit upon more robust languages with tighter ties between the language and system annotations. Lighthouse occupies a point on the design spectrum just shy of the flow sensitive analysis and uses a minimal set of program annotations. It is important to note that the novel aspects of Lighthouse do not come from new analysis techniques, but from the information that Lighthouse extracts from the systems that it examines.
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/shea07prospectus_related.pdf |
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2007-03-05 |
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UCLA |
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#<DocumentCategory:0x007f418e7501d0> |
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| 2007 |
4 |
2 |
Memory Protection in Resource Constrained Sensor Nodes |
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http://nesl.ee.ucla.edu/fw/documents/thesis/2007/ram-defense.ppt |
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PhD Thesis |
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2007-04-05 |
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#<DocumentCategory:0x007f418e732c20> |
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| 2007 |
4 |
3 |
User Access of Public Shared Devices in Pervasive Computing Environments |
To allow for an efficient usage of a device in pervasive computing environments when a user intends to selectively utilize multiple devices within his/her vicinity, reliable and yet convenient authentication is an important requirement. The problem becomes more complex when the accessed device is shared by the public with many different individuals. This paper first illustrates the issues of establishing sessions to such devices (logging in, maintaining a session, and logging out), and then identifies the common pitfall of access-control contexts. We propose an improved context-aware solution that supports a secure, selective, and identifiable user access of public shared devices with high usability. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2007/hcmdss07_davidjea_v01.pdf |
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http://nesl.ee.ucla.edu/pw/NESL/slides/2007/2007_06_hcmdss_MS_v2.pdf |
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Workshop On High Confidence Medical Devices, Software, and Systems (HCMDSS) |
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2007-06-06 |
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| 2007 |
4 |
4 |
sQualNet: An Accurate and Scalable Evaluation Framework for Sensor Networks |
Although there is growing interest in the use of physical testbeds to evaluate the performance of applications and protocols for sensor platforms, such studies also encounter significant challenges that
include the lack of scalability and repeatability, as well as the inability to represent a diverse set of operational scenarios. On the other hand, simulators can typically address the preceding problems but often lack the high degree of fidelity available to the analysts with physical testbeds. In this paper, we present the design and implementation of sQualNet - an accurate and scalable evaluation framework for sensor networks that effectively addresses the preceding challenges. In particular, sQualNet integrates sensor network operating systems with a very high-fidelity simulation of wireless networks such that sensor network applications and protocols can be executed, without modifications, in a repeatable manner under a diverse set of scalable environments. sQualNet extends beyond the existing suite of simulators and emulators in four key aspects: first it supports emulation of sensor network applications and protocols in an efficient and flexible manner; second, it provides an efficient set
of models of diverse sensing phenomena; third, it provides accurate models of both battery power and clock drift effect which have been shown to have a significant impact on sensor network studies; and finally it provides an efficient kernel that allows it to run experiments that provide substantial scalability in both the spatial and temporal contexts. We demonstrate these advantages, both qualitatively and quantitatively, by means of various case studies including a study that evaluates an experiment with up to 1000 nodes running networking application like Surge faster than real time. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2007/ipsn07-squalnet.pdf |
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Proceedings of the International Conference on Information Processing in Sensor Networks (IPSN) |
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2007-04-13 |
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Cambridge, MA |
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| 2008 |
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Two-Tier Framework for Sensor Fault Characterization in Sensor Networks |
For a sensor network to be reliable and useful, sensor data must sustain high Quality of Information (QoI). While QoI depends on many factors, the most crucial is the integrity of sensor data sources themselves. Sensor data quality may be compromised by causes such as noise, drifts, calibration, and faults. On-line detection and isolation of such misbehaviors are crucial to assure high QoI for the end-user, and efficient management of network resources. We describe a two-tiered system for on-line detection of sensor faults. A local tier running at resource-constrained nodes uses an embedded model of the physical world with a hypothesis-testing detector to identify potential faults and notifies a global tier. In turn, the global tier uses these notifications for consistency checking among sensors and provides more robust estimates for events of interest, and also generats feedback to update the local models. We demonstrate the performance of our system by investigating its impact on the application QoI.
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The Second Annual Conference of the International Technology Alliance (ACITA 2008) |
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2008-09-18 |
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London, UK |
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| 2007 |
5 |
1 |
Static Analysis of Bottom Tier Sensor Networks |
Developing software for the lowest tier of sensor networks is difficult. Directly manipulating low level hardware motivates using languages notorious for providing minimal safety to developers. Nontrivial software logic, ranging from routing protocols to to sensor driver state, are also common in these bottom tier systems. Current sensor network research is exploring the use of traditional static analysis to help minimize these challenges.
Static analysis of sensor network systems is often limited by the reactive nature of these systems. A senor node's physical ties to the environment create a reactive system where one of many different events can fire and any time. Direct application of a static analysis to these reactive systems requires overly conservative analysis to handle the nondeterministic event ordering. This work explores extending standard static analysis with event ordering assumptions built into the system being analyzed.
We present an extended version of the Lighthouse memory checker for the SOS operating system. Lighthouse uses dataflow analysis to look for incorrect use of dynamic memory within a single event handler. Our work uses event ordering specifications provided by system developers to augment this analysis. The refined analysis is able to reason about dynamic memory usage across event firings. We apply the extended Lighthouse memory analysis to both user code and kernel code distributed with the SOS operating system. |
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http://nesl.ee.ucla.edu/fw/documents/posters/2007/shea07censarr.pdf |
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CENS ARR |
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2007-05-07 |
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CENS |
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| 2007 |
5 |
2 |
Context-aware Access to Public Shared Devices |
To allow for an efficient usage of a device in pervasive computing environments, reliable and yet convenient user access is an important requirement. The problem becomes more complex when the accessed device is shared by the public with many different individuals. This paper first illustrates the common pitfalls and issues of establishing sessions to such devices. The paper then proposes a context-aware solution that uses different contexts to capture a usage session. The paper presents a general system design that supports a secure, selective, and identifiable user access of public shared devices with high usability. We have implemented a prototype system to demonstrate the concept.
© ACM, (2007). This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in HealthNet'07 Proceedings.
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http://nesl.ee.ucla.edu/fw/documents/conference/2007/healthnet07_davidjea.pdf |
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HealthNet 2007: the First International Workshop on Systems and Networking Support for Health Care and Assisted Living Environments (See Abtract for Copyright information) |
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2007-06-07 |
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Puerto Rico |
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| 2007 |
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Movement Analysis in Rock-Climbers |
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http://nesl.ee.ucla.edu/fw/thomas/climbipsnposter.pdf |
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IPSN 2007 |
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2007-05-07 |
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Boston |
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| 2007 |
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Actuation-Assisted External Calibration of Distributed Camera Sensor Networks |
While cameras have the potential to enable many applications in sensor networks, to be effective they first must be externally calibrated. In prior systems, cameras, identified by controllable light sources, utilized angular measurements amongst themselves to determine their relative positions and orientations. However, the typical camera’s narrow field of view makes such systems susceptible to failures in the presence of occlusions or non-ideal configurations. Actuation-assistance helps to overcome such issues by essentially broadening each camera’s view. In this paper we discuss and implement a prototype system that uses actuation to aid in the external calibration of camera networks. We evaluate our system using simulations and a testbed of MicaZ nodes, equipped with Cyclops camera modules mounted on custom pan-tilt platforms. Our results show that actuation-assistance can dramatically reduce node density requirements for localization convergence. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/actuatedcyclops-long.pdf |
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Technical Report |
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2007-04-04 |
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Los Angeles |
UCLA Electrical Engineering Department |
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| 2007 |
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2 |
Reliable Transfer of Ownership for Estranged Devices |
Body sensor networks (BSN) sometimes involve a dynamic
and flexible membership of its sensors especially when
monitoring of massive users in a disaster scenario. The
problem of estranged devices requires a transfer of
ownership from one BSN to a different BSN. Based on the
models, a BSN has to adapt different mechanisms to address
possible threats caused by estranged devices. The objective
of our work is to illustrate this problem in detail and
demonstrate how we can exploit dynamic context data
collected in a BSN (worn by a patient) to solve the
estranged-device problem. We propose an experiment to
show how a BSN can infer the ownership of a body sensor
node. |
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http://nesl.ee.ucla.edu/fw/documents/demos/2007/IanYap_HealthNet07_DemoAbstract.pdf |
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HealthNet 2007: the First International Workshop on Systems and Networking Support for Health Care and Assisted Living Environments |
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2007-06-06 |
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Puerto Rico |
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| 2007 |
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3 |
Reliable Transfer of Ownership for Estranged Embedded Devices |
A body sensor network(BSN) is a wearable constellation of sensor nodes that collectively monitors the wearer’s vital signals. The BSN is also a highly mobile system where the embedded devices can be added to and removed from its topology dynamically and frequently. When deploying a BSN for each victim during an emergency relief operation,previously uninitialized sensor nodes placed within the same BSN need to quickly associate with one another. The problem we seek to address here is that of node estrangement. A node should be disassociated from a BSN when certain conditions satisfy and may need to be reassociated with another BSN.
This thesis targets specific aspects of the device estrangement and present a system solution that utilizes dynamic context to address the problem. We first investigate the conditions that satisfy for a device’s estrangement from its current network or system, which leads into the process of disassociation of the former owner of node from an estranged device. If the estranged device needs to join a new BSN, it will have to formally reassociate with the latter. We propose a solution that involves an experiment
which demonstrates two BSNs effectively identifying device estrangement when a sensor node is moved from one’s body to another. Each BSN will recognize a change in the context information it has collected and automatically perform the necessary disassociation or reassociation with the estranged device. We present results based on the evaluation of the system’s efficiency and security.
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http://nesl.ee.ucla.edu/fw/documents/thesis/2007/IanYap_MSThesis.pdf |
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Master's Thesis |
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2007-06-06 |
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| 2007 |
1 |
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ViRe: Virtual Reconfiguration Framework for Embedded Processing in Distributed Image Sensors |
Emergence of new technology in sensor networks, such as low-cost CMOS cameras and others, has introduced more sophisticated sensing modalities such as imaging. Applications involving image processing introduce new challenges to the design of sensor network systems. As the embedded processing becomes more complex, in-situ reconfiguration is seen as the key enabling technology to maintain and manage such systems. Reconfiguration can be used for bug-fixes, introducing new features, and tuning system parameters to the operating environment.
<p>
This paper presents the ViRe framework that provides for in-situ reconfiguration of complex image processing applications. Applications, modeled as data-flow graphs, are composed from a library of pre-defined and reusable elements. An efficient run-time system, called the wiring engine, is installed on the nodes to manage the graph and interaction between its elements. It facilitates communication by transferring data in the form of tokens. After initial deployment, the system permits reconfiguration of the graph by allowing modification to the edges and addition/removal of elements. Hence, it is able to support complex graphs comprising of elements with multiple fan-in and fan-out and feedback, while incurring a low memory and execution overhead.
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/balani_vire07.pdf |
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2007-01-06 |
2007-04-06 |
UCLA |
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| 2008 |
11 |
2 |
Application-Specific Trace Compression for Low Bandwidth Trace Logging |
This poster introduces an application-specific trace log compression mechanism targeted for execution on wireless sensor network nodes. Trace logs capture sequences of significant events executed on a node to provide visibility into the system. The application-specific compression mechanism exploits static program control flow knowledge to automate insertion of trace statements that capture trace data in a concise form. Initial evaluation reveals that these compressed trace logs, when generated, consume just over a fifth of the space required by standard trace logging techniques. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2008/SenSys-p433-shea.pdf |
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http://nesl.ee.ucla.edu/fw/documents/posters/2009/shea08low.pdf |
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Proceedings of the 6th ACM Conference on Embedded Network Sensor Systems (SenSys) |
4 |
3 |
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433 |
434 |
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2008-11-22 |
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Raleigh, NC |
ACM |
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| 2007 |
9 |
1 |
Spotlight: Focusing on Energy Consumption of Individuals |
We present Spotlight, a novel application that monitors electrical energy consumption at the individual level. Obtaining reports of energy consumption at this fine granularity allows identifying new areas for energy saving and acting upon it in real-time. Spotlight views appliances as rendering a service to a user and the energy consumption associated with the appliance as a cost for the service. Each participating appliance is specified a service range, a physical vicinity from the appliance within which the user benefits from the service. Using radio receive strength from user-wearable active RFID tags, an appliance is able to determine the users in its service range. In order to make these measurements, each appliance is instrumented with a power meter and an active RFID tag reader. The current implementation of Spotlight uses a COTS power meter and MicaZ motes as active RFID tags and readers.
Abstract The Spotlight system is deployed and tested in an experimental setup with various appliances and users. We evaluate multiple schemes of accounting energy consumption based on an individual's movement profile and the appliances' power profile. Our preliminary results show how the system could detect wasted energy and we discuss interesting individual behavior that could be interpreted for various energy optimizations.
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/spotlight07percomm.pdf |
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2007-09-11 |
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| 2007 |
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An Experimental Study of Network Performance Impact of Increased Latency in Software Defined Radios |
Software Defined Radios are becoming more and more
prevalent. Especially in the radio amateur community,
Software Defined Radios are a big success. The wireless
industry also has considerable interest in the dynamic
reconfigurability and other advantages of Software Defined
Radios. Our research focuses on the latency of Software
Defined Radios and its impact on throughput in modern
wireless protocols. Software Defined Radio systems often
employ a bus system to transfer the samples from a radio
frontend to the processor which introduces a non-negligible
latency. Additionally, the signal processing calculations on
general-purpose processors introduce additional latencies
that are not found on conventional radios. This work
concentrates on one particular Software Defined Radio
system called GNU Radio, an open source Software
Defined Radio application, and one of its hardware
components, the Universal Software Radio Peripheral
(USRP), and analyzes its receive and transmit latencies. We
will use these measurements to characterize the
performance impact on IEEE 802.15.4 implementation in
GNU Radio. Additionally, we present two Software
Defined Radio implementations of short-range radio
standards, a FSK scheme used in the Chipcon CC1000
radio, and the physical layer of IEEE 802.15.4. We use
these implementations for round trip time measurements
and introduce two sample applications, a physical layer
bridge between the FSK scheme and IEEE 802.15.4, and a
dual channel receiver that receives two radio channels
concurrently. |
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http://nesl.ee.ucla.edu/fw/thomas/wintech401-schmid.pdf |
http://acert.ir.bbn.com/projects/gr-ucla |
http://nesl.ee.ucla.edu/fw/thomas/wintech07.pdf |
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WiNTECH`07 |
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2007-09-09 |
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Montreal, Quebec, Canada |
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| 2007 |
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Reliable Transfer of Ownership for Estranged Embedded Devices |
A body sensor network(BSN) is a wearable constellation of sensor nodes that collectively monitors the wearer’s vital signals. The BSN is also a highly mobile system where the embedded devices can be added to and removed from its topology dynamically and frequently. When deploying a BSN for each victim during an emergency relief operation, previously uninitialized sensor nodes placed within the same BSN need to quickly associate with one another. The problem we seek to address here is that of node estrangement. A node should be disassociated from a BSN when certain conditions satisfy and may need to be reassociated with another BSN.
This thesis targets specific aspects of the device estrangement and present a system solution that utilizes dynamic context to address the problem. We first investigate the conditions that satisfy for a device’s estrangement from its current network or system, which leads into the process of disassociation of the former owner of node from an estranged device. If the estranged device needs to join a new BSN, it will have to formally reassociate with the latter. We propose a solution that involves an experiment which demonstrates two BSNs effectively identifying device estrangement when a sensor node is moved from one’s body to another. Each BSN will recognize a change in the context information it has collected and automatically perform the necessary disassociation or reassociation with the estranged device. We present results based on the evaluation of the system’s efficiency and security.
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http://nesl.ee.ucla.edu/fw/documents/thesis/2007/IanYap_MSThesis.pdf |
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Master Thesis |
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2007-06-11 |
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UCLA Electrical Engineering |
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| 2007 |
10 |
1 |
Writing Programs that Work |
Applying ideas from the programming languages community to work within CENS to more easily create stable systems. |
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http://nesl.ee.ucla.edu/fw/documents/slides/2007/kothari07writing.ppt |
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CENS 2007 ARR |
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2007-10-10 |
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Los Angeles, CA |
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| 2007 |
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Knots: An Efficient Single Stack Preemption Mechanism for Resource Constrained Devices |
The low-end embedded systems space is characterized by two classes of operating systems: run-to-completion (RTC) systems such as TinyOS and preemptive multithreading systems such as Mantis. In RTC systems only a single task may exist on the stack at any time, therefore RTC systems have low memory requirements for the stack space but have poor deadline handling capabilities. Preemptive multithreading systems are better at deadline handling but all tasks in the system require memory for their worst-case execution stack at all times. This results in suboptimal amount of memory allocation for the system. The two types of systems define the two end points of a spectrum characterized by varying degrees of deadline handling capabilities and memory requirements. We have designed and implemented a system that by efficiently performing preemption on a single stack offers the flexibility of operating anywhere on this spectrum. It also offers improved deadline handling capabilities than RTC systems and lower memory requirements than preemptive multithreading systems. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/akhi07knots.pdf |
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2007-10-21 |
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Decentralized Cognitive MAC Based on Exploitation of Spatio-temporal Knowledge |
We propose a decentralized MAC protocol for wireless networks that utilizes multiple frequency channels. This protocol allows users to optimize their local spectrum usage via intelligent channel selection. Channel selection takes place based on the spatio-temporal knowledge of each wireless node. Channel quality metrics that give a reliable metric for optimal channel selection are computed and updated for each of the frequency channels. This protocol requires only one transceiver per node and uses temporal synchronization between nodes to avoid the multi-channel hidden terminal problem. It also enables secondary users to opportunistically utilize the primary frequency channels. We describe the design of this protocol and further analyze its performance using simulation. We have compared the performance of our protocol with other multi channel MACs such as MMAC and DCA. Simulation results show that our scheme improves network throughput significantly. We also simulate our protocol when there are primary users transmitting their packets. The results show that secondary users can opportunistically switch their channels to the primary channels and increase the throughput of network. |
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| 2007 |
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4 |
A framework for QoI-inspired analysis for sensor network deployment planning |
The quality of information (QoI) that sensor networks provide to the applications they support is an important design
goal for their deployment and use. In this paper, we introduce a layered framework for QoI-centered evaluation of
sensor network deployment. The layered framework allows
decomposing the deployment evaluation in three steps: in
put pre-processing, core analysis, and result post-processing.
The layering allows the creation of a rich, modular toolkit
for QoI-centered analysis that can accommodate both existing and new system modeling and analysis techniques. We demonstrate the utility of the framework by comparing the QoI performance of finite-sized sensor networks with general
deployment topology. We also derive some new analysis results for the class of applications considered herein. |
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http://www.ee.ucla.edu/~szahedi/research/QoI/QoI_framework.pdf |
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International Workshop on Performance Control in Wireless Sensor Networks, PWSN |
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2007-10-24 |
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Austin , TX |
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| 2006 |
3 |
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Decentralized Cognitive MAC Based on Exploitation of Spatio-temporal Knowledge |
We propose a decentralized MAC protocol for wireless networks that utilizes multiple frequency channels. This protocol allows users to optimize their local spectrum usage via intelligent channel selection. Channel selection takes place based on the spatio-temporal knowledge of each wireless node. Channel quality metrics that give a reliable metric for optimal channel selection are computed and updated for each of the frequency channels. This protocol requires only one transceiver per node and uses temporal synchronization between nodes to avoid the multi-channel hidden terminal problem. It also enables secondary users to opportunistically utilize the primary frequency channels. We describe the design of this protocol and further analyze its performance using simulation. We have compared the performance of our protocol with other multi channel MACs such as MMAC and DCA. Simulation results show that our scheme improves network throughput significantly. We also simulate our protocol when there are primary users transmitting their packets. The results show that secondary users can opportunistically switch their channels to the primary channels and increase the throughput of network. |
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| 2007 |
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A Framework for Data Quality and Feedback in Participatory Sensing |
The rapid adoption of mobile phones by society over the last decade and
the increasing ability to capture, classifying, and transmit a wide
variety of data (image, audio, and location) have enabled a new sensing
paradigm - where humans carrying mobile devices can act as sensor
systems. Human-in-the-loop sensor systems raise many new challenges in
areas of sensor data quality assessment, mobility and sampling
coordination, and user interaction procedures. To this end, we outline
our initial steps in designing an incentive based reputation system for
assessing data quality, provide an overview of techniques to obtain fine
grained contextual information in mobile situations, and detail feedback
mechanisms to enable more interactive and informative sensor systems. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_sensysposter.pdf |
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ACM Sensys Poster Session |
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2007-11-26 |
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Sydney, Australia |
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| 2007 |
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Reputation-based Framework for High Integrity Sensor Networks |
Sensor network technology promises a vast increase in automatic data collection capabilities through efficient deployment of tiny sensing devices. The technology will allow users to measure phenomena of interest at unprecedented spatial and temporal densities. However, as with almost every data-driven technology, the many benefits come with a significant challenge in data reliability. If wireless sensor networks are really going to provide data for the scientific community, citizen-driven activism, or organizations which test that companies are upholding environmental laws, then an important question arises: How can a user trust the accuracy of information provided by the sensor network? Data integrity is vulnerable to both node and system failures. In data collection systems, faults are indicators that sensor nodes are not providing useful information. In data fusion systems the consequences are more dire; the final outcome is easily affected by corrupted sensor measurements, and the problems are no longer visibly obvious.
In this article, we investigate a generalized and unified approach for providing information about the data accuracy in sensor networks. Our approach is to allow the sensor nodes to develop a community of trust. We propose a framework where each sensor node maintains reputation metrics which both represent past behavior of other nodes and are used as an inherent aspect in predicting their future behavior. We employ a Bayesian formulation, specifically a beta reputation system, for the algorithm steps of reputation representation, updates, integration and trust evolution. This framework is available as a middleware service on motes and has been ported to two sensor network operating systems, TinyOS and SOS. We evaluate the efficacy of this framework using multiple contexts: (1) a lab-scale test bed of Mica2 motes, (2) Avrora simulations, and (3) real data sets collected from sensor network deployments in James Reserve. |
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http://nesl.ee.ucla.edu/fw/documents/journal/2007/rfsn_TOSN.pdf |
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ACM Transactions on Sensor Networks (TOSN) |
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| 2007 |
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2 |
Spotlight : Focus on Energy Consumption of Individuals |
We present Spotlight, a novel application that monitors electrical
energy consumption at the individual level. Obtaining reports of
energy consumption at this fine granularity allows identifying new
areas for energy saving and acting upon it in real-time. Spotlight
views appliances as rendering a service to a user and the energy
consumption associated with the appliance as a cost for the service.
Each participating appliance is specified a service range, a physical
vicinity from the appliance within which the user benefits from the
service. Using radio receive strength from user-wearable active RFID
tags, an appliance is able to determine the users in its service
range. In order to make these measurements, each appliance is
instrumented with a power meter and an active RFID tag reader. The
current implementation of Spotlight uses a COTS power meter and MicaZ
motes as active RFID tags and readers.
The Spotlight system is deployed and tested in an experimental setup
with various appliances and users. We evaluate multiple schemes of
accounting energy consumption based on an individual's movement
profile and the appliances' power profile. Our preliminary results
show how the system could detect wasted energy and we discuss
interesting individual behavior that could be interpreted for various
energy optimizations. |
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http://nesl.ee.ucla.edu/fw/documents/slides/2007/SpltCENS.pdf |
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2007-12-03 |
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| 2008 |
2 |
1 |
Exploiting Manufacturing Variations for Compensating Environment-induced Clock Drift in Time Synchronization |
Time synchronization is an essential service in embedded
wireless networked sensing and control systems. It is used
to enable tasks such as synchronized data sampling and ac-
curate time-of-flight estimation, which can be used to lo-
cate nodes. The deviation in nodes’ knowledge of time
and inter-node resynchronization rate are affected by three
sources of time stamping errors: network wireless communi-
cation delays, platform hardware and software delays, and
environment-dependent frequency drift characteristics of the
clock source. The focus of this work is on the last source of
error, the clock source, which becomes a bottleneck when
either required time accuracy or available energy budget
and bandwidth (and thus feasible resynchronization rate)
are too stringent. Traditionally, this has required the use of
expensive clock sources (such as temperature compensation
using precise sensors and calibration models) that are not
cost-effective in low-end wireless sensor nodes. Since the
frequency of a crystal is a product of manufacturing and
environmental parameters, we describe an approach that
exploits the subtle manufacturing variation between a pair
of inexpensive oscillators placed in close proximity to algo-
rithmically compensate for the drift produced by the en-
vironment. The algorithm effectively uses the oscillators
themselves as a sensor that can detect changes in frequency
caused by a variety of environmental factors. We analyze
the performance of our approach using behavioral models
of crystal oscillators in our algorithm simulation. Then we
apply the algorithm to an actual temperature dataset col-
lected at the James Wildlife Reserve in Riverside County,
California, and test the algorithms on a waveform genera-
tor based testbed. The result of our experiments show that
the technique can effectively improve the frequency stability
of an inexpensive uncompensated crystal 5 times with the
potential for even higher gains in future implementations. |
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http://nesl.ee.ucla.edu/fw/thomas/os_sig_08.pdf |
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http://nesl.ee.ucla.edu/fw/thomas/sigmetrics2008_slides.pdf |
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ACM Sigmetrics 2008 |
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2008-06-01 |
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Annapolis, Maryland |
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| 2008 |
2 |
2 |
XCXO: An Ultra-low Cost Ultra-high Accuracy Clock System for Wireless Sensor Networks in Harsh Remote Outdoor Environments |
As the world ecosystem comes under increasing duress
from the effects of global warming, volatile organic compounds (and other air pollutants), oil spills, pesticides, stronger
coastal storms, and more frequent tornadoes and forest fires,
early warning of and effective response to micro, local, and
regional ecological problems is critical. Capturing this data
is an immense challenge requiring long-term study over very
large areas. Further, such a system must operate virtually
free of infrastructure (power and hardline communications
networks) to reduce the cost and environmental impact of
deploying and maintaining it. Such systems, as envisioned
by the scientific community, consist of a large quantity of
sensors each attached to a small battery operated microprocessor replete with a radio communications transceiver.
Each of these sensor terminals is called a node and the entirety of nodes is termed a Wireless Sensor Network (WSN).
WSN’s are, therefore, emerging as a vital element in humanity’s response to a changing climate. |
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http://nesl.ee.ucla.edu/fw/thomas/dac2008.pdf |
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ISSCC/DAC 2008 (Unpublished Student Design Contest Entry, Award Winner) |
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2008-02-01 |
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San Francisco (ISSCC) and Anahei |
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| 2008 |
2 |
3 |
XCT: Crystal Compensated Timer for Low-cost, Low-drift Clocks |
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http://nesl.ee.ucla.edu/fw/thomas/ISSCC%20Poster.pdf |
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ISSCC 2008 |
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2008-02-01 |
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San Francisco |
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| 2007 |
11 |
3 |
Exploiting Social Networks for Sensor Data Sharing with SenseShare |
Social networks like Facebook and MySpace are on the rise and gain more and more users every day. They link together people and their frinds for messaging, organizing parties and events, or to keep up to date with whome is doing what where. SenseShare is an application that exploits these social networks and structures to provide authentication, privacy, and security while sharing sensor data with other people. |
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http://repositories.cdlib.org/cens/Posters/340/ |
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CENS 5th Annual Research Review |
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2007-11-01 |
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| 2008 |
7 |
6 |
Secure Time Synchronization in Sensor Networks |
Time synchronization is critical in sensor networks at many layers of their design. It enables better duty-cycling of the radio, accurate and secure localization, beamforming, and other collaborative signal processing tasks. These benefits make time-synchronization protocols a prime target of malicious adversaries who want to disrupt the normal operation of a sensor network. In this article, we analyze attacks on existing time synchronization protocols for wireless sensor networks and we propose a secure time synchronization toolbox to counter these attacks. This toolbox includes protocols for secure pairwise and group synchronization of nodes that either lie in the neighborhood of each other or are separated by multiple hops. We provide an in-depth analysis of the security and the energy overhead of the proposed protocols. The efficiency of these protocols has been tested through an experimental study on Mica2 motes. |
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http://nesl.ee.ucla.edu/fw/documents/journal/2008/Ganeriwal08_TISSEC.pdf |
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ACM Transactions on Information and Systems Security |
11 |
4 |
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23 |
35 |
2008-07-25 |
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ACM |
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| 2010 |
8 |
3 |
A Biomimetic Quasi-static Electric Field Physical Channel for Underwater Ocean Networks |
Nature has had millions of years to develop and optimize life in the ocean. Nocturnal oceanic animals and those that live at depth cannot rely upon optical notions of vision to navigate, hunt, or avoid predators. Instead, many rely upon an electroreceptive capability achieved through a dense grid of electric field (Voltage) sensors. In this work, we develop and characterize an artificial system which seeks to mimic this capability. The detection range of our resulting proto- type was ≈ 5cm. The position accuracy in the middle of the transmit axis was ±5cm after calibration. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2010/2010-Wuwnet-JF.pdf |
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The Fifth International Workshop on UnderWater Networks (WUWNet) |
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8 |
2010-09-01 |
2010-10-01 |
Woods Hole, MA USA |
ACM |
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| 2008 |
7 |
7 |
Estimating Clock Uncertainty for Efficient Duty-Cycling in Sensor Networks |
Radio duty cycling has received significant attention in sensor networking literature, particularly in the form of protocols for medium access control and topology management. While many protocols have claimed to achieve significant duty-cycling benefits in theory and simulation, these benefits have often not translated into practice. The dominant factor that prevents the optimal usage of the radio in real deployment settings is time uncertainty between sensor nodes which results in overhead in the form of long packet preambles, guard bands, and excessive control packets for synchronization. This paper
proposes an uncertainty-driven approach to duty-cycling, where a model of long-term clock drift is used to minimize the duty-cycling overhead. First, we use long-term empirical measurements to evaluate and analyze in-depth the interplay between three key parameters that influence long-term synchronization: synchronization rate, history of past synchronization beacons, and the estimation scheme. Second, we use this measurement-based study to design a rate-adaptive, energy-efficient long-term time synchronization algorithm that can adapt to changing clock drift and environmental conditions, while achieving application-specific precision with very high probability. Finally, we integrate our uncertainty-driven time synchronization scheme with the BMAC medium access control protocol, and demonstrate one to two orders of magnitude reduction in transmission energy
consumption with negligible impact on packet loss rate.
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http://nesl.ee.ucla.edu/fw/documents/journal/2008/Ganeriwal08_TNET.pdf |
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IEEE/ACM Transactions on Networking (Accepted) |
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1 |
14 |
14 |
2008-07-25 |
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IEEE/ACM |
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| 2008 |
5 |
1 |
Low-Power High-Accuracy Timing Systems for Efficient Duty Cycling |
Time keeping and synchronization are important services
for networked and embedded systems. High quality timing
information allows embedded network nodes to provide
accurate time-stamping, fast localization, efficient duty cycling
schedules, and other basic but essential functions - all
of which are required for low power operation.
In this paper we present a new type of local clock source
called Crystal Compensated Crystal based Timer (XCXT)
and a number of novel algorithms that effectively utilize it to
achieve low power consumption in wireless sensor networks.
The XCXT has timing accuracies similar to timers based on
temperature compensated crystal oscillators (TCXO) but
has a lower implementation cost and requires less power.
Our initial 8MHz prototype unit, using the simplest algorithm,
achieves an effective frequency stability of ±1.2ppm
and consumes only 1.27mW. On the other hand, commercially
available TCXOs with similar stability can cost over
10 times as much and consume over 20mW.
In addition to the prototype, we will present algorithms
that will improve the XCXT’s power consumption by at least
48%, depending on application and environmental conditions.
We will also show how XCXT’s power efficiency can
be improved even further by employing clocks at different
frequency when different time granularities are required by
an application. |
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http://nesl.ee.ucla.edu/fw/thomas/fp113-schmid.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/islped08_1_1_3_4.pdf |
http://nesl.ee.ucla.edu/fw/zainul/islped08_1_1_3_4.ppt |
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ISLPED 2008 |
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2008-08-02 |
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Bangalore, India |
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| 2008 |
5 |
2 |
Hassle Free Fitness Monitoring |
Fitness monitoring is a fundamental service in pervasive healthcare, but finding a balance between usability and privacy is a hard challenge. To lessen users’ anxieties in privacy concerns, we propose a new way of identification by only utilizing imprecise biometrics and existing informa-tion. Our solution is “hassle free” because it maintains the devices’ original user interface without adding additional sensors and sacrificing user privacy. We demonstrate this idea with a fitness monitoring system for the healthy indi-viduals in a workplace. The system uses collected physio-logical information (weight, blood pressure and heart rate) and context information (computer network activity) to identify a user. Our experiments show that we can achieve a correct user identification of up to 87%. We believe that our solution can serve as an easy addition to the simple interfaces of current technology by enhancing them with smart algorithms.
(This is the author's version of the work. It is posted here by permission of ACM for your personal use. Not for redistribution. The definitive version was published in HealthNet 2008) |
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http://nesl.ee.ucla.edu/fw/documents/conference/2008/HealthNet08_djea.pdf |
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Proceedings of the 2nd International Workshop on Systems and Networking Support for Health Care and Assisted Living Environments |
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2008-06-21 |
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| 2008 |
6 |
1 |
Diagnostic Quality Driven Physiological Data Collection for Personal Healthcare |
We believe that each individual is unique, and that it is necessary for diagnosis purpose to have a distinctive combination of signals and data features that fits the personal health status. It is essential to develop mechanisms for reducing the amount of data that needs to be transferred (to mitigate the troublesome periodically recharging of a device) while maintaining diagnostic accuracy. Thus, the system should not uniformly compress the collected physiological data, but compress data in a personalized fashion that preserves the “important” signal features for each individual such that it is enough to make the diagnosis with a required high confidence level. We present a diagnostic quality driven mechanism for remote ECG monitoring, which enables a notation of priorities encoded into the wave segments. The priority is specified by the diagnosis engine or medical experts and is dynamic and individual dependent. The system pre-processes the collected physiological information according to the assigned priority before delivering to the backend server. We demonstrate that the proposed approach provides accurate inference results while effectively compressing the data. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2008/EMBC08_djea.pdf |
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30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) |
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2008-08-27 |
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| 2008 |
7 |
3 |
A Framework for Quality of Information Analysis for Detection-oriented Sensor Network Deployments |
With their increasing capabilities, research efforts in sensor network have been spreading on a variety of aspects. In this paper, we present a system-oriented, layered approach for evaluating their application-related performance. Focusing on sensor-enabled detection systems, an application planner’s point of view of the system is considered and a hypothesis-testing-based analysis framework for evaluating the quality of information (QoI) supported by a sensor network deployment is explored. The QoI properties of centralized, distributed and hybrid decision topologies are investigated and trade-offs explored at the sensor, cluster, and system-level. In the process, the computationally powerful concept of a QoI equivalent sensor is presented and applied in the aforementioned explorations. Finite size networks are considered and limiting behavior and dominance properties are also investigated. Finally, extensions of the analysis framework to faulty sensor and the impact of calibration are also investigated.
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The Second Annual Conference of the International Technology Alliance (ACITA 2008) [Accepted] |
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8 |
2008-07-18 |
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London, UK |
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| 2008 |
7 |
4 |
Simulation Framework for QoI Characterization of Sensor Networks in the Presence of Faults |
The quality of information delivered by a sensor network depends heavily on the integrity of data produced by the sensor nodes themselves. As such, the ability to model a sensor networking application scenario in the presence of faults that affect sensor data integrity is quite crucial. In this paper we describe a sensor network simulation framework that provides high fidelity modeling of sensor faults, and enables users to study end-to-end quality of information. Our sensor fault simulator is based on the popular, open-source simulator OMNet++ and the associated Castalia package for modeling basic sensor network behaviors. The framework provides the ability to model various elements of a complete application scenario including node deployment, physical process, sensor faults, fault detection, and data fusion. This paper will describe the architecture of the simulation platform, the novel sensor fault model for modeling a variety of fault types and progressive failure behaviors in a parameterized fashion, and the enhancements to Castalia with integrated functionalities for fault detection.
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The Second Annual Conference of the International Technology Alliance (ACITA 2008) |
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2 |
2008-09-18 |
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London, UK |
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#<DocumentCategory:0x007f418e4dad88> |
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| 2008 |
7 |
5 |
On the Impact of Time Synchronization on Quality of Information and Network Performance |
Recent new hardware and technology enable low-power inexpensive distributed sensor networks. To realize certain applications such as real time event detection, target tracking and system monitoring, time synchronization is essential. In the literature, a book of time synchronization techniques have been proposed. In general, the goal of a time synchronization mechanism is to devise a scheme that improves accuracy with lower energy consumption. Yet, there is clearly a trade off between accuracy and energy consumption. It would not be always desirable to deploy the most accurate time synchronization as it might drain the power. The choice of a time synchronization mechanism will depend on application's demand on timing accuracy as well as the energy budget. To estimate application's demand and select a proper time synchronization mechanism, the relationship between application's performance or QoI (Quality of Information) and time synchronization services are yet to be investigated. The paper formalizes the relationship between the performance of applications and time synchronization services based on analytic frameworks using representative applications, namely, event detection and estimation. The analysis shows the impact of timing errors for different event duration, target moving speed, number of sensors, sampling frequencies, etc. The analysis framework can also be used to extract the maximum synchronization errors that each application can sustain to achieve the desired QoI. Moreover, time synchronization plays a key role in energy-saving requirements. For example, accurate time synchronization can improve the efficiency of duty-cycling and thus save energy. In this paper, we will investigate the savings in power and bandwidth by employing different stabilities of clock sources.
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The Second Annual Conference of the International Technology Alliance (ACITA 2008) [Accepted] |
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2008-09-18 |
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London, UK |
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#<DocumentCategory:0x007f418e4cd750> |
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| 2007 |
9 |
2 |
Exploring Tradeoffs in Accuracy, Energy and Latency of Scale Invariant Feature Transform in Wireless Camera Networks |
Advances in DSP technology create important avenues of research for embedded vision. One such avenue is the investigation of tradeoffs amongst system parameters which affect the energy, accuracy, and latency of the overall system. This paper reports work on benchmarking the performance and cost of Scale Invariant Feature Transform (SIFT) for visual classification on a Blackfin DSP processor. Through measurements andmodeling of the camera sensor node, we investigate system performance (classification accuracy, latency, energy consumption) in light of image resolution, arithmetic precision, location of processing (local vs. server-side), and processor speed. A case study on counting eggs during avian nesting season is used to experimentally determine the tradeoffs of different design parameters and discuss implications to other application domains. |
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http://ieeexplore.ieee.org/iel5/4357490/4357491/04357539.pdf?tp=&arnumber=4357539&isnumber=4357491 |
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First ACM/IEEE International Conference on Distributed Smart Cameras (ICDSC-07) |
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2007-09-18 |
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Vienna, Austria |
IEEE |
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| 2008 |
8 |
1 |
A Computational Framework for Quality of Information Analysis for Detection-oriented Sensor Networks |
An application planner’s point of view of sensor-enabled detection systems is considered and a hypothesis-testing-based computational framework for evaluating thequality of information (QoI) supported by a sensor networkdeployment is explored. Through a common, modular analysisframework, that decomposes the computational burden of QoIanalysis, the QoI properties of various decision architecturesare investigated and trade-offs explored at the sensor, cluster,and system-level. Both finite and infinite-sized networks areconsidered and extensions of the analysis framework to faultysensor and the impact of calibration are also investigated. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2008/MILCOM08_szahedi_qoi.pdf |
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Proceedings of MILCOM 2008 |
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7 |
2008-11-25 |
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San DIego, CA |
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| 2006 |
9 |
5 |
Design Environment for Rapid Prototyping of Software Defined Radio |
The design of software defined radios is a challenging task that requires the
expertise of a diverse set of engineers. Communication systems engineers use one set of tools to explore the modulation and signal processing algorithms, while network designers use another set of simulators to assess network performance. Implementing these designs requires embedded software engineers to optimize an implementation for a particular target, while addressing issues relating to real-time performance and hardware-software interfaces. Maintaining disparate design environments among these related domains incurs significant overhead in moving from concept to implementation, and fails to exploit the highly flexible nature of software defined radios. In this thesis, we explore a new design environment for software defined radios that allows designers to quickly explore design alternatives, simulate behavior, and map designs to an efficient target implementation. |
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http://nesl.ee.ucla.edu/fw/SDR/thesis_dreier.pdf |
http://acert.ir.bbn.com/viewvc/ucla-design-env/trunk/ |
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2006-09-21 |
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Los Angeles |
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| 2008 |
8 |
2 |
Tiered Architecture for On-Line Detection, Isolation and Repair of Faults in Wireless Sensor Networks |
Wireless sensor networks fuse data from a multiplicity of sensors of different modalities and spatiotemporal scales to provide information for reconnaissance, surveillance, and situational awareness in many defense applications. For decisions to be based on information returned by sensor networks it is crucial that such information be of sustained high quality. While the Quality of Information (QoI) depends on many factors, perhaps the most crucial is the integrity of the sensor data sources themselves. Even ignoring malicious subversion, sensor data quality may be compromised by non-malicious causes such as noise, drifts, calibration, and faults. On-line detection and isolation of such misbehaviors is crucial not only for assuring QoI delivered to the end-user, but also for efficient operation and management by avoiding wasted energy and bandwidth in carrying poor quality data and enabling timely repair of sensors. We describe a two-tiered system for on-line detection of sensor faults. A local tier running at resource-constrained nodes uses an embedded model of the physical world together with a hypothesis-testing detector to identify potential faults in sensor measurements and notifies a global tier. In turn, the global tier uses these notifications on the one hand during fusion for more robust estimation of physical world events of interest to the user, and on the other hand for consistency checking among notifications from various sensors and generating feedback to update the embedded physical world model at the local nodes. Our system eliminates the undesirable attributes of purely centralized and purely distributed approaches that respectively suffer from high resource consumption from sending all data to a sink, and high false alarms due to lack of global knowledge. We demonstrate the performance of our system on diverse real-life sensor faults by using a modeling framework that permits injection of sensor faults to study their impact on the application QoI. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2008/MILCOM08_szahedi_fdd.pdf |
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Proceedings of MILCOM 2008 |
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2008-11-25 |
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San DIego, CA |
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| 2008 |
8 |
3 |
Information Quality Aware Sensor Network Services (Extended Abstract) |
Wireless sensor networks have proven useful for applications in diverse domains. The challenges of scale and resource constraints posed by these systems have led to development of novel network protocols and services, but their focus has been on traditional metrics of quality of service of network data transport. Rather, sensor networks require combining networking quality of service concerns with metrics of quality and integrity of sensor data sources and performance of sensor fusion algorithms. We describe how network protocols, data integrity management, and sensor fusion algorithms can be design to cooperatively optimize the "Quality of Information" returned by a sensor network. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2008/Asilomar08_szahedi.pdf |
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Proceedings of the 2008 Asilomar Conference on Signals, Systems, and Computers [Invited] |
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2008-10-25 |
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Asilomar, Pacific Grove, CA |
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| 2009 |
8 |
2 |
MobiSense - Mobile Network Services for Coordinated Participatory Sensing |
Cellular and Wi-Fi networks now form a global substrate that provides billions of mobile phone users with consistent, location-aware communication and multimedia data access. On this substrate is emerging a new class of mobile phone applications that use the phones location, image and acoustic sensors, and enable people to choose what to sense and when to share data about themselves and their surroundings. Peoples’ natural movement through and among living, work, and “third” spaces, provides spatial and temporal coverage for these modalities, the character of which is impossible to achieve through embedded instrumentation alone. This paper proposes a network service architecture for participatory sensing, describing challenges in (1) network coordination services enabling applications to efficiently select, incentivize and task mobile users based on measures of coverage, capabilities and interests; (2) attestation mechanisms to enable data consumers to assign trust to the data they access; and (3) participatory privacy regulation mechanisms used by data contributors to control what data they share.
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/ISADS2009.pdf |
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Proceedings of the 9th International Symposium on Autonomous Decentralized Systems (ISADS 2009) |
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6 |
2009-03-17 |
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Athens, Greece |
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| 2009 |
6 |
1 |
LIS is More: Improved Diagnostic Logging in Sensor Networks with Log Instrumentation Specifications |
Detailed diagnostic data is a prerequisite for debugging problems and understanding runtime performance in distributed embedded wireless systems. Severe bandwidth limitations, tight timing constraints, and limited program text space hinder the application of standard diagnostic tools within this domain. Our work introduces the Log Instrumentation Specification (LIS) that drives insertion of low overhead logging calls into a system. The LIS language is easy for developers to directly integrate into their daily work flow and, by acting as an intermediary language, facilitates rapid construction of higher level analysis.
Through microbenchmarks of a complete LIS implementation for the TinyOS operating system, we demonstrate that LIS can comfortably fit onto bottom tier embedded systems. We show how we have used LIS to create a complete monitoring infrastructure for wireless sensor networks that uses features of the LIS language to optimize the size of gathered logs, replicate features of specialized logging infrastructures with minimal effort, and jump start debugging of these systems. Finally, we provide examples of our use of LIS to diagnose specific problems and understand system behavior of a sensor network. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2009/shea09lis.pdf |
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2009-06-01 |
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| 2008 |
8 |
4 |
Angle-of-Arrival Assisted Radio Inteferometry (ARI) Target Localization |
In this work, we propose a new technique that makes use of Angle-of-Arrival (AoA) information in conjunction with local interferometry to improve target location estimation. We call this process Angle-of-arrival-assisted Radio Interferometry (ARI). It has a number of desirable attributes including the ability to reduce the synchronization, network, and hardware requirements when operating as the sole RADAR modality and its ability to augment existing pulsed and CW RADAR algorithms. The proposed approach is described and analyzed. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2008/MILCOM08_jfriedman.pdf |
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Proceedings of MILCOM 2008 |
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7 |
2008-11-25 |
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San Diego, CA |
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| 2008 |
9 |
1 |
Virtual Worlds, Real Tasks |
Educators have started recognizing that video games will play a significant role in the future of learning. Online games are the new playground for children and teenagers, and present unique opportunities for rich online learning environments. However, addiction to online games causes educational and social problems for which teachers, parents, and researchers are seeking solutions. And those who create online games bear some responsibility for participants' well-being. I'd like to suggest channeling negative addiction patterns into positive energy by integrating virtual mixed-reality tasks—which can involve real-world community service—into online games. |
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http://www.elearnmag.org/subpage.cfm?section=opinion&article=104-1 |
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ACM eLearn Magazine |
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0 |
2008-09-12 |
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#<DocumentCategory:0x007f418e246d38> |
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| 2008 |
10 |
2 |
Transportation Mode On Mobile Phones |
As mobile phones advance in functionality and capability, they are increasingly being used as instruments for personal monitoring. Applications are being developed that take advantage of the sensing capabilities of mobile phones - many have accelerometers, location capabilities, imagers, and microphones - to infer contextual information. We focus on one type of context, the transportation mode of an individual, with the goal of creating a convenient (no requirement to place sensors externally or have specific position/orientation settings) classification system that uses a mobile phone
with a GPS receiver and an accelerometer sensor to determine if an individual is stationary, walking, running, biking, or in motorized transport. The target application for this transportation mode inference involves assessing the hazard exposure and environmental impact of an individual’s travel patterns. Our prototype classification system consisting of a decision tree followed by a first-order Hidden Markov Model achieves the application requirement of having accuracy level greater than 90% when testing with our dataset consisting of twenty hours of data collected across six individuals. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_iswc.pdf |
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IEEE International Symposium on Wearable Computers |
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4 |
2008-10-03 |
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Pittsburgh, PA |
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#<DocumentCategory:0x007f418e0ac338> |
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| 2008 |
10 |
3 |
Evaluating Participation and Performance in Participatory Sensing |
Because participatory sensing – targeted campaigns where people harness mobile phones as tools for data
collection – involves large and distributed groups of people, participatory sensing systems benefit from tools to measure and evaluate the contributions of individual participants. This paper develops a set of metrics to help participatory sensing organizers determine individual participants’ fit with any given sensing project, and describes experiments evaluating the resulting reputation system. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_urbansense.pdf |
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International Workshop on Urban, Community, and Social Applications of Networked Sensing Systems (UrbanSense) at Sensys |
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5 |
2008-11-03 |
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| 2010 |
2 |
2 |
Recruitment Framework for Participatory Sensing Data Collections |
Mobile phones have evolved from devices that are just used for voice and text communication to platforms that are able to capture and transmit a range of data types (image, audio, and location). The adoption of these increasingly capable devices by society has enabled a potentially pervasive sensing paradigm - participatory sensing. A coordi- nated participatory sensing system engages individuals carrying mobile phones to explore phenomena of interest using in situ data collection. For participatory sensing to succeed, several technical challenges need to be solved. In this paper, we discuss one particular issue: developing a recruitment framework to enable organizers to identify well-suited participants for data collections based on geographic and temporal availability as well as participation habits. This recruitment system is evaluated through a series of pilot data collections where volunteers explored sustainable processes on a university campus. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_pervasive.pdf |
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International Conference on Pervasive Computing (Pervasive) |
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18 |
2010-05-01 |
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#<DocumentCategory:0x007f418e08dde8> |
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| 2008 |
4 |
5 |
ViRe: Virtual Reconfiguration Framework for Embedded Processing in Distributed Image Sensors |
Image processing applications introduce new challenges to the design of sensor network systems via non-trivial in-network computation. As embedded processing becomes more complex, in-situ reconfiguration is seen as the key enabling technology to maintain and manage such systems. In dynamic event-driven heterogeneous sensor networks, reconfiguration also encompasses autonomous re-partitioning of applications across multiple tiers to provide a low-power responsive system by efficiently coping with variations in run-time resource usage and availability. Hence, we aim to provide an efficient lowpower macro-programming environment that supports multidimensional software reconfiguration of heterogeneous imaging networks.
<br>
Working towards this initiative, we present the ViRe framework for mote-class devices based on data-centric application composition and execution. Applications, modeled as dataflow graphs, are composed from a library of pre-defined and reusable image processing elements. Concise scripts capture the wiring information and are used to install applications in the network, while execution on the nodes is performed via processor native code to minimize overhead. A lean run-time engine tightly monitors application execution to provide an efficient, robust and scalable support for complex reconfigurable embedded image processing. Thus, the system is able to lower application repartitioning overhead and minimize loss of work during software
reconfiguration. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2008/Balani_APRES08.pdf |
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Workshop on Adaptive and Reconfigurable Embedded Systems (APRES), held in conjunction with RTAS |
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4 |
2008-04-22 |
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St. Louis, MO, USA |
ACM |
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true |
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#<DocumentCategory:0x007f418e084b08> |
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| 2008 |
10 |
4 |
Using Mobile Phones to Determine Transportation Modes |
As mobile phones advance in functionality and capability, they are being used for more than just
communication. Increasingly, these devices are being employed as instruments for introspection
into habits and situations of individuals and communities. Many of the applications enabled by this
new use of mobile phones rely on knowing contextual information. The focus of this work is on one
type of context, the transportation mode of an individual, with the goal of creating a convenient
(no specific position and orientation setting or attachment procedure) classification system that
uses a mobile phone with a GPS receiver and an accelerometer sensor. The transportation modes
identified include whether an individual is stationary, walking, running, biking, or in motorized
transport. The overall classification system consists of a decision tree followed by a first-order
discrete Hidden Markov Model and achieves an accuracy level of 93.6% when tested on a dataset
consisting of information from sixteen individuals.
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to appear in ACM Transactions on Sensor Networks |
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26 |
2009-05-01 |
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false |
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#<DocumentCategory:0x007f418cdefc90> |
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| 2009 |
2 |
1 |
Compressive Sensing: A Tool for NESL |
Compressive Sensing is an exciting new field that promises tremendous gains for acquiring signals with some redundancy. This set of slides is the authors' interpretation of the processes behind the mechanisms of compressive sensing. |
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http://nesl.ee.ucla.edu/fw/zainul/20090212_CS_groupmeeting.pdf |
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NESL group meeting |
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20 |
2009-02-13 |
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NESL |
NESL |
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true |
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#<DocumentCategory:0x007f418c8babd0> |
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| 2008 |
10 |
5 |
The True Cost of Accurate Time |
The scientific community has long envisioned vast networks
of sensors each attached to a small battery operated micro-
processor replete with a radio communications transceiver.
For these scientists, each of the sensor terminals is called a
node and the entirety of nodes is termed a Wireless Sensor
Network (WSN). WSN's have proven effective in a plethora
of application domains spanning climate science [2] to mil-
itary operations [10]. In applications where remote long-
term operation, broad geographic coverage, low-cost (e.g.
expendable hardware), and rapid deployment are vital, the
WSN o offers a practical and efficient solution. To achieve
remote distributed sensing and computation the WSN must
achieve synchrony among its component nodes. |
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http://nesl.ee.ucla.edu/fw/thomas/hotpower08_schmid.pdf |
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http://nesl.ee.ucla.edu/fw/thomas/hotpower08_slides.pdf |
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HotPower '08 |
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0 |
2008-12-28 |
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San Diego |
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#<DocumentCategory:0x007f418cc1d318> |
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| 2013 |
3 |
3 |
Mobile Context-Aware Inference Toolbox and Service |
Emerging continuous sensing applications pose new challenges on smartphone’s software design. In this paper, we identified 6 classifiers and 9 sensors that can cover 70% of recent inference models for continuous sensing applications. we will describe the design of Mobile Context-Aware Inference Toolbox and Service. The design has two components: a toolbox that provide programmers with commonly used building blocks so they can develop inference models easily; a centralized service that can achieve CPU time and power saving internally by sharing feature extraction result among classifiers as well as sharing classifier inference result among applications. |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWN1I1c19oVklOLW8/edit?usp=sharing |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWMmJhd2RQdWhnMU0/edit?usp=sharing |
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MS Project Report, UCLA Electrical Engineering Department |
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1 |
10 |
10 |
2013-03-01 |
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Los Angeles, CA |
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true |
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#<DocumentCategory:0x007f418e0639a8> |
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| 2009 |
1 |
1 |
Low Bandwidth Call Trace Logging for Sensor Networks |
Call traces can provide detailed insight into the operation of distributed embedded systems. Developers inspect traces to understand and debug systems using manual and automatic techniques such as data mining. Correlation of traces between nodes provides a network level view of system. These traces are typically gathered by logging a globally unique identifier for each called function. Unfortunately, this naive call trace gathering technique results in excessive consumption of the limited memory, bandwidth, and energy resources available in wireless sensor networks.
This paper proposes three new call trace gathering techniques that are designed specifically for the computing platforms with extreme resource constraints. The first technique uses local name spaces and caller side logging to significantly reduce the bit size of function identifiers. The second technique reconstructs call traces from a log of the runtime control flow decisions made by a program. The third technique performs a novel reduction over a program’s control flow graph to limit logging to control flow nodes effecting runtime call decisions. Our work automates the insertion of logging statements into source code for all the techniques described above.
Our experimental results show promising outlook where two of the techniques reduced the size of the log to less than 15% of traces produced by traditional methods. These savings make the new call trace capturing techniques attractive additions to the toolbox employed by developers and users of wireless sensor networks.
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http://nesl.ee.ucla.edu/fw/documents/reports/2009/shea09low.pdf |
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16 |
2009-01-16 |
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true |
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#<DocumentCategory:0x007f418e05a0d8> |
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| 2008 |
6 |
2 |
SpotLight on Personal Natural Resource Management System |
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http://nesl.ee.ucla.edu/fw/documents/slides/2008/SpotLightProposal.pdf |
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Ph. D. Quals Presentation |
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0 |
2008-06-18 |
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#<DocumentCategory:0x007f418d0b88a0> |
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| 2009 |
2 |
2 |
Multistatic Pulse-Wave Angle-of-Arrival-Assisted Relative Interferometric RADAR |
In this work we propose a Pulse-Wave (PW) extension to the Angle-of-arrival-assisted Radio Interferometry (ARI) technique to dramatically reduce the scan-time and the number of vantage points necessary to obtain high-fidelity target position estimation. Accordingly, we call this enhanced process PW-ARI. PW-ARI is the fusion of data from three domains: time (time-of-flight), phase (relative phase-of-arrival), and angle (direction-of-arrival). It has a number of desirable attributes. Foremost among these are its ability to rapidly image extremely large volumes with high accuracy and dense target clusters, support an infinite number of friendly aircraft while providing stealth operational support, and present a spectrally small footprint to both hostile (evade detection and counter-measures) and friendly (maximize electromagnetic compatibility) systems.
<br><br>
Watch the presentation at RADARCON09 <a href="http://nesl.ee.ucla.edu/fw/documents/conference/2009/RADARCON09-JF-01.wmv"> here (120MB, wmv) </a> or on YouTube:
<br><br>
<center>
<b>PART 1 of 2</b><br>
<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/EJKyW7_3dQ0&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/EJKyW7_3dQ0&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
<br><br>
<b>PART 2 of 2</b><br>
<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/-H4stzvxhuc&hl=en&fs=1"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/-H4stzvxhuc&hl=en&fs=1" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>
</center> |
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http://nesl.ee.ucla.edu/fw/documents/conference/2009/RADARCON09-JF-01.pdf |
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http://nesl.ee.ucla.edu/fw/documents/conference/2009/RADARCON09-JF-Slides.pdf |
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http://nesl.ee.ucla.edu/fw/documents/conference/2009/RADARCON09-JF-01.wmv |
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Proc. of IEEE Radar Conference |
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5 |
2009-05-27 |
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Pasadena, CA |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418e01d7c8> |
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| 2009 |
3 |
1 |
Using Context Annotated Mobility Profiles to Recruit Data Collectors in Participatory Sensing |
Mobile phones and accompanying network layers provide a platform to capture and share location, image, and acoustic data. This substrate enables participatory sensing: coordinated data gathering by individuals and communities to explore the world around them. Realizing such widespread and participatory sensing poses difficult challenges. In this paper, we discuss one particular challenge: creating a recruitment service to enable sensing organizers to select well-suited participants. Our approach concentrates on finding participants based on geographic and temporal coverage, as determined by context-annotated mobility pro files that model transportation mode, location, and time. We outline a three-stage recruitment framework designed to be parsimonious so as to limit risk to participants by reducing the location and context information revealed to the system. Finally, we illustrate the utility of the framework, along with corresponding modeling technique for mobility information, by analyzing data from a pilot mobility study consisting of ten users. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_loca.pdf |
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Proceedings of the 4th International Symposium on Location and Context Awareness (LOCA 2009) <b>[Best Paper Award]</b> |
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18 |
2009-05-10 |
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Tokyo, Japan |
Springer-Verlag |
true |
true |
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#<DocumentCategory:0x007f418e00bf00> |
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| 2009 |
3 |
2 |
On the Interaction of Clocks, Power, and Synchronization in Duty-Cycled Embedded Sensor Nodes |
The efficiency of the time synchronization service in wireless sensor networks is tightly connected to the design of the radio, the quality of the clocking hardware, and the synchronization algorithm employed. While improvements can be made on all levels of the system, over the last few years, most work has focused on the algorithmic level to minimize message exchange and in radio architectures to provide accurate time-stamping mechanisms. Surprisingly, the influences of the underlying clock system and its impact on the overall synchronization accuracy has largely been unstudied.
<p>
In this work, we investigate the impact of the clocking subsystem on the time
synchronization service and address, in particular, the influence of changes
in environmental temperature on clock drift in highly duty-cycled wireless
sensor nodes. We also develop formulas that help the system architect choose the optimal resynchronization period to achieve a given synchronization accuracy. We find that the synchronization accuracy has a two region behavior. In the first region, the synchronization accuracy is limited by quantization error,
while int he second region changes in environmental temperature impact the
achievable accuracy.
<p>
We verify our analytic results in simulation and real hardware experiments.
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http://nesl.ee.ucla.edu/fw/thomas/schmid_tosn2009.pdf |
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Accepted for Publication in ACM Transactions on Sensor Networks |
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0 |
2010-03-01 |
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true |
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#<DocumentCategory:0x007f418e0062f8> |
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| 2009 |
4 |
1 |
Multi-Channel IEEE 802.15.4 Packet Capture Using Software Defined Radio |
Software Defined Radio enables new protocols that are flexible and quick to deploy. Researchers
can use the programmability of Software Radios to create tools that monitor and debug their work.
In this paper, Open-source hardware and software is used to deploy a multi-channel monitoring
tool of the IEEE 802.15.4 protocol. |
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http://nesl.ee.ucla.edu/fw/thomas/leslie_choong_multichannel_ieee802154.pdf |
http://wiki.nesl.ucla.edu/doku.php?id=transitioning_multi-channel_ieee_802.15.4_packet_capture |
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UCLA M.Sc. Thesis Project |
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2009-04-06 |
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true |
true |
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#<DocumentCategory:0x007f418dff4af8> |
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| 2013 |
3 |
4 |
Android Context Service |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWeVBGYWhMR2x1dUk/edit?usp=sharing |
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MS Project Report, UCLA MS Online Program |
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0 |
2013-03-01 |
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Los Angeles, CA |
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true |
true |
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#<DocumentCategory:0x007f418d1f3558> |
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| 2009 |
4 |
2 |
Toward Quality of Information Aware Rate Control for Sensor Networks |
In sensor networks, it is the Quality of Information (QoI) delivered to the end user that is of primary interest. In general, measurements from different sensor nodes do not contribute equally to the QoI because of differing sensing modalities, node locations, noise levels, sensing channel conditions, fault status, and physical process dynamics. In addition, metrics of QoI are highly application dependent, such as probability of detection of an event or fidelity of reconstruction of a spatio-temporal process. Despite these considerations, traditional data dissemination protocols in sensor networks have been designed with a focus on metrics such as throughput, packet delivery ratio, latency, and fair division of bandwidth, and are thus oblivious to the importance and quality of sensor data and the target application. In this paper, we argue for sensor network protocols that are cognizant of and use feedback from the sensor fusion algorithms to explicitly optimize for application-relevant QoI metrics during network resource allocation decisions. Through analysis and simulation we demonstrate the application-level performance benefits accruing from such a QoI-aware approach to network resource management in the context of a centralized sensor rate selection mechanism for an event detection application scenario. |
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http://nesl.ee.ucla.edu/fw/zainul/QoIRC-febid09.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/QoIRC-Febid09-slides.pdf |
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Fourth International Workshop on Feedback Control Implementation and Design in Computing Systems and Networks |
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8 |
2009-04-08 |
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San Francisco |
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true |
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#<DocumentCategory:0x007f418e1b9f00> |
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| 2009 |
5 |
1 |
Weighted l-1 Minimization for Event Detection in Sensor Networks |
Event detection is an important application of wireless sensor networks. When the event signature is sparse in a known domain, mechanisms from the emerging area of Compressed Sensing (CS) can be applied for estimation with average measurement rates far lower than the Nyquist requirement. A recently proposed algorithm called IDEA uses knowledge of where the signal is sparse combined with a greedy search procedure called Orthogonal Matching Pursuit (OMP) to demonstrate that detection can be performed in the sparse domain with even fewer measurements. A different approach called Basis Pursuit (BP), which uses norm minimization, provides better performance in reconstruction but suffers from a larger sampling cost since it tries to estimate the signal completely.
In this paper, we introduce a mechanism that uses a modified BP approach for detection of sparse signals with known signature. The modification is inspired from a novel development that uses an adaptively weighted version of BP. We show, through simulation and experiments on MicaZ motes, that by appropriately weighting the coefficients during norm minimization, detection performance exceeds that of an unweighted approach at comparable sampling rates. |
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http://nesl.ee.ucla.edu/fw/zainul/weightedl1.pdf |
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7 |
2009-05-03 |
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#<DocumentCategory:0x007f418e1aca30> |
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| 2009 |
5 |
2 |
SewerSnort: A Drifting Sensor for In-situ Sewer Gas Monitoring |
Biochemical activities in sewer pipes generate various volatile substances that lead to several serious problems such as malodor complaints and lawsuits, concrete and metal corrosion, increased operational costs, and health risks. Frequent inspections are critical to maintain sewer health, yet are extremely expensive given the extent of the sewer system and the “unfriendliness” of the environment. In this paper we propose SewerSnort, a low cost, unmanned, fully automated in-sewer gas monitoring system. A sensor float is introduced at the upstream station and drifts to the end pumping station, collecting location
tagged gas measurements. The retrieved SewerSnort provides an accurate gas exposure profile to be used for preventive maintenance and/or repair. The key innovations of SewerSnort are the fully automated, end-to-end monitoring solution and the low energy self localizing strategy. From the implementation
standpoint, the key enablers are the float mechanical design that fits the sewer constraints and the embedded sensor design that matches the float form factor and complies with the tight energy constraints. Experiments based on a dry land emulator demonstrate the feasibility of the SewerSnort concept, in particular, the localization technique and the embedded sensor design. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2009/SECON2009-JF-CR.pdf |
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Sixth Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks (SECON 2009) |
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0 |
2009-06-06 |
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Rome, Italy |
IEEE |
true |
true |
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#<DocumentCategory:0x007f418e1a7170> |
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| 2009 |
5 |
3 |
Energy Efficient Sampling for Event Detection in Wireless Sensor Networks |
Compressive Sensing (CS) is a recently developed mechanism that allows signal acquisition and compression to be performed in one inexpensive step so that the sampling process itself produces a compressed version of the signal. This significantly improves systemic energy efficiency because the average sampling rate can be considerably reduced and explicit compression eliminated.
In this paper, we introduce a modification to the canonical CS recovery technique that enables even higher gains for event detection applications. We show a practical implementation of this compressive detection with energy constrained wireless sensor nodes and quantify the gains accrued through simulation and experimentation.
<br>
<hr>
<a href=http://nesl.ee.ucla.edu/fw/zainul/ISLPED-WBPcode.zip>Source Code</a>
<hr> |
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http://nesl.ee.ucla.edu/fw/zainul/sp166-charbiwala.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/islped09-slides.pdf |
http://nesl.ee.ucla.edu/fw/zainul/islped09-slides.key |
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Proceedings of the International Symposium on Low Power Electronics and Design (ISLPED) |
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419 |
424 |
6 |
2009-08-01 |
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San Francisco, CA |
ACM |
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true |
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#<DocumentCategory:0x007f418e1a16d0> |
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| 2009 |
5 |
4 |
Building Principles for a Quality of Information Specification for Sensor Information |
In the highly heterogeneous environments of coalition operations, sharing of sensor-originated information with desired quality characteristics is key to the effective execution of coalition tasks. A characterization of the quality of information (QoI) is useful in many contexts, and can be invaluable in making decisions such as trusting, managing, and using information in particular applications. However, the manner of representing the QoI is highly application-dependent that leads to the divergence in how QoI is characterized and expressed hampering the effective and streamlined execution of coalition tasks. An application-agnostic QoI specification can provide consistency in the representation of information and its quality, and enable QoI-aware determinations across many different applications. In this paper, an application-agnostic QoI model which can be readily customized to the needs of specific applications is presented. Object-oriented modelling principles to attain a QoI model are leveraged that can be used in many different contexts. |
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Proceedings of the 12th International Conference on Information Fusion (Fusion '09) |
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2009-07-10 |
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Seattle, Washington, USA |
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| 2013 |
4 |
1 |
SensorAct: Design and Implementation of Fine-grained Sensing and Control Sharing in Buildings |
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http://nesl.ee.ucla.edu/fw/documents/posters/2013/arjunan-poster-nsdi13.pdf |
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10th Symposium on Networked Systems Design and Implementation |
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2013-04-01 |
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ACM USENIX |
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#<DocumentCategory:0x007f418e186c18> |
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| 2009 |
5 |
5 |
Temperature Compensated Time Synchronization |
Time synchronization in embedded sensor networks is an important service for
correlating data between nodes and communication scheduling. While many
different approaches to the problem are possible, one major effect of clock
frequency difference between nodes, environmental temperature changes, has
often been left out of the solution. The common assumption that the
temperature is static over a certain period of time is often used as an excuse
to assume constant frequency errors in a clock. This assumption
forces synchronization protocols to resynchronize too often. While there
exists hardware solutions to this problem, their prohibitive high cost and
power consumption make them unsuitable for some applications, such as wireless
sensor networks.<br>
Temperature Compensated Time Synchronization (TCTS) exploits the on-board temperature
sensor existing in many sensor network platforms. It uses this
temperature sensor to autonomously calibrate the local oscillator and removes
effects of environmental temperature changes. This allows a time
synchronization protocol to increase its resynchronization period, without
loosing synchronization accuracy, and thus saves energy and communication
overhead. In addition, TCTS provides a stable clock source when
radio communication is impaired. We present the theory behind TCTS,
and provide initial results of a simulated comparison of TCTS and the Flooding
Time Synchronization Protocol.
<p />
The code for TCTS can be found here:<br />
<a href="https://projects.nesl.ucla.edu/view/gitweb.cgi?p=thomas/tinyos-2.x-tcts;a=summary">https://projects.nesl.ucla.edu/view/gitweb.cgi?p=thomas/tinyos-2.x-tcts;a=summary</a> |
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http://nesl.ee.ucla.edu/fw/thomas/schmid_esl2009.pdf |
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IEEE Embedded Systems Letters |
1 |
2 |
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37 |
41 |
5 |
2009-08-01 |
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#<DocumentCategory:0x007f418e181240> |
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| 2009 |
6 |
2 |
Improving Data Integrity with Randomness -- A Compressive Sensing Approach |
Data loss in wireless sensor systems is inevitable, either due to exogenous (such as transmission medium impediments) or endogenous (such as faulty sensors) causes. While there have been many attempts at coping with this issue, recent developments in the area of Compressive Sensing (CS) enable a new perspective. Since many natural signals are compressible, it is possible to employ CS, not only to reduce the effective sampling rate, but to improve the robustness of the system at a given Quality of Information (QoI). This is possible because reconstruction algorithms for compressively sampled signals are not hampered by the stochastic nature of wireless link disturbances and sensor malfunctions, which has traditionally plagued attempts at proactively handling the effects of these errors. In this paper, we show how reconstruction error remains unchanged despite extreme data losses by marginally increasing the average sampling rate. A challenge with this approach is that link errors and sensor faults exhibit bursty exponentially distributed losses, while CS strategies assume independent uniformly distributed random sampling instants. We show that a simple re-ordering of samples prior to communication re-enables successful reconstruction with high probability. |
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http://nesl.ee.ucla.edu/fw/zainul/CSQoI-acita09-paper.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/CSQoI-acita09-poster.pdf |
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Annual Conference of the ITA |
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2 |
2009-09-10 |
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Maryland, USA |
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| 2009 |
6 |
3 |
Optimizing Bandwidth of Call Traces for Wireless Embedded Systems |
Call traces expose runtime behaviors that greatly aid system developers in profiling performance and diagnosing problems within wireless embedded applications. Strict resource constraints limit the volume of trace data that can be handled on embedded devices, especially bandwidth limited wireless embedded systems. We propose two new call trace gathering techniques, local identifier logging and control flow logging, which provide significant reductions in bandwidth consumption compared to the current standard practice of global identifier logging. Intuition into the savings made possible by the proposed trace gathering techniques is provided by an analytical comparison of the bandwidth required by various call tracing approaches. Confirmation of this intuition is demonstrated through experimentation that reveals log bandwidth savings of approximately 85% compared to global identifier logging using flat name spaces, and 35% compared to global identifier logging using optimal Huffman coding. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2009/shea09optimization.pdf |
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IEEE Embedded Systems Letters |
1 |
1 |
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4 |
2009-05-01 |
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IEEE |
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true |
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| 2009 |
5 |
6 |
Electrostatic Transconduction for Underwater Communication and Imaging |
With the emergence of unmanned marine robots and sensors, underwater communication systems have received much attention in recent years. Existing systems for underwater communication largely depend on acoustic technologies. However, acoustic communication is riddled with problems from time-varying multipath propagation to large latencies. Radio systems, however, depend on electromagnetic propagation that is determined by the frequency variation of the permittivity of seawater and, experimentally, results in extremely high attenuation of the signal. In this work, I will present a series of research developments that create a system capable of communication, detection, navigation, and imaging at substantial
bandwidth in highly permeable dielectric media (such as salt water). |
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http://nesl.ee.ucla.edu/fw/documents/reports/2009/2009_05_phdproposal_JF.pdf |
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Ph.D. Thesis Prospectus |
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2009-05-28 |
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Los Angeles |
UCLA |
false |
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| 2009 |
6 |
4 |
On the Interaction of Clocks and Power in Embedded Sensor Nodes |
Sensor networks have matured beyond academic research with industry now
considering the advantages of using wireless sensors. With this growth,
reliability and real-time demands increase, and thus timing becomes more
and more relevant. Further, recent research has shown that current
clock systems become a bottle neck as one pushes the duty-cycles of
embedded systems beyond 0.01%. This work presents the current clock
technologies available on the market, examines the influence of these
clock technologies on power consumption in embedded wireless devices,
and provides guidelines for embedded platform developers who must choose
among the different clock circuits for their own embedded designs.
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http://nesl.ee.ucla.edu/fw/thomas/schmid2009techreport.pdf |
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Techreport |
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2009-06-28 |
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true |
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#<DocumentCategory:0x007f418e16b710> |
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| 2009 |
7 |
1 |
ViridiScope: Design and Implementation of a Fine Grained Power Monitoring System for Homes |
A key prerequisite for residential energy conservation is knowing when
and where energy is being spent. Unfortunately, the current
generation of energy reporting devices only
provide partial and coarse grained information or require
expensive professional installation. This limitation is because of
the presumption that calculating per-appliance consumption
requires per-appliance current measurements.
However, since appliances typically emit measurable signals when
they are consuming energy, we can estimate their consumption using indirect sensors.
This paper presents ViridiScope, a fine-grained power monitoring
system that furnishes users with an economical, easy-to-install,
self-calibrating tool that provides power consumption of virtually
every appliance in the home. ViridiScope uses ambient signals from
inexpensive sensors near appliances to estimate power consumption, thus
no in-line sensor is necessary. We use a model-based
machine learning algorithm that automates the sensor calibration
process. Through experiments in a real house, we show that ViridiScope
can estimate the end-point power consumption to within 10% error. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2009/UbiComp2009-YK.pdf |
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11th international conference on Ubiquitous Computing(UbiComp 2009) |
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0 |
2009-09-05 |
2009-10-05 |
Orlando, Florida |
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| 2009 |
7 |
2 |
Beyond the Medical X-ray, Non-ionizing Electrostatic Transconduction and its Biomedical Applications |
<b>Abstract</b><br>
The use of high-energy X-rays for medical imaging is so well
established that it is known even by the typical pedestrian. However,
X-ray imaging has a number of draw backs including a lack of
functional imaging, an inability to image soft tissue without toxic
contrast materials, and the inherent hazards in exposure to ionizing
radiation. In interventional cardiology, X-ray images merely provide a
rough outline of the heart and clinicians must rely on intuition and
the tactile response of their probes for guidance. In this talk we
present early research on the use of electrostatic transconduction --
the use of near-field longitudinal dielectric waves -- for digital
communication and sensing purposes and discuss its potential in
displacing X-ray imaging in cardiac ablation procedures. This talk
will be jointly presented by Dorothea Hall, MD, of the UCLA Medical
Center and Jonathan Friedman, MSEE, of NESL/CENS.<br><br>
<b>Watch the Seminar</b><br>
<a href="http://nesl.ee.ucla.edu/fw/documents/slides/2009/2009_07_CENS_Talk_BeyondXray_LoRes.wmv">Low-resolution, 50MB, 150kbps WMV</a><br>
<a href="http://nesl.ee.ucla.edu/fw/documents/slides/2009/2009_07_CENS_Talk_BeyondXray_HiRes.wmv">High-resolution, 390MB, 1.1Mbps WMV</a><br>
<br><br>
<b>Jonathan Friedman</b> is a Ph.D. Candidate in Electrical Engineering in
the Networked Embedded Systems Laboratory (NESL) and the Center for
Embedded Networked Sensing (CENS) at the University of California, Los
Angeles (UCLA). Jonathan attended the Georgia Institute of Technology
(Georgia Tech) for his undergraduate education where he received a
B.S. degree in Computer Engineering with an emphasis on embedded and
mixed signal design. His M.S. degree is from UCLA in Electrical
Engineering with a thesis entitled: "IRIS: The Design of a Ultra-low
Power Infrared Communications and Obstacle Avoidance Array for Fleets
of Mobile Sensor Nodes Operating in Dynamic Environments." Jonathan
previously served as the Assistant Director of IT for an IMAX
(large-format movie theaters) subsidiary, has founded three startup
companies, won four design awards, sent over one-hundred product
designs into commercial production, and holds two patents. His current
research interests lie in sensor-systems design for salt-water and
biomedical applications.<br><br>
<b>Dorothea Hall</b>, M.D. is a Clinical Instructor in the Department of
Anesthesiology at the David Geffen School of Medicine at UCLA. She
attended medical school at the Medical College of Wisconsin, Milwaukee
(MCW) where she also did her residency. She recently completed a
fellowship in cardiothoracic anesthesia and is board certified in
transesophageal echocardiography (heart ultrasounds taken though the
esophagus). She authored a case presentation for the 2007 American
Society of Anesthesiology (ASA) General Meeting. Her research
interests include perioperative radiation safety, cardiovascular
anesthesia, and cardiac catheterization procedures. She is currently
responsible for the training of anesthesia residents at the UCLA
Medical Center. |
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http://nesl.ee.ucla.edu/fw/documents/slides/2009/2009_07_CENS_Talk_BeyondXray_LoRes.wmv |
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2009 Center for Embedded Networked Sensing (CENS) Technical Seminar Series |
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2009-07-13 |
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Los Angeles, California |
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| 2010 |
3 |
1 |
Resolving Complex Targets in Multipath Environments Using ARI RADAR Systems |
In this work, we introduce Frequency Modulated Angle-of-arrival-assisted Relative Interferometry (FM-ARI), which leverages the unique talents of ARI systems to provide robust high-resolution 3D imaging of complex targets given the presence of other reflectors (clutter) in the environment. The proposed approach is described and analyzed. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2010/RADARCON10-JF-01.pdf |
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http://nesl.ee.ucla.edu/fw/documents/posters/2010/2010_Radarcon_Poster-jf.pdf |
http://nesl.ee.ucla.edu/fw/documents/posters/2010/2010_Radarcon_Poster-jf.pptx |
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IEEE International Radar Conference (RADARCON) |
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6 |
2010-05-01 |
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Washington DC |
IEEE |
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true |
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#<DocumentCategory:0x007f418d2d1fd8> |
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| 2009 |
7 |
3 |
Log Instrumentation Specifications and Low Overhead Logging |
Severe resource constraints in bottom tier distributed embedded wireless systems hinder attempts to understand runtime behavior of deployed systems. Detailed diagnostic logs can provide the required insight, but must be obtained without violating bandwidth limitations, timing constraints, and other challenges of the target domain. This talk introduces the Log Instrumentation Specification (LIS) language that is used to describe focused logging tasks and drive the instrumentation of source code to collect the requested logs. The LIS language is easy for developers to use directly in their daily work flow and expressive enough to act as an intermediate language targeted by higher level analysis. The runtime logging support needed by LIS fits comfortably on low end sensing devices, allowing LIS to be applied to a wide range of systems. We will examine recent applications of LIS to diagnose problems in sensor networks and observe general runtime behavior. The end of the talk will focus on two new techniques for gathering call traces. The proposed techniques, local identifier logging and control flow logging, significantly reduce the bandwidth required to gather call traces compared to the standard call tracing technique currently used within the embedded sensor network community. |
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http://nesl.ee.ucla.edu/fw/documents/slides/2009/shea09log.pdf |
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CENS Technical Seminar |
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0 |
2009-07-17 |
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UCLA |
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true |
true |
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#<DocumentCategory:0x007f418cdf0348> |
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| 2009 |
8 |
1 |
Software-Defined Underwater Acoustic Networking Platform |
Currently acoustics is the primary modality for underwater communication even though it presents a difficult channel. To try and cope with the challenges of the channel many MAC protocols and PHY layer techniques have been proposed. In this paper we present a research platform that allows developers to easily implement and compare their protocols in an underwater network and configure them at runtime. We have built our platform using widely supported software that has been successfully used in terrestrial radio and network development. The flexibility of development tools such as software defined radio have provided the ability for rapid growth in the community. Our platform adapts some of these tools to work well with the underwater environment while maintaining flexibility, ultimately providing an end-to-end networking approach for underwater acoustic development. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/WUWNET2009-DT.pdf |
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Proceedings of the ACM International Workshop on UnderWater Networks (WUWNET-2009) <b>[Best Paper Award]</b> |
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8 |
2009-11-17 |
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true |
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#<DocumentCategory:0x007f418c92e260> |
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| 2009 |
8 |
3 |
Angle-of-arrival-assisted Relative Interferometric Localization Using Software Defined Radios |
<h2>Abstract</h2>
In this work, we present SDR-ARI – a Software Defined Radio (SDR) approach to an Angle-of-arrival-assisted Relative Interferometric (ARI) RADAR transceiver. It has a number of desirable attributes including the ability to reduce the synchronization, network, and hardware requirements when operating as the sole RADAR modality and its ability to augment existing pulsed and CW RADAR algorithms. While, ARI encoding was initially proposed in prior work, no implementation had been completed and only a pure hardware approach to the receiver was reported. We have developed and implemented a software-defined model in Matlab, and have designed, simulated, and implemented an SDR-ARI transceiver utilizing USRP hardware and gnuRadio software. The use of software-defined radio has allowed us to implement ARI in a timely manner. The proposed approach is described and analyzed.
<h2>Watch the Conference Presentation</h2>
Download the talk via the "Associated AV Files" link below (WMV format, ~150MB)<br>
...or watch it here:<br><br>
<center>
<object width="400" height="300"><param name="allowfullscreen" value="true" /><param name="allowscriptaccess" value="always" /><param name="movie" value="http://vimeo.com/moogaloop.swf?clip_id=7214157&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1" /><embed src="http://vimeo.com/moogaloop.swf?clip_id=7214157&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" width="400" height="300"></embed></object><p><a href="http://vimeo.com/7214157">MILCOM 2009: Angle-of-arrival-assisted Relative Interferometric Localization Using Software-Defined Radio</a> from <a href="http://vimeo.com/user2516931">Jonathan Friedman</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
</center> |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/MILCOM09-JF-01.pdf |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/MILCOM09-JF-01_Slides.pdf |
http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/MILCOM09-JF-01_Slides.pptx |
http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/MILCOM09-JF-01_Talk.wmv |
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Proceedings of MILCOM 2009 |
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8 |
2009-11-17 |
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Boston, MA |
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| 2009 |
9 |
1 |
Demo Abstract: Low-power High-precision Timing Hardware for Sensor Networks |
In this demonstration, we will present three key technolo- gies we recently developed to improve time synchronization accuracy in sensor networks: (1) Temperature Driven Time Synchronization, (2) Low-Power Sub-μSecond Time Syn- chronization, and (3) Low-Power FPGA implementation of a High-Low Timer. |
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http://nesl.ee.ucla.edu/fw/thomas/sensys2009.pdf |
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SenSys |
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2009-11-16 |
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Berkeley |
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#<DocumentCategory:0x007f418cde0da8> |
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| 2009 |
9 |
2 |
Time in Wireless Embedded Systems |
Wireless embedded networks have matured beyond academic research as industry now considers the advantages of using wireless sensors. With this growth, reliability and real-time demands increase, thus timing becomes more and more relevant. In this dissertation, we focus on the development of highly stable, low-power clock systems for wireless embedded systems. Wireless embedded networks, due to their wire-free nature, present one of the most extreme power budget design challenges in the field of electronics. Improvements in timing can reduce the energy required to operate an embedded network. However, the more accurate a time source is, the more power it consumes. To comprehensively address the time and power problems in wireless embedded systems, this dissertation studies the exploitation of dual-crystal clock architectures to combat effects of temperature induced frequency error and high power consumption of high-frequency clocks. Combining these architectures with the inherent communication capabilities of wireless embedded systems, this dissertation proposes two new technologies; (1) a new time synchronization service that automatically calibrates a local clock to changes in temperature; (2) a high-low frequency timer that allows a duty-cycled embedded system to achieve ultra low-power sleep, while keeping fine granularity time resolution offered only by high power, high frequency clocks. |
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http://nesl.ee.ucla.edu/fw/thomas/defense_slides.pdf |
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Ph.D. Dissertation |
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2009-09-16 |
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UCLA |
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| 2010 |
7 |
2 |
SensLoc: Sensing Everyday Places and Paths using Less Energy |
Continuously understanding a user’s location context in colloquial terms and the paths that connect the locations un- locks many opportunities for emerging applications. While extensive research effort has been made on efficiently track- ing a user’s raw coordinates, few attempts have been made to efficiently provide everyday contextual information about these locations as places and paths. We introduce SensLoc, a practical location service to provide such contextual information, abstracting location as place visits and path travels from sensor signals. SensLoc comprises of a robust place detection algorithm, a sensitive movement detector, and an on- demand path tracker. Based on a user’s mobility, SensLoc proactively controls active cycle of a GPS receiver, a Wi- Fi scanner, and an accelerometer. Pilot studies show that SensLoc can correctly detect 94% of the place visits, track 95% of the total travel distance, and still only consume 13% of energy than algorithms that periodically collect coordinates to provide the same information. |
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ACM SenSys |
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2010-11-01 |
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Zurich, Switzerland |
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#<DocumentCategory:0x007f418d6b9268> |
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| 2009 |
7 |
4 |
Compressive Oversampling for Robust Data Transmission in Sensor Networks |
Data loss in wireless sensing applications is inevitable and while there have been many attempts at coping with this issue, recent developments in the area of Compressive Sensing (CS) provide a new and attractive perspective. Since many physical signals of interest are known to be sparse or compressible, employing CS, not only compresses the data and reduces effective transmission rate, but also improves the robustness of the system to channel erasures. This is possible because reconstruction algorithms for compressively sampled signals are not hampered by the stochastic nature of wireless link disturbances, which has traditionally plagued attempts at proactively handling the effects of these errors. In this paper, we propose that if CS is employed for source compression, then CS can further be exploited as an application layer erasure coding strategy for recovering missing data. We show that CS erasure encoding (CSEC) with random sampling is robust for handling missing data in erasure channels, paralleling the performance of BCH codes, with the added benefit of graceful degradation of the reconstruction error even when the amount of missing data far exceeds the designed redundancy. Further, since CSEC is equivalent to nominal oversampling in the incoherent measurement basis, it is computationally cheaper than conventional erasure coding. We support our proposal through extensive performance studies. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2009/200907_infocomsubmission_ZC.pdf |
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Under submission |
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2009-07-24 |
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#<DocumentCategory:0x007f418cc7b2b0> |
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| 2009 |
9 |
3 |
Challenges in Resource Monitoring for Residential Spaces |
Buildings consume approximately 73% of the total electrical energy, and 12%
of the potable water resource in the United States. Even a moderate reduction in this sector results in significant monetary and resource savings. Fine-grained resource monitoring is regarded as one technology that could help
consumers and building owners to understand, and thus reduce, their resource
waste. In this paper, we discuss challenges emerging from these fine grained resource monitoring systems through an empirical study of long-term monitoring data of a residential space. We collected water and electricity usage over 5 months from a single family house. Using a matched filter mechanism we detect several water and electrical events happening in the house, showing that with simple mathematical tools, these data traces reveal already a lot of information about the consumption patterns. We further discuss challenges in fine grained load monitoring using the main power meter, advocating that synchronous water and power traces help to disambiguate several power consumers.
In addition, our analysis revealed interesting privacy implications occurring
while monitoring a household's resource consumption at high time resolution.
We discuss this problem that hampers the successful adaptation of these
technologies. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2009/BUILDSYS09-YK.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2009/BuildSys09YK.pdf |
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BuildSys 2009 in conjunction with ACM SenSys 2009 |
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2009-11-27 |
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#<DocumentCategory:0x007f418c921268> |
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| 2009 |
10 |
1 |
ViridiScope: Design and Implementation of a Fine Grained Power Monitoring System for Homes |
Talk Slides |
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http://nesl.ee.ucla.edu/fw/documents/slides/2009/UbiComp09ViridiScopeYK.pdf |
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2009-10-03 |
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UbiComp2009 |
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| 2009 |
11 |
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Challenges in Resource Monitoring for Residential Spaces |
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http://nesl.ee.ucla.edu/fw/documents/slides/2009/BuildSys09YK.pdf |
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2009-11-04 |
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ACM BuildSys 2009 |
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#<DocumentCategory:0x007f418cca1d98> |
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| 2009 |
12 |
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Compressive Oversampling for Robust Data Transmission in Sensor Networks |
Data loss in wireless sensing applications is inevitable and while there have been many attempts at coping with this issue, recent developments in the area of Compressive Sensing (CS) provide a new and attractive perspective. Since many physical signals of interest are known to be sparse or compressible, employing CS, not only compresses the data and reduces effective transmission rate, but also improves the robustness of the system to channel erasures. This is possible because reconstruction algorithms for compressively sampled signals are not hampered by the stochastic nature of wireless link disturbances, which has traditionally plagued attempts at proactively handling the effects of these errors. In this paper, we propose that if CS is employed for source compression, then CS can further be exploited as an application layer erasure coding strategy for recovering missing data. We show that CS erasure encoding (CSEC) with random sampling is efficient for handling missing data in erasure channels, paralleling the performance of BCH codes, with the added benefit of graceful degradation of the reconstruction error even when the amount of missing data far exceeds the designed redundancy. Further, since CSEC is equivalent to nominal oversampling in the incoherent measurement basis, it is computationally cheaper than conventional erasure coding. We support our proposal through extensive performance studies.
<hr><br>
<b>Errata</b>: In Figs. 9, 10 and 11, the legend for CSEC should be k=80, k=80 and k=75 respectively, instead of k=75, k=75 and k=72.
<hr><br>
<a href=http://nesl.ee.ucla.edu/fw/zainul/Infocom-CSECcode.zip> <b>Code</b> </a> (Warning: >100MB data files included)
<div style="width:425px" id="__ss_9074978"> <strong style="display:block;margin:12px 0 4px"><a href="http://www.slideshare.net/zainulcharbiwala/compressive-oversampling-for-robust-data-transmission-in-sensor-networks-presented-at-infocom-2010" title="Compressive Oversampling for Robust Data Transmission in Sensor Networks - Presented at INFOCOM 2010" target="_blank">Compressive Oversampling for Robust Data Transmission in Sensor Networks - Presented at INFOCOM 2010</a></strong> <iframe src="http://www.slideshare.net/slideshow/embed_code/9074978" width="425" height="355" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe> <div style="padding:5px 0 12px"> View more <a href="http://www.slideshare.net/" target="_blank">presentations</a> from <a href="http://www.slideshare.net/zainulcharbiwala" target="_blank">Zainul Charbiwala</a> </div> </div> |
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http://nesl.ee.ucla.edu/fw/zainul/CSEC-infocom2010.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/csec-infocom.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/csec-infocom-recording.mov |
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The 29th Conference on Computer Communications (INFOCOM) |
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2010-03-01 |
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San Diego |
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| 2004 |
2 |
4 |
Motivations Behind SOS |
SOS. For those who are seeking the sunny side of the street we have ‘Save Our Sensors’. Individuals seeking a more fundamental approach to life can use ‘Sensor Operating System’. Mathematicians may find amusement in the recursion present in ‘SOS Operating System’. Or choose your own. The possibilities are almost endless. For now, it is simply SOS. |
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http://nesl.ee.ucla.edu/projects/sos-beta/publications/motivation.pdf |
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2004-02-01 |
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| 2008 |
1 |
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Online Calibration |
Time synchronization is an extremely important service in
wireless sensor networks. The notion of time on a node is
maintained using crystal oscillators. These oscillators are
designed to oscillate at a particular frequency called the
nominal frequency, but typically there is always some deviation.
This deviation is caused due to a wide variety of reasons
which include manufacturing variations, environmental
factors such as temperature, pressure, humidity. Even aging
of the crystal is a long-term factor influencing the oscillation
of a crystal. Various time synchronization protocols
have been developed over the years which perform message
exchanges at different points in time to keep the clocks in
sync. These points are called the resynchronization points,
and are essential because in spite of periodic synchronization,
the clocks continue to drift apart with time. One way
to avoid frequent resynchronization is to locally compensate
for the drifts once a synchronization is performed. Ideally,
these drifts are due to a combination of various factors and
we should compensate for each of them. In this report, we
focus on the drift caused due to temperature(which is also
the most dominant factor) and ways to compensate for it.
There are various techniques which have been developed to
perform compensation for temperature induced drifts. The
techniques rely on creation of a look-up table which relates
the different temperature ranges with the corresponding frequency
drifts. Since, this table is highly specific to a crystal,
we need to perform the measurements for the look-up table
during the manufacturing phase of every crystal. Thus, most
of these techniques turn out to be costly.
In this report we try to use the communication network between
nodes, to populate the entries of the look-up table
online. We also exploit the known relationship between frequency
drift and temperature (which is a cubic polynomial)
to estimate the parameters of the polynomial and use it for
local compensation. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2008/onlineCalibration_report_SC.pdf |
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2008-12-01 |
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| 2010 |
1 |
1 |
Biketastic: Sensing and Mapping for Better Biking |
Bicycling is an affordable, environmentally friendly alternative transportation mode to motorized travel. A common task performed by bikers is to find good routes in an area, where the quality of a route is based on safety, efficiency, and enjoyment. Finding routes involves trial and error as well as exchanging information between members of a bike community. Biketastic is a platform that enriches this experimentation and route sharing process making it both easier and more effective. Using a mobile phone application and online map visualization, bikers are able to document and share routes, ride statistics, sensed information to infer route roughness and noisiness, and media that documents ride experience. Biketastic was designed to ensure the link between information gathering, visualization, and bicycling practices. In this paper, we present architecture and algorithms for route data inferences and visualization. We evaluate the system based on feedback from bicyclists provided during a two-week pilot. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_biketastic.pdf |
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ACM Conference on Human Factors in Computing Systems (CHI) |
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2010-04-01 |
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| 2010 |
1 |
2 |
Defect Exposure in Wireless Embedded Systems |
The ability to deploy a Wireless Embedded System (WES) without preexist- ing infrastructure makes it an attractive solution to sensing tasks. Unfortunately, software defects that survive into deployment are challenging to detect and diagnose due to resource constraints, such as low-bandwidth radio-only communications. This dissertation presents two new techniques that help expose defects within WES software. The first technique casts resource usage into an exclusive resource ownership model. The model provides guidelines within which to reason about resources used by their software. Violations to this model are caught at compile time by static analyses that track resource ownership across software component boundaries. The second technique provides a framework for gather- ing compact runtime logs from deployed WESs. This logging technique honors bandwidth limitations of the WES domain by exploiting program structure to create small token name spaces from which token identifiers are assigned. The small token name spaces facilitate compact identifier assignments that that can be efficiently packed into bit aligned data structures. The resulting logs provide developers with much needed insight into runtime WES behavior. |
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http://nesl.ee.ucla.edu/fw/documents/thesis/2010/shea10dissertation.pdf |
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http://nesl.ee.ucla.edu/fw/documents/thesis/2010/shea10defense.pdf |
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Ph.D. Thesis, UCLA CS Department |
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2010-01-01 |
2010-03-01 |
UCLA |
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| 2010 |
1 |
3 |
Recovering Lost Sensor Data through Compressed Sensing |
Data loss in wireless sensing applications is inevitable, both due to communication impairments as well as faulty sensors. We introduce an idea using Compressed Sensing (CS) that exploits knowledge of signal model for recovering lost sensor data. In particular, we show that if the signal to be acquired is compressible, it is possible to use CS not only to reduce the acquisition rate but to also improve robustness to losses.This becomes possible because CS employs randomness within the sampling process and to the receiver, lost data is virtually indistinguishable from randomly sampled data.To ensure performance, all that is required is that the sensor over-sample the phenomena, by a rate proportional to the expected loss.
In this talk, we will cover a brief introduction to Compressed Sensing and then illustrate the recovery mechanism we call CS Erasure Coding (CSEC). We show that CSEC is efficient for handling missing data in erasure (lossy) channels, that it parallels the performance of competitive coding schemes and that it is also computationally cheaper. We support our proposal through extensive performance studies on real world wireless channels.
<br>
<a href=http://nesl.ee.ucla.edu/fw/zainul/csec-seminar-recording.mp3>Talk Audio (mp3)</a>
<br>
<div style="width:425px;text-align:left" id="__ss_2958749"><a style="font:14px Helvetica,Arial,Sans-serif;display:block;margin:12px 0 3px 0;text-decoration:underline;" href="http://www.slideshare.net/zainulcharbiwala/recovering-lost-sensor-data-through-compressed-sensing" title="Recovering Lost Sensor Data through Compressed Sensing">Recovering Lost Sensor Data through Compressed Sensing</a><object style="margin:0px" width="425" height="355"><param name="movie" value="http://static.slidesharecdn.com/swf/ssplayer2.swf?doc=csec-seminar-100120140206-phpapp02&stripped_title=recovering-lost-sensor-data-through-compressed-sensing" /><param name="allowFullScreen" value="true"/><param name="allowScriptAccess" value="always"/><embed src="http://static.slidesharecdn.com/swf/ssplayer2.swf?doc=csec-seminar-100120140206-phpapp02&stripped_title=recovering-lost-sensor-data-through-compressed-sensing" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="355"></embed></object><div style="font-size:11px;font-family:tahoma,arial;height:26px;padding-top:2px;">View more <a style="text-decoration:underline;" href="http://www.slideshare.net/">presentations</a> from <a style="text-decoration:underline;" href="http://www.slideshare.net/zainulcharbiwala">Zainul Charbiwala</a>.</div></div>
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http://nesl.ee.ucla.edu/fw/zainul/csec-seminar.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/csec-seminar-recording.mov |
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CENS Technical Seminar |
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2010-01-01 |
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UCLA |
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#<DocumentCategory:0x007f418cf99e10> |
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| 2010 |
1 |
4 |
High-Resolution, Low-Power Time Synchronization an Oxymoron No More |
<p>
The time synchronization service has become an integral part of sensor network platforms and a lot of resources have been devoted to make it stable and more precise. While recent work improved the per-hop accuracy for long multi-hop networks, it seems that the overall mean accuracy has not been improving below about 1.5us, and low-power high-accuracy time synchronization at that level has been missing altogether. In this paper, we will present two key technologies, Temperature Compensated Time Synchronization, and Virtual High-resolution Time, that allow a 10x improvement in average power draw for duty-cycles <0.1% at a synchronization accuracy of <1us.
</p>
<p>
<object width="400" height="300"><param name="allowfullscreen" value="true" /><param name="allowscriptaccess" value="always" /><param name="movie" value="http://vimeo.com/moogaloop.swf?clip_id=10999698&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1" /><embed src="http://vimeo.com/moogaloop.swf?clip_id=10999698&server=vimeo.com&show_title=1&show_byline=1&show_portrait=0&color=&fullscreen=1" type="application/x-shockwave-flash" allowfullscreen="true" allowscriptaccess="always" width="400" height="300"></embed></object><p><a href="http://vimeo.com/10999698">High-Resolution, Low-Power Time Synchronization an Oxymoron No More</a> from <a href="http://vimeo.com/tschmid">Thomas Schmid</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
</p> |
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http://nesl.ee.ucla.edu/fw/thomas/ipsn763s-schmid.pdf |
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http://nesl.ee.ucla.edu/fw/thomas/ipsn2010-oxymoron.pdf |
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http://nesl.ee.ucla.edu/fw/thomas/ipsn2010-oxymoron.mp4 |
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IPSN <b>[Best Paper Award]</b> |
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2010-04-01 |
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Stockholm, Sweden |
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| 2007 |
6 |
6 |
Must-alias Analysis for C using bddbddb |
This document details using the bddbddb tool, developed by Whaley and Lam, to implement a must-alias analysis for programs written in C. We currently generate and analyze constraints for a subset of C including simple pointer types, dynamic memory management with malloc and free, and if - else statements. We describe potential pathways to supporting a wider subset of C, such as loops and inter-procedural analysis of function calls, with minimal changes to our analysis. More challenging future work includes supporting (potentially recursive) data structures and adding context sensitivity.
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http://nesl.ee.ucla.edu/fw/documents/reports/2007/shea07must.pdf |
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2007-06-01 |
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UCLA |
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#<DocumentCategory:0x007f418d01dd78> |
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| 2010 |
2 |
1 |
Improving Activity Classification for Health Applications on Mobile Devices using Active and Semi-Supervised Learning |
Mobile phones’ increasing ubiquity has created many opportunities for personal context sensing. Personal activity is an important part of a user’s context, and automatically recognizing it is vital for health and fitness monitoring applications. Recording a stream of activity data enables monitoring patients with chronic conditions affecting ambulation and motion, as well as those undergoing rehabilitation treatments. Modern mobile phones are powerful enough to perform activity classification in real time, but they typically use a static classifier that is trained in advance or require the user to manually add training data after the application is on his/her device. This paper investigates ways of automatically augmenting activity classifiers after they are deployed in an application. It compares active learning and three different semi-supervised learning methods, self-learning, En-Co-Training, and democratic co-learning, to determine which show promise for this purpose. The results show that active learning, En-Co-Training, and democratic co-learning perform well when the initial classifier’s accuracy is low (75-80%). When the initial accuracy is already high (90%), these methods are no longer effective, but they do not hurt the accuracy either. Overall, active learning gave the highest improvement, but democratic co- learning was almost as good and does not require user interaction. Thus, democratic co-learning would be the best choice for most applications, since it would significantly increase the accuracy for initial classifiers that performed poorly. |
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http://www.ee.ucla.edu/~sasank/web/doc/sr_pervasivehealth.pdf |
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2010-03-01 |
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ICST Conference on Pervasive Com |
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#<DocumentCategory:0x007f418d0e4630> |
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| 2010 |
3 |
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Scoped Identifiers for Efficient Bit Aligned Logging |
<p> Detailed diagnostic data is a prerequisite for debugging problems
and understanding runtime performance in distributed wireless embedded
systems. Severe bandwidth limitations, tight timing constraints, and
limited program text space hinder the application of standard diagnostic
tools within this domain. This work introduces the Log Instrumentation
Specification (LIS), which provides a high level logging interface to
developers and is able to create extremely compact diagnostic logs. LIS
uses a token scoping technique to aggressively compact identifiers that
are packed into bit aligned log buffers. </p>
<p> LIS is evaluated in the context of recording call traces within a
network of wireless sensor nodes. Our evaluation shows that logs
generated using LIS require less than 50\% of the bandwidth utilized by
alternate logging mechanisms. Through microbenchmarking of a complete
LIS implementation for the TinyOS operating system, we demonstrate that
LIS can comfortably fit onto low-end embedded systems. By significantly
reducing log bandwidth, LIS enables extraction of a more complete
picture of runtime behavior from distributed wireless embedded systems.
</p>
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http://nesl.ee.ucla.edu/fw/documents/conference/2010/shea10scoped.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2010/shea10scopedSlides.pdf |
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DATE |
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2010-03-01 |
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Dresden, Germany |
ACM |
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| 2010 |
4 |
1 |
Design and Implementation of a Robust Sensor Data Fusion System for Unknown Signals |
In this work, we present a robust sensor fusion system for exploratory data
collection, exploiting the spatial redundancy in sensor networks.
Unlike prior work, our system design criteria considers a heterogeneous correlated noise model and packet
loss, but no prior knowledge of
signal characteristics.
The former two assumptions are both common signal degradation sources in sensor
networks, while the latter allows exploratory data collection of unknown
signals.
Through both a numerical example and an experimental study on a large military
site, we show that our proposed system reduces the noise in an unknown signal
by 58.2% better than a comparable algorithm. |
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The 6th IEEE International Conference on Distributed Computing in Sensor Systems (DCOSS '10) |
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2010-06-01 |
2010-06-01 |
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| 2010 |
4 |
2 |
Disentangling Wireless Sensing from Mesh Networking |
The resource demand of complex mesh networking stacks burdens the advancement of low-cost, low-power wireless sensor nodes. Optimizing wireless sensors means reducing costs, increasing lifetimes, and locating sensors close to the action. Adding mesh network func- tions like routing and forwarding increases RAM and ROM requirements and demands substantial idle listen- ing to forward others’ traffic, which add cost and domi- nate the power budget. We argue that an architectural sep- aration between sensor and router, similar to what ZigBee and traditional IP networks advocate, would allow each node class to be better optimized to the task, matched to technology trends, and aligned with deployment pat- terns. Although trivial to implement on current platforms, for example by turning off router advertisements in an IPv6/6LoWPAN stack, reaping the full benefits of this approach requires revising platform decisions and revis- iting the link and network layers of the stack. This work examins the pros and cons such a split offers for wireless sensor network system architectures. |
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HotEmNets |
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2010-06-01 |
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Ireland |
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| 2010 |
5 |
1 |
Towards Design Guidelines for Participatory Sensing Campaigns |
The rapid adoption of mobile phones has enabled a new sensing paradigm - participatory sensing - where individuals act as sensors by using their mobile phones for data collection. Participatory sensing relies on the sensing capabilities and networking support of mobiles phones along with the spatial and temporal coverage and interpretive abilities provided by the individuals that operate them. If successfully coordinated, participants involved in data collection can open up new possibilities in understanding social and physical processes relevant to the interests of individuals, groups, and communities. Realizing a vision of sensing that is widespread and truly participatory poses critical technology challenges. This work details a mechanism to recruit individuals to perform particular data collections. The recruitment framework considers the following elements to select data collectors: (a) the availability of participants in terms of activity, spatial, and temporal contexts, (b) the reputation of participants as data collectors, and (c) the resource and incentive costs associated with participants to enable and motivate contributions. A series of deployments related to sustainability are used to show the utility of the recruitment service. |
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UCLA, PhD Dissertation |
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2010-06-01 |
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| 2010 |
6 |
1 |
Examining Micro-Payments for Participatory Sensing Data Collections |
The rapid adoption of mobile devices that are able to capture and transmit a wide variety of sensing modalities (media and location) has enabled a new data collection paradigm - participatory sensing. Participatory sensing initiatives organize individuals to gather sensed information using mobile devices through cooperative data collection. A major factor in the success of these data collection projects is sustained, high quality participation. However, since data capture requires a time and energy commitment from individuals, incentives are often introduced to motivate participants. In this work, we investigate the use of micro-payments as an incentive model. We define a set of metrics that can be used to evaluate the effectiveness of incentives and report on findings from a pilot study using various micro-payment schemes in a university campus sustainability initiative. |
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International Conference on Ubiquitous Computing (Ubicomp) |
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2010-09-01 |
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| 2010 |
7 |
1 |
A Case Against Routing-Integrated Time Synchronization |
To achieve more accurate global time synchronization, this paper argues for decoupling the clock distribution net- work from the routing tree in a multihop wireless network. We find that both flooding and routing-integrated time synchronization rapidly propagate node-level errors (typically due to temperature fluctuations) across the network. There- fore, we propose that a node chooses synchronization neighbors that offer the greatest frequency stability. We propose two methods to estimate a neighbor’s stability. The first approach selects the neighbor whose frequency error variance is smallest, with respect to the local clock. The second approach selects the neighbor that reports the lowest variance relative to its synchronization parent. We also propose node-level time-variance as an additive metric for selecting more stable clock trees than either naıve flooding or routing- integrated time synchronization can provide. We incorporate these techniques into FTSP, a widely-used time synchronization protocol, and show that the mean error in global time significantly improved (by a factor of five) when some nodes are warmed and others are not. |
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ACM SenSys |
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2010-11-01 |
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Zurich, Switzerland |
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| 2010 |
8 |
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Quality Tradeoffs in Object Tracking with Duty-Cycled Sensor Networks [Best Paper Award] |
Extending the lifetime of wireless sensor networks requires energy-conserving operations such as duty-cycling. How- ever, such operations may impact the effectiveness of high-fidelity real-time sensing tasks, such as object tracking, which require high accuracy and short response times. In this paper, we quantify the influence of different duty-cycle schemes on the bearings- only object tracking efficiency. Specifically, we use the Maximum Likelihood localization technique to analyze the accuracy limits of object location estimates under different response latencies considering variable network density and duty-cycle parameters. Moreover, we study the tradeoffs between accuracy and response latency under various scenarios and motion patterns of the object. We have also investigated the effects of different duty-cycled schedules on the tracking accuracy using acoustic sensor data collected at Aberdeen Proving Ground, Maryland, by the U.S. Army Research Laboratory (ARL). |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2010/zahedi_rtss2010_cameraready.pdf |
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Proceedings the 31st IEEE Real-Time Systems Symposium |
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2010-11-01 |
2010-12-01 |
San Diego, CA |
IEEE |
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| 2010 |
8 |
2 |
A Case for Opportunistic Embedded Sensing In Presence of Hardware Power Variability |
The system lifetime gains provided by the various power management techniques in embedded sensing systems are a strong function of the active and sleep mode power consumption of the underlying hardware platform. However, power consumption characteristics of hardware platforms exhibit high variability across different instances of the platform, diverse ambient conditions, and over passage of time. The factors underlying this variability include increased manufacturing variations and aging effects due to shrinking transistor geometries, and deployment of embedded devices in extreme environments. Our experimental measurements show that large variability in sleep mode power is already present in commonly used embedded processors, and technology trends suggest that the variability will grow even more over time and affect active mode power as well. Such variability results in suboptimal lifetime and service quality. We therefore argue for energy management approaches that learn and model the power characteristics of the specific instance of the hardware platform, and adapt accordingly. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2010/wanner_hotpower10_final.pdf |
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Proceedings of the 2010 Workshop on Power Aware Computing and Systems (HotPower '10) |
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2010-10-01 |
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Vancouver, Canada |
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| 2010 |
9 |
2 |
Granger Causality Analysis on IP Traffic and Circuit-Level Energy Monitoring |
Device-level energy monitoring has been increasingly proposed to understand inefficient energy use and design systematic processes for efficient building operation. Its sole use, however, is not sufficient to provide actionable information unless we understand the causes and context of energy
use.
Fundamentally, energy consumption in a building is due to occupants’ various activities. Understanding the causal relationship between occupants and their energy use is thus the key to an efficient building operation. This usually involves fine-grained sensing through intensive instrumentation of individual
power outlets and/or extensive user studies that either increase the system cost or become too intrusive.
Instead, we advocate that circuit branch level energy monitoring combined with statistical Granger causality analysis is adequate to automatically understand the causal relationship. We monitor energy consumption of various zones in an office using a circuit level power monitor. IP traffic from users’ PCs, obtained from a local firewall, is used to relate occupants with their energy use in each micro zone. The
output is expressed in the form of causality graphs that illustrate how each individual influences energy use in different zones. We discuss the effectiveness and limitations of this causal analysis in capturing energy use patterns of the occupants in a lab environment. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2010/younghun_buildsys2010.pdf |
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Second ACM Workshop On Embedded Sensing Systems For Energy-Efficiency In Buildings (BuildSys) |
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2010-11-01 |
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Zurich, Switzerland |
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| 2010 |
10 |
1 |
SensorSafe: Privacy-Preserving Sharing of Sensory Information for Medical Studies and Healthcare |
In medical studies and mobile healthcare services, sharing of personal sensory information is inevitable. While we need to share such information, it is important to preserve privacy of individuals. The key challenge is balancing individual privacy and information utility. That is achieving a certain utility of the information while restricting or hiding sensitive information from personal data. We propose a privacy-preserving data sharing architecture to solve the problem. Our architecture provides several mechanisms: fine-grained access control, remote data stores, data obfuscation, and utility assessment. With our privacy mechanisms, individual can obtain control over who can access what information, choose where their data are physically stored, and restrict inferences that can be drawn using their data. In addition, using our utility assessment tool, medical study organizers can find study subjects who provide desired quality of information. |
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http://nesl.ee.ucla.edu/fw/documents/posters/2010/choi-cens-arr.pdf |
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Center for Embedded Networked Sensing (CENS) 8th Annual Research Review |
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2010-10-01 |
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| 2010 |
10 |
2 |
A Unified CAD-PLM Architecture for Improving Electronics Design Productivity through Automation, Collaboration, and Cloud Computing. |
Computer Aided Design (CAD) tools have all but eliminated manual drafting and for good reason. CAD offers more accurate drawing tools, grey coding of drafting symbols, rapid duplication of finished designs, easier integration with manufacturing partners, and automated design rule verification. For the purposes of this work we focus on electronics design. CAD tools in this space manage part data in a logical schematic view (a part symbol) and a physical PCB view (a part footprint). Yet, a part has a third view, which CAD tools ignore – it’s supply data (Manufacturer part number, variant, distributor, etc).
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To manage this manufacturing view a broad class of tools known as Product Lifecycle Management (PLM) have evolved to include most of the functions previously classified as Engineering Resource Planning (ERP). AMR Research analyst Michael Burkett describes it this way, "PLM is [no longer] a single application but a process that crosses multiple business processes and technologies, i.e. marketing and supply chain.”
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Despite these advances, a substantial chiasm still exists between the manufacturing and engineering views. More specifically, part data known to the supply chain (managed through PLM tools) and performance and specification data known to the engineering world (managed through CAD tools) must be manually integrated and managed by the design team.
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This leads to a substantial amount of redundant data entry into both tool chains with any error resulting in an inconsistency between design intent and fabrication. In the case of electronic small parts, this can result in subtle (even unnoticeable) part substitutions which may yield dramatic product performance alterations.
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In this work we introduce an entirely new approach to bridging the tool-chain divide – a web-based architecture we call FriedParts. FriedParts exploits the recently available database-driven parametric part interfaces of CAD tools (like Cadence’s Component Information System or Altium’s Database Library Components) and web 2.0 automation to crawl data information providers like Octopart, Inc. and Digikey, Inc. and tie this information directly into the CAD tool at design time. It uses heuristics to suggest CAD symbols and footprints. Part search is handled from the website where cloud computing accelerates the search performance. The materials bill output from the CAD tool is then fed back into FriedParts which can automatically find second-source distribution, find alternate manufacturers, optimize purchasing, and perform other PLM functions. The amount of data entry by the designer is brought to almost zero. FriedParts stores the actual CAD data (part libraries) fostering verification and collaboration. FriedParts is open-source and will be made available as a free service. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/friedman-friedparts-ipc-apex.pdf |
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Association Connecting Electronics Industries (IPC) APEX Conference Proceedings |
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9 |
2011-04-01 |
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Las Vegas, NV USA |
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| 2010 |
11 |
1 |
Variability-Aware Duty Cycle Scheduling in Long Running Embedded Sensing Systems |
Instance and temperature-dependent leakage power variability is already a significant issue in contemporary embedded processors, and one which is expected to increase in importance with scaling of semiconductor technology.
We measure and characterize this leakage power variability in current microprocessors, and show that variability aware duty cycle scheduling produces 7.8x improvement in sensing quality for a desired lifetime. In contrast, pessimistic estimations of power consumption leave 61% of the energy untapped, and datasheet power specifications fail to meet required lifetimes by 15%. Finally, we introduce a duty cycle abstraction for TinyOS that allows applications to explicitly specify lifetime and minimum duty cycle requirements for individual tasks, and dynamically adjusts duty cycle rates so that overall quality of service is maximized in the presence of power variability. |
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http://nesl.ee.ucla.edu/~neslfw/documents/conference/2010/wanner_date11_final.pdf |
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Proceedings of Design, Automation and Test in Europe 2011 (DATE) |
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5 |
2011-03-01 |
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Grenoble, France |
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| 2011 |
1 |
1 |
Programming Support for Distributed Optimization and Control in Cyber-Physical Systems |
Large-scale actuator control problems in Cyber-Physical Systems (CPSs) are often expressed within the networked optimization model. While significant advances have taken place in optimization techniques, their widespread adoption in practical implementations is impeded by the complexity of inter-node coordination and lack of programming support that is necessary for sharing information coherently between distributed and concurrent controller processes. In this paper, we propose a distributed shared memory (DSM) architecture that abstracts away the details of inter-node coordination from the programmer resulting in simplified application design. It maintains data coherency through explicit use of mutual exclusion lock primitives that serialize access to coarse subsets of shared variables using fine-grained read/write permissions. The underlying lock protocol is deadlock-free, fair and safe, and reduces response time and message cost by 81.6% and 72.8% respectively over a conventional DSM implementation with coarse access permissions. Moreover, in a representative application example, the proposed framework reduces application code size by 76% and total latency by 22% over a hand-crafted implementation. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/Balani-hotline-iccps-ext.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Balani_Hotline_slides.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Balani_Hotline_slides_with_audio.mov |
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Second International Conference on Cyber-Physical Systems (ICCPS) |
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10 |
2011-04-01 |
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Chicago, USA |
ACM/IEEE |
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| 2011 |
11 |
5 |
Design and Evaluation of SensorSafe: a Framework for Achieving Behavioral Privacy in Sharing Personal Sensory Information |
Continuous collection of sensory information using smartphones and body-worn sensors is now feasible with recent advancement of technologies. Sharing such personal information enables many useful applications such as medical behavioral studies, personal health-care, and participatory sensing. However, sharing such information along with inferences that can be drawn from the data increases user’s various privacy concerns. This paper proposes SensorSafe, an application framework that enables users to share adequate amounts of their private data and supports obfuscation of sensitive information to protect user privacy. Our framework provides rule-based sharing with context-awareness and conflicting rule detection. In addition, our framework includes several optimization techniques for database processing of rule-based sharing and data obfuscation. We evaluate the optimization techniques with a large amount of accelerometer data from the fine-grained posture recognition application, which is about 6.25 GB. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/choi-spiot-trustcom.pdf |
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The 2nd IEEE International Symposium on Security and Privacy in Internet of Things |
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2012-06-01 |
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| 2010 |
11 |
2 |
Submerged Biomimetic Electrostatic Imaging in Salt Water |
Navigation, localization, and targeting while completely submerged
in the ocean are all extremely difficult due to the lack of a proficient
sensor. The highly conductive nature of salt-water results in severe
radio-wave attenuation precluding the use of RADAR. Naturally-
occurring noise sources, high energy costs, long-wavelengths, and
surface turbidity restrict the use of SONAR imaging to low-
resolutions, depths, and far-fields. The ocean’s dark, turbulent, and
silty disposition impedes optical imaging. In this work, we summarize
our latest experimental findings in creating an engineered sensor
which mirrors the biological phenomenon of electroreception and
demonstrate its ability to “visualize” targets with different con-
ductivities from the background ocean environment at very high
resolution by detecting perturbations in a quasi-static electric field
(electrostatics).
Our original work [3] covered the theory and feasibility of
biomimetic electroreception, but contained no practical demonstration
due to the absence of a fabricated prototype to evaluate. We have
recently completed such a device along with the construction of the
relevant instrumentation to evaluate it. Accordingly, we believe that
this work contains the first report and demonstration of a multichannel
electroreceptive sensor array capable of creating Biomimetic Electro-
static Images (BEI). |
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http://nesl.ee.ucla.edu/fw/documents/conference/2010/friedman_Sensors10.pdf |
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http://nesl.ee.ucla.edu/fw/documents/conference/2010/friedman_Sensors10_poster.pdf |
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The 9th Annual IEEE Conference on Sensors |
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4 |
2010-11-01 |
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Waikoloa Village, Hawaii, USA |
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| 2011 |
1 |
2 |
Demystifying Privacy In Sensory Data: A QoI based approach |
There is a growing consensus regarding the emergence of privacy concerns as a major deterrent towards the widespread adoption of emerging technologies such as mobile healthcare, participatory sensing and other social network based applications. In this paper, we motivate the need for privacy awareness, present a taxonomy of the privacy problems, and the various existing solutions. We highlight the tension that exists between quality of service at the receiver and the privacy requirement at the source and present a linear program formalization to model the tradeoff between the two objectives. We further present the design and architecture of SensorSafe, a framework which allows privacy-aware sharing of sensory information. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/chakraborty-iq2s.pdf |
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The 3rd International Workshop on Information Quality and Quality of Service for Pervasive Computing |
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6 |
2011-03-01 |
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Seattle, WA |
IEEE |
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#<DocumentCategory:0x007f418d7348c8> |
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| 2010 |
9 |
3 |
Acoustic and Optical Communication for Underwater Wireless Sensor Networks |
Underwater Sensor Networks (USN) have been of growing interest in recent years. USN are envisioned to monitor pollution and harmful algal blooms, provide an early warning for natural disasters, aid in surveillance applications for defense purposes, and assist in finding and recovering wrecked ships and aircrafts. Most USN require wireless communication and currently acoustics is the primary modality of choice even though it presents a difficult channel. To try and cope with the challenges of the channel many MAC protocols and PHY layer techniques have been proposed. In this thesis the author presents a research platform that al- lows developers to easily implement and compare their protocols in an underwater network and configure them at runtime. The platform was created using widely supported software that has been successfully used in terrestrial radio and net- work development. The flexibility of development tools such as software defined radio have provided the ability for rapid growth in the community. This platform adapts some of these tools to work well with the underwater environment while maintaining flexibility, ultimately providing an end-to-end networking approach for underwater acoustic development. The author has demonstrated how this platform can be used by developing a protocol for underwater dynamic channel assignment in USNs.
In addition to developing a highly configurable acoustic modem, this thesis also introduces a card based design for optical communication. Optics is used for a low power, short distance alternative to the high power acoustics. Both platforms have been demonstrated in real world scenarios and can be controlled from an embedded Linux platform allowing for a single application to have access to both modalities simultaneously. |
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http://nesl.ee.ucla.edu/~neslfw/documents/thesis/2010/2010_09_ms_DT.pdf |
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MS Thesis, UCLA Electrical Engineering Department |
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65 |
2010-09-01 |
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Los Angeles |
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| 2011 |
3 |
1 |
Arrhythmia Detection System using the Data-Flow Architecture1 |
In recent days, smartphones offer more advanced computing ability and connectivity than in the past. A smartphone has a lot of on-the-phone sensors, such as GPS, accelerometer, microphone, camera etc. In addition, a smartphone application can employ remote wireless body sensors, such as electrocardiogram (ECG) sensors or temperature skin sensors to track a user’s behavior and provide useful information for his health. There have been studies where a smartphone was tracking the sensor’s raw data and was processing them on the phone-side. However, now we can use “smart” sensors, which can do some computation on sensor-side and feed the smartphone with processed data. In such a way, the overall performance will be better as some computation would be done much closer to the hardware (on sensor-side).
In this paper, the design of a dynamic, data-flow architecture for extracting context-aware information is presented. In the proposed design, the whole process of tracking and handling the sensor’s data is provided to the smartphone’s applications as a Data-Flow Service and is totally separated from the smartphone’s application itself. The user can remotely turn-on/off the sampling of the sensor’s signal and dynamically choose whether the computation will be done on the sensor-side or on the phone-side.
In order to present the data-flow architecture, an application on Android HTC Wildfire has been implemented. It uses the DFS, tracks ECG data from a remote ECG sensor and determines if the user has arrhythmia or not. |
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http://nesl.ee.ucla.edu/fw/zafeiria/report.pdf |
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http://nesl.ee.ucla.edu/fw/zafeiria/presentation.pptx |
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10 |
2011-03-01 |
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Zafeiria Anagnostopoulou |
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| 2011 |
3 |
2 |
Network Services for Mobile Participatory Sensing |
The rapid explosion of mobile phones over the last decade has enabled a new sensing paradigm – participatory sensing – where individuals act as sensors by using their mobile phones for data collection. Participatory sensing relies on the sensing capabilities of mobile phones, many of which have the ability to detect location, capture images and audio, the networking support provided by cellular and WiFi infrastructure, and the spatial and temporal coverage along with interpretive abilities provided by the individuals that carry and operate mobile phones. If successfully coordinated, participants involved in data collection using their mobile phones can open up new possibilities uniquely relevant to the interests of individuals, groups, and communities as they seek to understand the social and physical processes of the world around them. Responsibly realizing a vision of sensing that is widespread and participatory poses critical technology challenges. To support mobile participatory sensing applications, the future Internet architecture must provide network services that enable applications to select, task, and coordinate mobile users based on measures of coverage, capabilities and participation and performance patterns; attestation mechanisms that enable sensor data consumers to assess trustworthiness of the data they access; and privacy and auditing mechanisms that enable sensor sources to control sharing and disclosure of data. |
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Emerging Wireless Technologies and the Future Mobile Internet (ed. Dipankar Raychaudhuri and Mario Gerla) |
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154 |
177 |
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2011-03-01 |
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Cambridge University Press |
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#<DocumentCategory:0x007f418d22fcd8> |
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| 2011 |
4 |
4 |
OppSense: Information Sharing for Mobile Phones in Sensing Field with Data Repositories |
With the popularity and advancements of smart phones, mobile users can interact with the sensing facilities and exchange information with other wireless devices in the environment by short range communications. Opportunistic exchange has recently been suggested in similar contexts; yet we show strong evidence that, in our application, opportunistic exchange would lead to insufficient data availability and extremely high communication overheads due to inadequate or excessive human contacts in the environment.
In this paper, we present OppSense, a novel design to provide efficient opportunistic information exchange for mobile phone users in sensing field with data repositories that tackles the fundamental availability and overhead issues. Our design differs from conventional opportunistic information exchange in that it can provide mobile phone users guaranteed opportunities for information exchange regardless the number of users and contacts in different environments. Through both analysis and simulations, we show that the deployment of data repositories plays a key role in the overall system optimization. We demonstrate that the placement of data repositories is equivalent to a connected K-coverage problem, and an elegant heuristic solution considering the mobility of users exists. We evaluate our proposed framework and algorithm with real mobile traces. Extensive simulations demonstrate that data repositories can effectively enhance the data availability up to 41% in low contact environment and significantly reduce the communication overheads to only 28% compared to opportunistic information exchange in high contact environment. |
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Proceedings of the Eighth Annual IEEE Communications Society Conference on Sensor, Mesh, and Ad Hoc Communications and Networks (SECON 2011) |
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9 |
2011-06-01 |
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Salt Lake City, Utah, USA |
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| 2011 |
4 |
2 |
Privacy Risks Emerging from the Adoption of Innocuous Wearable Sensors in the Mobile Environment |
Wearable sensors are revolutionizing healthcare and science by enabling capture of physiological, psychological, and behavioral measurements in natural environments. However, these seemingly innocuous measurements can be used to infer potentially private behaviors such as stress, conversation, smoking, drinking, illicit drug usage, and others. We con- ducted a study to assess how concerned people are about disclosure of a variety of behaviors and contexts that are embedded in wearable sensor data. Our results show participants are most concerned about disclosures of conversation episodes and stress — inferences that are not yet widely publicized. These concerns are mediated by temporal and physical context associated with the data and the participant’s personal stake in the data. Our results provide key guidance on the extent to which people understand the potential for harm and data characteristics researchers should focus on to reduce the perceived harm from such datasets. |
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Proceedings of the ACM CHI Conference on Human Factors in Computing Systems |
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10 |
2011-05-01 |
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Vancouver, Canada |
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#<DocumentCategory:0x007f418cf7cb58> |
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| 2012 |
7 |
3 |
Subjective Logic with Uncertain Partial Observations |
Subjective logic (SL) is an effective tool to manage and update beliefs over a set of mutually exclusive assertions. The method to update subjective beliefs from direct observations of assertions is well understood. Recent work has incorporated the SL framework to derive the belief update equations for partial observations where the measurements are only statistically related to the assertions. This work further expands the notion of SL to consider uncertainty in the underlying statistical relation- ship between measurements and assertions. In other words, new methods are derived for SL that incorporate uncertainty in the reported likelihood of the assertions. Simulations demonstrate the utility of the new likelihood uncertainty aware belief update methods. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/Kaplan-SL_Partial.pdf |
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Proceedings of the 5th International Conference on Information Fusion (Fusion 2012) |
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8 |
2012-07-01 |
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Singapore |
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#<DocumentCategory:0x007f418cbb0920> |
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| 2011 |
4 |
3 |
Distributed Coordination for Fast Iterative Optimization in Wireless Sensor/Actuator Networks |
Large-scale coordination and control problems in sensor/actuator networks are often expressed within the networked optimization model. While significant advances have taken place in both first- and higher-order optimization techniques, their widespread adoption in practical implementations has been hindered by a lack of adequate programming and evaluation support. This motivates the two major contributions of this paper. First, we outline the design of an Application Programming Framework, implement different versions of the subgradient technique and perform extensive evaluation with varying deployment and algorithmic parameters. Second, the insights obtained by observing the variability in practical metrics such as response time and incurred message cost, lead us to exploit the spatial locality inherent in these large-scale actuator control applications, and propose a novel consensus algorithm applied to the subgradient method. We show using simulations that there is at least 99% improvement in response time and the message cost is reduced by more than 90% over prior consensus based algorithms. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/Balani-secon.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Balani_SECON_slides.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Balani_SECON_audio_slides.mov |
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Proceedings of the Eighth Annual IEEE Communications Society Conference on Sensor, Mesh, and Ad Hoc Communications and Networks (SECON) |
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9 |
2011-06-01 |
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Salt Lake City, Utah, USA |
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| 2011 |
4 |
1 |
Compressive Sensing of Neural Action Potentials Using a Learned Union of Supports |
Wireless neural recording systems are subject to stringent power consumption constraints to support long-term recordings and to allow for implantation inside the brain. In this paper, we propose using a combination of on-chip detection of action potentials (“spikes”) and compressive sensing (CS) techniques to reduce the power consumption of the neural recording system by reducing the power required for wireless transmission. We empirically verify that spikes are compressible in the wavelet domain and show that spikes from different neurons acquired from the same electrode have subtly different sparsity patterns or supports. We exploit the latter fact to further enhance the sparsity by incorporating a union of these supports learned over time into the spike recovery procedure. We show, using extracellular recordings from human subjects, that this mechanism improves the SNDR of the recovered spikes over conventional basis pursuit recovery by up to 9.5 dB (6 dB mean) for the same number of CS measurements. Though the compression ratio in our system is contingent on the spike rate at the electrode, for the datasets considered here, the mean ratio achieved for 20-dB SNDR recovery is improved from 26:1 to 43:1 using the learned union of supports.
<hr>
<a href=/fw/zainul/bsn2011_code.tgz>Code</a> (with dependent libraries - 28MB)
<br>
<a href=/fw/zainul/bsn2011_data.tgz>Data</a> (unprocessed - 47MB)
<hr>
<div style="width:425px" id="__ss_9074047"> <strong style="display:block;margin:12px 0 4px"><a href="http://www.slideshare.net/zainulcharbiwala/bsn2011" title="Compressively Sensing Action Potentials (Neural Spikes) - Presented at BSN 2011" target="_blank">Compressively Sensing Action Potentials (Neural Spikes) - Presented at BSN 2011</a></strong> <iframe src="http://www.slideshare.net/slideshow/embed_code/9074047" width="425" height="355" frameborder="0" marginwidth="0" marginheight="0" scrolling="no"></iframe> <div style="padding:5px 0 12px"> View more <a href="http://www.slideshare.net/" target="_blank">presentations</a> from <a href="http://www.slideshare.net/zainulcharbiwala" target="_blank">Zainul Charbiwala</a> </div> </div>
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http://nesl.ee.ucla.edu/fw/zainul/bsn2011.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/bsn2011_slides.pdf |
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http://nesl.ee.ucla.edu/fw/zainul/bsn2011_recording.mp4 |
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Proceedings of the International Conference on Body Sensor Networks (BSN 2011) |
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6 |
2011-05-01 |
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Dallas, TX |
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| 2011 |
6 |
1 |
SensorSafe: a Framework for Privacy-Preserving Management of Personal Sensory Information |
With the wide-spread use of mobile smartphones and body- worn sensors, continuous collection of sensor data about individuals becomes feasible, and many useful applications such as medical behavioral studies, personal health-care, and participatory sensing have emerged. Such applications have important privacy implications due to their nature of shar- ing personal sensor data. In addition, what is shared is not only the raw sensor data but also the information that can be inferred from the data, which raises more privacy concerns of users. This paper proposes SensorSafe, an ar- chitecture for managing such personal sensory information in a privacy-preserving way. Our architecture consists of multiple remote data stores and a broker so users can re- tain the ownership of their data and management of mul- tiple users can be well supported. SensorSafe also provides a fine-grained access control mechanism by which users can define their own sharing rules based on various conditions including context and behavioral status. Users define their privacy preferences and review their data by using our web- based user interface. We discuss our implementation of the SensorSafe architecture and provide application examples to show how our system can support user privacy. Our perfor- mance evaluation results demonstrate that building appli- cations using the SensorSafe architecture is feasible so user privacy can be better protected. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/choi-sdm-vldb.pdf |
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The 8th VLDB Workshop on Secure Data Management |
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2011-06-01 |
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| 2011 |
4 |
6 |
Neighborhood Based Fast Graph Graph Search in Large Networks |
Complex social and information network search becomes impor-
tant with a variety of applications. In the core of these applications,
lies a common and critical problem: Given a labeled network and
a query graph, how to efficiently search the query graph in the tar-
get network. The presence of noise and the incomplete knowledge
about the structure and content of the target network make it unre-
alistic to find an exact match. Rather, it is more appealing to find
the top-k approximate matches.
In this paper, we propose a neighborhood-based similarity mea-
sure that could avoid costly graph isomorphism and edit distance
computation. Under this new measure, we prove that subgraph sim-
ilarity search is NP hard, while graph similarity match is polyno-
mial. By studying the principles behind this measure, we found an
information propagation model that is able to convert a large net-
work into a set of multidimensional vectors, where sophisticated
indexing and similarity search algorithms are available. The pro-
posed method, called Ness (Neighborhood Based Similarity Search),
is appropriate for graphs with low automorphism and high noise,
which are common in many social and information networks. Ness
is not only efficient, but also robust against structural noise and in-
formation loss. Empirical results show that it can quickly and accu-
rately find high-quality matches in large networks, with negligible
cost. |
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2011 ACM SIGMOD |
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2011-06-01 |
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| 2010 |
9 |
4 |
Source Localization by Combining Obfuscated Sensor Reports Using Dempster-Shafer Theory |
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Annual Conference of the ITA , September 2010 |
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2010-09-01 |
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| 2011 |
7 |
1 |
Filters That Remember: Duty Cycling Analog Circuits for Long Term Medical Monitoring |
With recent improvements in the energy efficiency of digital microprocessors and radio transceivers, the relative contribution of the analog front end in the overall power consumption of a wireless health system has been steadily rising. A key reason for this is that sampling rates in most medical applications are extremely low, providing opportunities to aggressively duty cycle the power hungry processor and radio. Analog front ends have not traditionally been duty cycled because analog filters with large time constants dictate a prohibitively high wake up latency. In this paper, we show that this latency can be reduced to a large extent and duty cycling made feasible by making filters “remember” their state across power gating cycles. This is done using slight hardware modifications that can even be applied to existing boards. We illustrate our technique on a commercially available wireless electro-cardiography system. Using our methodology, we reduced the restart delay of the circuit by three orders of magnitude from 6s to 5ms. We employ our circuit design for energy efficient QRS complex detection and extraction, which results in a 3× reduction in analog front end energy consumption. |
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http://nesl.ee.ucla.edu/fw/zainul/FTR_WH11_Zainul.pdf |
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Wireless Health 2011 |
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2011-10-01 |
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San Diego, CA |
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| 2011 |
7 |
2 |
Nordic Radio nRF24L01+ Power Characterization |
Abstract This document presents results from our experiments with the Nordic nRF24L01+ radio transceiver. We characterize the radio in terms of its power consumption under various conditions for ECG sensing using 5 different techniques with varying degrees of computational expenditure. |
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http://nesl.ee.ucla.edu/fw/zainul/NordicRadio.pdf |
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2011-07-01 |
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| 2011 |
8 |
1 |
Cooperative State Estimation for Preserving Privacy of User Behaviors in Smart Grid |
Smart grid promises a reliable and secure electricity infrastructure to meet the future demand growth. However, the increase of data types and data amount from advanced smart grid introduce new privacy issues, which have to be resolved for customers. This paper presents a cooperative state estimation technique that protects the privacy of users’ daily activities. By exploiting the kernel of an electric grid configuration matrix, we develop an error free state estimation technique that can hide the behavioral information of users effectively. The proposed scheme can obfuscate the privacy-prone data without compromising the performance of state estimation. We evaluate our obfuscation scheme using data from 1349 meters in 5 IEEE Electric Test Bus Systems. Our simulation results demonstrate high level of illegibility and resilience of our scheme with an affordable communication overhead. |
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Proceedings of the 2nd IEEE International Conference on Smart Grid Communications (SmartGridComm 2011) |
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2011-10-01 |
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Brussels, Belgium |
IEEE |
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| 2011 |
11 |
1 |
Qualcomm Weekly Review |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Supriyo_QInF21Oct.pdf |
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2011-11-01 |
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| 2011 |
8 |
3 |
A 16-Electrode Biomimetic Electrostatic Imaging System for Ocean Use |
A compilation of our latest design, simulation, and evaluation efforts regarding the construction of a biomimetic electrostatic imaging platform capable of visualizing submerged objects in a salt-water environment. In our previous work, the position accuracy was no better than 10cm. The imager described here achieves 2.5cm accuracy on the center line and degrades to 5cm accuracy at the peripheral channels. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/friedman-sensors.pdf |
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International Conference on Sensors and Sensor Systems (IEEE SENSORS) |
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4 |
2011-10-01 |
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Limerick, Ireland |
IEEE |
true |
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| 2011 |
10 |
1 |
A Biomimetic Electrostatic Imaging System Proposed for Real-Time In-Vivo Surgical Guidance of Tumor Resection |
<p>The surgical isolation and resection of tumor cells is confounded by the shared origin of abhorrent and normal tissue. The cells appear similar under visual inspection and tumor boundaries occur on a scale beneath the limits of human hand manipulation. As a result, modern surgical practice involves the use of resonant and functional imaging to identify the boundaries pre-operatively and then register this prior visualization against the patient intra-operatively (a few recently constructed facilities allow the patient to be moved back and forth via a co-located MRI system). In either case, surgical conservatism results in additional tissue loss than might otherwise be necessary. What is needed is high-resolution spatio-temporal guidance for the removal of tumor tissue that can operate in-vivo, in real time, without precluding simultaneous surgical action.</p>
<p>In this work we discuss our development efforts towards an active electric field-based imaging system, which was inspired by study and replication of the electroreceptive organ systems of certain fish species. These fish are able to discern the presence of objects in their surrounding environment by the perturbation those objects introduce to their emitted electric field. In essence, they are imaging the conductivity variations. Cancer cells are less electrically active than normal brain tissue and, it is proposed, that they can be identified and isolated in the same manner. Our Biomimetic Electrostatic Imaging (BEI) system is under development to provide the desired real-time navigation for surgical resection of brain and other cancerous tumors.</p>
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http://nesl.ee.ucla.edu/fw/documents/posters/2011/JF_PSOC_USC_Poster_48x36.pdf |
http://nesl.ee.ucla.edu/fw/documents/posters/2011/JF_PSOC_USC_Poster_48x36.ppt |
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Physical Sciences in Oncology Center Short Course |
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2011-10-01 |
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Center for Applied Molecular Med |
University of Southern California (USC) |
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true |
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| 2011 |
10 |
2 |
Hardware Variability-Aware Duty Cycling for Embedded Sensors |
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http://nesl.ee.ucla.edu/fw/documents/posters/2011/LW_VarNSF_DutyCycle.pdf |
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Variability Expedition NSF Site Visit |
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2011-10-01 |
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| 2011 |
10 |
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Molecule: An Experimental Testbed for Variability Studies |
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http://nesl.ee.ucla.edu/fw/documents/posters/2011/LW_VarNSF_Molecule.pdf |
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Variability Expedition NSF Site Visit |
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2011-10-01 |
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| 2011 |
10 |
4 |
Low-cost Disaggregation of Sub-system Power |
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http://nesl.ee.ucla.edu/fw/documents/posters/2011/YS_VarNSF_Disagreggation.pdf |
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Variability Expedition NSF Site Visit |
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2011-10-01 |
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#<DocumentCategory:0x007f418cecc348> |
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| 2011 |
10 |
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Virtualization-based Testbed For Variability-Aware Software |
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http://nesl.ee.ucla.edu/fw/documents/posters/2011/LW_VarNSF_Virtualization.pdf |
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Variability Expedition NSF Site Visit |
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2011-10-01 |
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#<DocumentCategory:0x007f418d8f6a30> |
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| 2012 |
7 |
4 |
Balancing Value and Risk In Information Sharing Through Obfuscation |
Fast-paced data-to-decision systems are heavily de- pendent on the reliable sharing of sensor-derived information. At the same time a diverse collection of sensory information providers would want to exercise control over the information shared based on their perception of the risk of possible misuse due to sharing and also depending on the consumer requirements. To attain this utility vs. risk trade-off, information is subjected to varying but deliberate quality modifying transformations which we term as obfuscation. In this paper, treating privacy as the primary motivation for information control, we highlight initial considerations of using feature sharing as an obfuscation mechanism to control the inferences possible from shared sensory data. We provide results from an activity tracking scenario to illustrate the use of feature selection in identifying the various trade-off points. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/supriyo-fusion.pdf |
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Proceedings of the 5th International Conference on Information Fusion (Fusion 2012) |
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8 |
2012-07-01 |
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Singapore |
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#<DocumentCategory:0x007f418cc12940> |
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| 2011 |
10 |
6 |
Hardware Variability-Aware Duty Cycling for Embedded Sensors |
Instance and temperature-dependent power variation has a direct impact on quality of sensing for battery-powered long-running sensing applications. We measure and characterize the active and leakage power for an ARM Cortex M3 processor and show that, across a temperature range of 20 -60, there is a 10% variation in active power, and a variation in leakage power. We introduce variability-aware duty cycling methods and a duty cycle (DC) abstraction for TinyOS which allows applications to explicitly specify the lifetime and minimum DC requirements for individual tasks, and dynamically adjusts the DC rates so that the overall quality of service is maximized in the presence of power variability. We show that variability-aware duty cycling yields a improvement in total active time over schedules based on worst case estimations of power, with an average improvement of across a wide variety of deployment scenarios based on the collected temperature traces. Conversely, datasheet power specifications fail to meet required lifetimes by 7%-15%, with an average 37 days short of the required lifetime of 1 year. Finally, we show that a target localization application using variability-aware DC yields a 50% improvement in quality of results over one based on worst case estimations of power consumption. |
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http://nesl.ee.ucla.edu/fw/documents/journal/2011/LW_TVLSI_Var-Aware-DC.pdf |
http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6232468 |
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IEEE Transactions on VLSI Systems |
21 |
6 |
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1000 |
1012 |
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2013-06-01 |
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IEEE |
false |
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#<DocumentCategory:0x007f418d625090> |
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| 2011 |
9 |
1 |
Design and Implementation of Monitoring and Actuation Platform for Energy Management in Office |
<p>Although the HVAC (Heating, Ventilation and Cooling) systems dominate the
total power consumption of modern buildings, the IT equipments from PCs to
network and server equipments are becoming an increasing contributor to energy
bills and carbon emissions. Recent study also shows that much of the energy
consumption is due to the IT infrastructure. In a typical office where desktop
computers make up a substantial component of working area, the energy savings
would have been potentially remarkable if users could be made aware of energy
using as well as wasting, and an effective strategy was employed to intelligently
control these computers.</p>
<p>In this thesis, we propose a monitoring and actuation platform to address
this issue. Our platform is essentially a system that incorporates several function
modules including data sampling, data visualization, notification, analysis and
control. The contribution of our platform can be divided into two aspects. One
is that we organize meter/sensor data stream efficiently and present them in
a way that clients can easily access them. The other is that we analyze the meter/sensor data and build an effective profile model for each user to predict the subjects activities, and further control subjects computer accordingly to reduce unnecessary energy waste. We demonstrate that our approach achieve a 12% energy savings on average. In addition, the rate of accuracy for prediction of occupant activities using our model reaches approximately 90%.</p> |
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http://nesl.ee.ucla.edu/~neslfw/documents/thesis/2011/Han_Zhao_Master_Thesis_2011_09.pdf |
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http://nesl.ee.ucla.edu/~neslfw/documents/slides/2011/Han_Zhao_Master_Thesis_Slides_2011_09.pdf |
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MS Thesis, UCLA Electrical Engineering Department |
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50 |
2011-09-01 |
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Los Angeles |
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#<DocumentCategory:0x007f418d185710> |
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| 2010 |
10 |
3 |
Physiological Data Collection on Mobile Devices |
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http://nesl.ee.ucla.edu/fw/documents/posters/2010/han-cens-arr.pdf |
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Center for Embedded Networked Sensing (CENS) 8th Annual Research Review |
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2010-10-01 |
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true |
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#<DocumentCategory:0x007f418d1e2e60> |
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| 2011 |
10 |
7 |
SensorSafe: Framework for Sharing Personal Sensory Information with Privacy |
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http://nesl.ee.ucla.edu/fw/documents/reports/2011/haksoo-sensorsafe-ipsn.pdf |
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2011-10-01 |
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#<DocumentCategory:0x007f418c89dbe8> |
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| 2013 |
5 |
1 |
Middleware for Pervasive Sensing and Actuation |
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https://docs.google.com/file/d/0BxLcewwK9SMhYlo5WHpwR0x4NjA/edit?usp=sharing |
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UCLA Engineering Tech Forum, 2013 |
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2013-05-01 |
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#<DocumentCategory:0x007f418d101d98> |
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| 2013 |
5 |
2 |
Non-invasive Spoofing Attacks for Anti-lock Braking Systems |
This work exposes a largely unexplored vector of physical-layer attacks with demonstrated consequences in automobiles. By modifying the physical environment around analog sensors such as Antilock Braking Systems (ABS), we exploit weaknesses in wheel speed sensors so that a malicious attacker can inject arbitrary measurements to the ABS computer which in turn can cause life-threatening situations. In this paper, we describe the development of a prototype ABS spoofer to enable such attacks and the potential consequences of remaining vulnerable to these attacks. The class of sensors sensitive to these attacks depends on the physics of the sensors themselves. ABS relies on magnetic--based wheel speed sensors which are exposed to an external attacker from underneath the body of a vehicle. By placing a thin electromagnetic actuator near the ABS wheel speed sensors, we demonstrate one way in which an attacker can inject magnetic fields to both cancel the true measured signal and inject a malicious signal, thus spoofing the measured wheel speeds. The mounted attack is of a non-invasive nature, requiring no tampering with ABS hardware and making it harder for failure and/or intrusion detection mechanisms to detect the existence of such an attack. This development explores two types of attacks: a disruptive, naive attack aimed to corrupt the measured wheel speed by overwhelming the original signal and a more advanced spoofing attack, designed to inject a counter-signal such that the braking system mistakenly reports a specific velocity. We evaluate the proposed ABS spoofer module using industrial ABS sensors and wheel speed decoders, concluding by outlining the implementation and lifetime considerations of an ABS spoofer with real hardware. |
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Workshop on Cryptographic Hardware and Embedded Systems 2013 |
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55 |
72 |
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2013-08-01 |
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Santa Barbara |
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#<DocumentCategory:0x007f418cdf8c00> |
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| 2013 |
5 |
3 |
FireSense: Firewall-Based Occupancy Sensing |
As the field of occupancy detection grows, more and more sensors are being developed or repur-posed into occupancy detectors. Each of these new sensors brings with them new fees in mainte-nance and power. FireSense is a firewall-based sensor that seeks to repurpose existing infrastruc-tureto add sensing capabilities with little overhead. The sensor monitors network traffic over the firewall coverage space and reports network traffic statistics and events. Here, we show that the information can be used for occupancy detection, but that is by no means the limit to FireSense’s abilities. |
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https://www.dropbox.com/s/5qkih3ndla2ipg8/FireSense%20-%20Report.pdf |
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https://www.dropbox.com/s/wg6zqfv7finlvd8/FireSense%20-%20Slides.pdf |
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MS Project Report, UCLA CS Department |
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2013-05-01 |
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Los Angeles, CA |
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#<DocumentCategory:0x007f418cdb0360> |
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| 2012 |
2 |
2 |
CapMux: A Scalable Analog Front End for Low Power Compressed Sensing |
Although many real-world signals are
known to follow standard models, these signals are usually first
sampled, rather wastefully, at the Nyquist rate and only then
parametrized and compressed for efficient transport and analysis.
Compressed sensing (CS) is a new technique that promises to
directly produce a compressed version of a signal by projecting
it to a lower dimensional but information preserving domain
before the sampling process. Designing hardware to accomplish
this projection, however, has remained problematic and while
some hardware architectures do exist, they are either limited
in signal model or scale poorly for low power implementations.
In this paper, we design, implement and evaluate CapMux, a
scalable hardware architecture for a compressed sensing analog
front end. CapMux is low power and can handle arbitrary
sparse and compressible signals, i.e. it is universal. The key
idea behind CapMux’s scalability is time multiplexed access to
a single shared signal processing chain that projects the signal
onto a set of pseudo-random sparse binary basis functions. We
demonstrate the performance of a proof-of-concept 16-channel
CapMux implementation for signals sparse in the time, frequency
and wavelet domains. This circuit consumes 20µA on average
while providing over 30dB SNR recovery in most instances.
<hr>
<a href=http://nesl.ee.ucla.edu/fw/cs/HC_schem.pdf>Schematic</a>
<hr>
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http://nesl.ee.ucla.edu/fw/zainul/igcc12_capmux.pdf |
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Third International Green Computing Conference (IGCC'12) |
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2012-06-01 |
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San Jose, CA, USA |
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#<DocumentCategory:0x007f418d21e208> |
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| 2013 |
3 |
2 |
LabSense: An Extensible and Easily Configurable Energy Monitoring System |
This project involves sensing many different characteristics about a laboratory or room (such as ambient temperature and energy usage per electric socket). The different characteristics are obtained by a multitude of different sensors and devices deployed throughout the laboratory or room. The sensors in the system include temperature sensors, motion sensors, light sensors, door sensors, and several types of electricity meters. The data from these devices is sent to different data sinks. The data sinks provide a means of storage and visualization of the data. With this system, data scientists and engineers can simply worry about analyzing sensor data rather than worrying about retrieving the data with their own custom programs. The system has been developed to be easy to add new devices and data sinks so that users without LabSense’s hardware can still use the system effectively. |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWSlVKQWZNYTR3UHc/edit?usp=sharing |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWazNYNExWQXNnM0U/edit?usp=sharing |
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MS Project Report, UCLA Electrical Engineering Department |
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1 |
13 |
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2013-03-01 |
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Los Angeles, CA |
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#<DocumentCategory:0x007f418ceb2678> |
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| 2011 |
11 |
8 |
Balancing Behavioral Privacy and Information Utility in Sensory Data Flows |
Miniaturized smart sensors are increasingly being used to collect personal data which embed minute details of our everyday life. When shared, the data streams can easily be mined to draw a rich set of inferences regarding private behaviors and lifestyle patterns. Disclosure of some of these unintended inferences gives rise to the notion of behavioral privacy different from traditional identity privacy typically addressed in the literature. From the provider’s perspective, we summarize these privacy concerns into three basic questions: (i) Whom to share data with? (ii) How much data to share? and (iii) What data to share?
In this paper, we outline the architecture of SensorSafe as a software-based framework with support for three basic mechanisms to allow privacy-aware data sharing. First, it provides a library of routines accessible using a simple GUI for providers to define fine-grained, context-dependent access control. Second, it uses the trust network between consumers and providers to derive the optimal rate of information flow which would maintain both provider privacy and consumer utility. Finally, it introduces a compressive sensing based feature-sharing procedure to further control the amount of information release. We provide simulation results to illustrate the efficacy of each of these mechanisms. |
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http://nesl.ee.ucla.edu/fw/documents/journal/2012/chakraborty-pmc.pdf |
http://dx.doi.org/10.1016/j.pmcj.2012.03.002 |
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Pervasive and Mobile Computing |
8 |
3 |
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331 |
345 |
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2012-06-01 |
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Elsevier B.V. |
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#<DocumentCategory:0x007f418ce6ece8> |
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| 2011 |
11 |
9 |
Variability-Aware Tasking for Wireless Sensor Networks |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Wanner-UCLA-EE-ARR.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2011/Wanner-UCLA-EE-ARR.mov |
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UCLA EE Department Annual Research Review |
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2011-11-01 |
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| 2011 |
3 |
3 |
SewerSnort: A drifting sensor for in situ Wastewater Collection System gas monitoring |
Abstract
Biochemical reactions that occur in sewer pipes produce a considerable amount of hydrogen sulfide gas (H2S corrosive and poisonous), methane gas (CH4 explosive and a major climate change contributor), carbon dioxide (CO2 a major climate change contributor), and other volatile substances (collectively known as in-sewer gases). These toxic gases lead to contamination of natural environment, sewer pipe corrosion, costly operational expense, public safety issues, and legal disputes. In order to prevent biochemical reactions and to maintain healthy sewer pipes, frequent inspections are vital. Thus far, various schemes have been designed and developed to identify functional deficiencies in Wastewater Collection System (WCS). Nevertheless, the current inspection techniques are not for mapping the sewer gas concentration. In addition, because of such a harsh and hazardous environment a comprehensive sewer gases inspection has been prohibitively expensive.
In this paper we propose SewerSnort, a low-cost, unmanned, fully automated in-sewer gas monitoring system. A sensor float is introduced at the upstream station and drifts down sewer pipeline, while the sensor float collects gas measurements along with location information of sampling points. At the end of the journey, the gas measurements are retrieved from the float and used to generate gas concentration to be used for maintenance or repair. The key innovations of SewerSnort are the fully automated, end-to-end monitoring solution and the low energy self localizing strategy. From the implementation standpoint, the key enablers are the float mechanical design that fits the sewer constraints and the embedded sensor design that matches the float form factor and complies with the tight energy constraints. Experiments based on a dry land emulator demonstrate the feasibility of the SewerSnort concept, in particular, the localization technique and the embedded sensor design.
Keywords: Wastewater Collection System; Biochemical process; Electrochemical gas sensor; Received signal strength indicator based localization; Mobile sensing
Article Outline
1. Introduction
2. Background
2.1. Wastewater Collection System
2.2. In-sewer processes
2.3. Environmental and health impacts of sewer gas
3. SewerSnort system overview
3.1. System design requirements
3.2. SewerSnort: gas monitoring using drifting sensors
3.3. Feasibility of drifting sensors in sewers
4. SewerSnort system design
4.1. Hull design
4.2. Gas sensing unit
4.2.1. Electrochemical gas detection
4.2.2. Power concerns
4.2.3. Ratiometric signal conditioning
4.2.4. Implementing signal conditioning
4.3. Localization
4.3.1. RSSI-based SewerSnort localization
4.3.2. De-noising RSSI samples
4.3.3. Enhancement of location estimation assisted by flow velocity
4.4. Data acquisition
4.5. Emergency notification
4.6. Fault recovery
5. Experiments
5.1. SewerSnort gas sensor board evaluation
5.2. SewerSnort evaluation in a mobile environment
6. Related work
6.1. Advanced pipeline monitoring systems
6.2. Mobile robot localization in sewers
7. Conclusion and future work
Acknowledgements
References |
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http://www.sciencedirect.com/science/article/pii/S1570870511000382 |
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AdHoc Networks Journal |
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2011-03-01 |
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doi:10.1016/j.adhoc.2011.01.016 |
Elsevier |
true |
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| 2011 |
12 |
1 |
Considerations for the Design of an Epipelagic Biomimetic Electrostatic Imaging Element |
<h1>Video of the Conference Talk</h1>
<h5>If there is no video below this text, refresh the page in your browser or click <a href="http://vimeo.com/33067862">here</a>.</h5><br>
<iframe src="http://player.vimeo.com/video/33067862?title=0&byline=0&portrait=0" width="400" height="300" frameborder="1" webkitAllowFullScreen mozallowfullscreen allowFullScreen></iframe><p><a href="http://vimeo.com/33067862">Considerations for the Design of an Epipelagic Biomimetic Electrostatic Imaging Element</a> <br>from <a href="http://vimeo.com/user2516931">Jonathan Friedman</a> on <a href="http://vimeo.com">Vimeo</a>.</p>
<h1>Paper Abstract</h1>
We discuss the development and design of a Biomimetic
Electrostatic Imaging (BEI) element for use in a future multi-channel imaging instrument. Inspiration for electrostatic
sensing is provided by the diverse species of sh that use
passive and induced electric elds for hunting, defense, localization, and communication. Designing an electrostatic
sensor is not without its challenges. Hardware lter and
ampli er design are analyzed since the high impedance signals require high gain and steps must be taken to minimize
noise, maximizing signal to noise ratio. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/friedman-wuwnet.pdf |
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http://nesl.ee.ucla.edu/fw/documents/conference/2011/friedman-wuwnet-slides.pdf |
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http://vimeo.com/33067862 |
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The Sixth ACM International Workshop on UnderWater Networks (WUWNet) |
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5 |
2011-12-01 |
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Seattle, Washington |
ACM |
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#<DocumentCategory:0x007f418d51d1c0> |
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| 2012 |
11 |
1 |
Probabilistic Computation for Information Security |
Probabilistic computation is a convenient means of mechanically reasoning about a variety of information security problems. At its core, information security concerns itself with measuring or limiting the knowledge an adversary might attain from interacting with a protected system. Probabilistic
inference lets one compute this knowledge explicitly as long as the interaction can be described as a
program in a suitable probabilistic language that supports conditioning. Security concerns, however,
require soundness guarantees on probabilistic inference which are generally not present in machine
learning applications. We summarize some recent work on probabilistic computing for information
security and highlight challenging aspects that still need to be addressed. |
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http://nesl.ee.ucla.edu/fw/kasturi/prob_info_sec.pdf |
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NIPS Workshop on Probabilistic Programming |
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3 |
2012-12-01 |
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Lake Tahoe, CA |
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#<DocumentCategory:0x007f418d52a910> |
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| 2012 |
8 |
1 |
Content Dissemination Protocols in Hybrid Wireless Networks |
Wireless hybrid networks have become quite popular with the evolution of several devices with multiple networking interfaces. Each of these interfaces (and the associated networks) have significantly different characteristics, hence it is important to understand how best to utilize and operate in the presence of multiple networks. Smartphones are a popular example of devices with multiple networking interfaces, e.g. WiFi and cellular. As these devices become popular with soldiers in battlefields for communications, an important question is to address the issue of how best to utilize the multiple networks while minimizing delay in content delivery and maximizing the utility of these networks. In this paper, we explore the tradeoffs between the use of cellular and WiFi interfaces in the context of a network of mobile nodes (patrolling a specified area). We consider a network model in which nodes use WiFi in ad-hoc mode (forming a MANET) and exchange data when they come in contact with each other, whereas the cellular link provides direct connectivity. We address the problem of disseminating content to a group of mobile nodes (possibly the entire network) in the presence of a cellular and ad-hoc WiFi networks. Cellular links are bandwidth-constrained and expensive, but provide low delay for data dissemination. On the other hand, ad-hoc WiFi networks offer higher bandwidth and are inexpensive, but could incur high data delivery delays due to intermittent node connectivity. We develop a protocol for achieving this low delay and low cost data delivery that employs machine learning techniques in a novel manner and evaluate the efficacy of this protocol on a dataset with 100 mobile nodes (patrolling a specified area). We show through extensive simulations based on real-world mobility patterns of the 100 nodes that the bandwidth consumed on the cellular link can be reduced by about 50% on an average while not increasing the delay incurred (in data delivery) significantly. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/choi-acita.pdf |
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https://docs.google.com/file/d/0B70b6Z49qQH0NkNPX19nMWZoS3c/edit?usp=sharing |
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Annual Conference of ITA |
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2012-09-01 |
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| 2012 |
2 |
1 |
Low-cost Estimation of Sub-system Power |
Real-time, fine-grained power consumption information enables energy optimization and adaptation for both operating system (OS) and applications. Due to the high cost associated with dedicated power sensors, however, most computers do not have the ability to measure disaggregated power consumption at a component or subsystem level. We present DiPART (Disaggregated Power Analysis in Real Time), a tool to estimate subsystem power consumption based on performance (event) counters and a single, system-wide power sensor. With only one power sensor for overall system power consumption, DiPART is able to self-adapt to variations in subsystem power consumption present across nominally identical hardware. We validate the approach using a cluster of Intel Atom-based nodes that has been instrumented for subsystem power measurements (CPU, RAM and disk). DiPART was tested across nodes in the cluster using varied benchmarks, resulting in a 40% reduction in estimation error when compared to a static model. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/Sun_IGCC_2012.pdf |
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http://nesl.ee.ucla.edu/fw/documents/slides/2012/IGCC2012.pdf |
http://nesl.ee.ucla.edu/fw/documents/slides/2012/IGCC2012.key |
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Proceedings of the Third International Green Computing Conference (IGCC'12) |
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2012-06-01 |
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San Jose, CA, USA |
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#<DocumentCategory:0x007f418d6ebfb0> |
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| 2013 |
3 |
1 |
Magnetic Field Feature Analysis of Smartphone Application Activities Using Android MI Sensors |
In this project, the magnetic field data of three axes are read by the magnetometer in an Android Smartphone and are recorded by an application then processed through MATLAB. Various denoising techniques and frequency domain analysis is implemented and two sets of experiment are designed by varying the direction, the phone activity, and the distance.
The first experiment is done in order to analyze the magnetic field feature generated by another smartphone, whereas the second experiment is to monitor the change of the magnetic field due to different activities running on the same phone. WiFi transmitting and music-playing activities are chosen for the test, and different characteristics of magnetic field features are discovered respectively. |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWbXgzYzgwSzNwYzg/edit?usp=sharing |
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https://docs.google.com/file/d/0Bw3RgUXZhsrWNjFUM3VGdnJ4ZHc/edit?usp=sharing |
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MS Project Report, UCLA Electrical Engineering Department |
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1 |
23 |
23 |
2013-03-01 |
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Los Angeles, CA |
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#<DocumentCategory:0x007f418d8b5e90> |
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| 2012 |
3 |
1 |
Variability-Aware Embedded Sensor Tasking |
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http://nesl.ee.ucla.edu/fw/documents/posters/2012/wanner-techforum.pdf |
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UCLA Tech Forum |
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2012-03-01 |
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#<DocumentCategory:0x007f418d50ca50> |
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| 2012 |
3 |
2 |
An Obfuscation Framework For Controlling Value Of Information During Sharing |
Sensory information is characterized by its inherent quality
and context-specific value. It is thus natural that the information
provider would want to exercise control over the information
shared based on her perception of the risk of possible
misuse due to sharing and also depending on the consumer
requirements. To attain this utility vs. risk trade-off, information
is subjected to varying but deliberate quality modifying
transformations which we term as obfuscation. In this
paper, treating privacy as the primary motivation for information
control, we highlight initial considerations of using
feature sharing as an obfuscation mechanism to control the
inferences possible from shared sensory data. We provide results
from an activity tracking scenario to illustrate the use of
feature selection in identifying the various trade-off points. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2012/ssp2012_submitted.pdf |
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Statistical Signal Processing 2012 |
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2012-03-01 |
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#<DocumentCategory:0x007f418d23dc70> |
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| 2012 |
4 |
1 |
Applied At-Depth In-Ocean Differential Electrostatics -- An Experimental Study |
Nocturnal oceanic animals and those that live at depth can- not rely upon optical notions of vision to navigate, hunt, or avoid preda- tors. Instead, many rely upon an electroreceptive capability achieved through a dense grid of electric field (Voltage) sensors arrayed along both sides of the body and concentrated around the head. Our prior works have detailed the creation of an engineered sensor which mirrors this biological system and demonstrated its ability to “visualize” targets with different conductivities from the background ocean environment – a process we entitle Biomimetic Electrostatic Imaging (BEI). Our prior imaging studies were performed in the laboratory in a well controlled ocean-simulant tank.
This work chronicles our effort to validate beyond the laboratory. To better evaluate the potential capabilities of BEI in the actual ocean, an expedition was undertaken to the Pacific Ocean to a site in the coastal city of Marina Del Rey, California. A six and half hour study was conducted by a cantilevered purpose-built robotic gantry system (figure 1), which collected over 10,000 data points at 635 micron-square resolution, resulting in the highest resolution study ever reported.
A mathematical model is derived from first principals and used to corroborate the findings. Several smaller studies are also included to present data relevant to design optimization. The improved BEI system described within increased detection range by 97% and range-power efficiency by as much as 150% over our previous report without a corresponding increase in the false positive rate. We also report sensing and excitation ranges 7× their respective electrode separation distances – the furthest ever reported. |
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2012-05-01 |
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#<DocumentCategory:0x007f418d786fb0> |
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| 2012 |
5 |
1 |
Localization in Cognitive Radio Systems In The Presence of Spatially Obfuscated Data |
Localizing primary users using observations collected from secondary users sensing the spectrum is a key aspect for improved operations in cognitive radio networks. However, malicious secondary users may obfuscate their location reports causing disruption in the network operation. In this paper we take a first step towards addressing the challenging problem of primary user localization in the presence of secondary users of varying trust that may randomly obfuscate their reports while maintaining plausibility of their content. Using localization reports as evidences in support of (or against) hypotheses about user locations, we develop the foundations of an evidential reasoning-based approach that uses subjective logic for information fusion and inferencing for localization in the presence of incomplete and conflicting knowledge. To do so, we exploit our recent extensions of subjective logic that accommodate the spatial relationships that naturally exists between location reports. After highlighting our spatial extensions, we apply them in building an inferencing algorithm for primary user localization. Through extensive simulations, we analyze its performance and the effect of various design parameters, showing a 90\% accuracy in localization. Finally, we compare it with other localization techniques via simulations. |
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http://nesl.ee.ucla.edu/fw/documents/reports/2012/supriyo_acita_report.pdf |
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2012-05-01 |
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#<DocumentCategory:0x007f418cda1c70> |
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| 2012 |
4 |
2 |
Context-Aware Sensor Data Dissemination for Mobile Users in Remote Areas |
Many mobile sensing applications consider users reporting and accessing sensing data through the Internet. However, WiFi and 3G connectivities are not always available in remote areas. Existing data dissemination schemes for oppor- tunistic networks are not sufficient for sensing applications as sensing context has not been explored. In this work, we present a novel context-aware sensing data dissemination framework for mobile users in a remote sensing field. It maximizes information utility by considering such sensing context as sensing type, locality, time-to-live, mobility and user interests. Different from existing works, the mobile users not only collect sensing data, but also upload data to sensors for information sharing. We develop a context-aware deployment algorithm and a hybrid data exchange mechanism for generic sensors and mobile users. We evaluate our solution by both analysis and simulations, and show that it can provide high information utility for mobile users at low communication overhead. |
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The 31st Annual IEEE International Conference on Computer Communications: Mini-Conference |
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2993 |
2997 |
5 |
2012-04-01 |
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Orlando, FL |
IEEE |
false |
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#<DocumentCategory:0x007f418cf35578> |
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| 2012 |
4 |
3 |
Trust and Obfuscation Principles for Quality of Information in Emerging Pervasive Environments |
The emergence of large scale, distributed, sensor- enabled, machine-to-machine pervasive applications necessitates engaging with providers of information on demand to collect the information, of varying quality levels, to be used to infer about the state of the world and decide actions in response. In these highly fluid operational environments, involving information providers and consumers of various degrees of trust and intentions, obfus- cation of information is used to protect providers from misuses of the information they share, while still providing benefits to their information consumers. In this paper, we develop the initial principles for relating to trust and obfuscation within the context of this emerging breed of applications. We start by extending the definitions of trust and obfuscation into this emerging application space. We, then, highlight their role as we move from tightly- coupled to loosely-coupled sensory-inference systems. Finally, we present the interplay between trust and obfuscation as well as the implications for reasoning under obfuscation. |
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The 4th International Workshop on Information Quality |
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44 |
49 |
6 |
2012-03-01 |
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Lugano, Switzerland |
IEEE |
false |
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#<DocumentCategory:0x007f418d2a3098> |
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| 2012 |
4 |
4 |
Trust and Obfuscation |
In modern coalition operations, decision makers must be capable of obtaining and fusing data from diverse sources. The reliability of these sources can vary, and, in order to protect their interests, the data they provide can be obfuscated. The trustworthiness of fused data depends on both the reliability of these sources and their obfuscation strategy. Information consumers must determine how to evaluate trust in the presence of obfuscation, while information providers must determine the appropriate level of obfuscation in order to ensure both that they remain trusted, and do not reveal any private information. In this paper, through a coalition scenario, we discuss and formalise trust and obfuscation in these contexts and the complex relationships between them. |
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2012 SPIE Defense, Security + Sensing: Ground/Air Multisensor Interoperability, Integration, and Networking for Persistent ISR III |
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11 |
2012-04-01 |
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false |
true |
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#<DocumentCategory:0x007f418d544fe0> |
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| 2012 |
6 |
1 |
Low-cost Appliance State Sensing for Energy Disaggregation |
Fine-grained per appliance electrical energy consumption data is crucial to electrical energy conservation. However, energy meters are installed at few central points in buildings, providing only aggregated energy consumption data. Therefore, people are seeking ways to get disaggregated energy information. A key issue and most challenging problem in energy disaggregation is to know the power state of each appliance. We design a sensing system that can reliably keep track of the binary (on-off) states of appliances.
In our system, the sensors are designed to be deployed at each appliance. However, we are able to minimize the hardware requirements so that the sensors are inherently low-cost. The whole system is totally affordable for large scale deployment. The evaluation shows that, despite the simplicity of hardware, the system can keep track of the power state of tens of appliances at 99.5% precision and recall with a single base station. We also propose an energy disaggregation approach, based on the information our sensor network provides combined with central power meter readings. |
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http://nesl.ee.ucla.edu/pw/NESL/theses/2012_06_ms_TW.pdf |
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M.S. Thesis, UCLA EE Department |
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56 |
2012-06-01 |
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Los Angeles |
EE Department, UCLA |
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true |
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#<DocumentCategory:0x007f418d5a7c30> |
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| 2012 |
6 |
2 |
LabSense: Energy Monitoring in the Browser |
This project involves sensing many different characteristics about a lab (i.e. ambient temperature, electricity, water, occupancy) and making the data available in a user intuitive web interface. |
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http://nesl.ee.ucla.edu/~neslfw/documents/reports/2012/2012_06_JT_labsense_ee209as_report.pdf |
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http://nesl.ee.ucla.edu/~neslfw/documents/slides/2012/2012_06_JT_labsense_ee209as_slides.pdf |
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UCLA EE Department, EE209AS Course Project |
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5 |
2012-06-01 |
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Los Angeles |
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true |
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#<DocumentCategory:0x007f418d3d6758> |
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| 2012 |
7 |
1 |
Model-based Risk Analysis for Data Stream Queries |
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http://nesl.ee.ucla.edu/fw/kasturi/dbn_risk.pdf |
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2012-07-01 |
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true |
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#<DocumentCategory:0x007f418d259358> |
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| 2012 |
7 |
2 |
DoubleDip: Leveraging Thermoelectric Harvesting for Low Power Monitoring of Sporadic Water Use |
We present DoubleDip, a low power monitoring system that harvests energy from the very phenomenon it senses – water flow in pipes. One of the remaining issues with wireless water monitoring in residences and offices is that current solutions require installing sensor nodes with access to electrical wiring or replacing batteries frequently. DoubleDip (DD) significantly extends the lifetime of vibration based non-intrusive water flow sensors by harvesting thermal energy from hot pipes wherever accessible. DoubleDip requires less than an inch of exposed metal pipe to attach a coupler for gathering sufficient energy to power itself, in some cases, into perpetuity. We observe that water use in homes and offices is incredibly sporadic, making continuous monitoring both impractical and wasteful. Instead, DD puts a thermoelectric harvester into double duty. It uses thermal gradients not only for gathering energy but also for extremely low power (< 1μA) wakeup. In this paper, we elaborate the DoubleDip design and demonstrate that thermoelectric wakeup is essential for longevity and accuracy. Since DD wakes up from its low power state only when there is a water flow event, it replenishes the energy it uses in sensing and transmitting data by the energy it harvests from the water flow. While DD nodes installed on cold water pipes harvest far less than those installed on hot water pipes, our pilot deployment over two weeks in four locations suggests that thermoelectric wake up is only slightly worse in latency for cold water monitoring and there is sufficient energy harvested from the hot water that it can be shared to extend the lifetime of nearby cold water nodes too. |
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Proceedings of the 10th ACM Conference on Embedded Networked Sensor Systems (SenSys 2012) |
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2012-11-01 |
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Toronto, Canada |
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#<DocumentCategory:0x007f418d4d42e0> |
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| 2012 |
3 |
3 |
Fusion of Classifiers: A Subjective Logic Perspective |
This work investigates decision level fusion by ex- tending the framework of subjective logic to account for hidden observations. Bayes rule might suggest that decision level fusion is simply calculated as the normalized product of the class likelihoods of the various classifiers. However, this product rule suffers from a veto issue. The problem with the classical Bayes formulation is that it does not account for uncertainties inherent in the likelihoods exclaimed by the classifiers. This paper uses subjective logic as a rigorous framework to incorporate uncertainty. First, a class appearance model is introduced that roughly accounts for the disparity between training and testing conditions. Then, the subjective logic framework is expanded to account for the fact that class appearances are not directly observed. Rather, a classifier only returns the likelihood for the class appearance. Finally, the paper uses simulations to com- pare the new subjective logic framework to traditional classifier fusion methods in terms of classification performance and the ability to estimate the parameters of the class appearance model. |
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https://www.usukita.org/sites/default/files/sl_class_fusion_v5.pdf |
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Proceedings of the 2012 Aerospace Conference |
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1 |
13 |
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2012-03-01 |
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Big Sky, MT, USA |
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#<DocumentCategory:0x007f418d7a6e28> |
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| 2012 |
8 |
2 |
Override: A Mobile Privacy Framework for Context-Driven Perturbation and Synthesis of Sensor Data Streams |
Smart phones with increased computation and sensing capabilities have spurred the growth of a new generation of context-aware apps. These apps often make judicious use of the readily-available sensor data to infer users' personal context but most do provide some useful service in return. However, sharing sensor data with apps leaves room for abuse; a malicious app can extract information that is sensitive and considered private by the user. Current approaches to mitigate the privacy concerns rely on simple user-specified policies that consist of static rules and are limited to binary access control. These rules are often conservative and lead to a sharp decline in application utility. In this paper we aim to address the above challenge of balancing user privacy and application utility. To this end, we present OVERRIDE: a mobile privacy framework that empowers users to control the sensor data being delivered to apps. It does so by providing apps access to perturbed or even synthetic sensor data streams. We discuss the key architectural elements of OVERRIDE and its prototype implementation on the Android platform. We highlight its ability to give users increased transparency and control over shared sensor data, and then discuss its other secondary benefits. |
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http://nesl.ee.ucla.edu/fw/kasturi/override_privacy.pdf |
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PhoneSense (SenSys Workshop) |
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2012-11-01 |
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#<DocumentCategory:0x007f418d02e060> |
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| 2012 |
8 |
3 |
Model-Based Context Privacy for Personal Data Streams |
Smart phones with increased computation and sensing ca- pabilities have enabled the growth of a new generation of applications which are organic and designed to react de- pending on the user contexts. These contexts typically de- fine the personal, social, work and urban spaces of an in- dividual and are derived from the underlying sensor mea- surements. The shared context streams therefore embed in them information, which when stitched together can reveal behavioral patterns and possible sensitive inferences, raising serious privacy concerns. In this paper, we propose a model based technique to capture the relationship between these contexts, and better understand the privacy implications of sharing them. We further demonstrate that by using a gen- erative model of the context streams we can simultaneously meet the utility objectives of the context-aware applications while maintaining individual privacy. We present our cur- rent implementation which uses offline model learning with online inferencing performed on the smart phone. Prelimi- nary results are presented to provide proof-of-concept of our proposed technique. |
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19th ACM Conference on Computer and Communications Security |
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2012-08-01 |
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#<DocumentCategory:0x007f418cd31330> |
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| 2012 |
4 |
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MiDebug: microcontroller integrated development and debugging environment |
We present MiDebug, a web-based Integrated Development Environment (IDE) for embedded system programming with in-browser debugging capabilities. This web application greatly reduces the time and effort required for rapid prototyping of microcontroller based devices. |
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http://delivery.acm.org/10.1145/2190000/2185714/p133-shen.pdf?ip=128.97.92.37&acc=ACTIVE%20SERVICE&CFID=147640448&CFTOKEN=26638944&__acm__=1346117466_f5d98e523dfc9b185cae417fabc32b9a |
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IPSN '12, the 11th international conference on Information Processing in Sensor Networks |
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133 |
134 |
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2012-04-01 |
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Beijing, China |
ACM |
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#<DocumentCategory:0x007f418cbfec10> |
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| 2012 |
9 |
1 |
Variability-Aware Task Scheduling for Embedded Sensors |
As manufacturing feature geometries continue to shrink, component variability plays an increasingly large role in determining a system’s power consumption. Specifically, prior work has illustrated that variations in sleep power caused by manufacturer variation can have a very large effect on system lifetime and consequently application quality for low power devices.
We provide an extension to the FreeRTOS operating system that tunes task activations and duty cycling rates in order order to maximize total system quality in the face of an energy budget. This is accomplished by introducing task knobs --- variables defined by the application developer that affect either the frequency or duration of a task. The scheduler determines values for any given knob according to a reward function, task priorities, and the individual power consumption characteristics of the hardware executing the tasks. Accounting for hardware variability requires accurate instance models. We evaluate the potential for learning various models online---per-instance sleep power vs. temperature, deployment temperature profiles, knob value vs. duty cycle ratio, etc. We evaluate the proposed variability-aware RTOS using the QEMU simulation suite with added variability extensions.
In the proposed variability-aware task scheduler, we consider a general case where utility is non- homogeneous across tasks and is defined by the utility function u(d), d being the duty cycle in [0,1]. Usually, the utility of a task will increase to some threshold where an increase in d no longer yields an appreciable increase in u.We define each task as an application Ai={Fi,ui(d),ki,kmiin,kmiax,pi}, where Fi is the application handle, ui(d) is the utility function, k is a user-provided knob that presumably will have a proportionate increase in the quality of the task, kmin and kmax are the minimum and maximum acceptable knob values for Ai, and pi in R+ is the pseudo-priority (read utility scalar) of application Ai. Upon task creation, the OS will enter a learning period wherein it will perturb the task knob and measure the corresponding execution time. This yields a mapping per task from knob value to duty cycle ratio. Once this mapping has converged for all tasks, the OS arrives at and assigns an optimal task knob for all active tasks. This is done by successive incrementation of duty cycle per-task where priority is given to tasks with the highest marginal utility determined from ui(d) and the mapping k -> d. This assumes that utility is monotonically non-decreasing, and rather than rely on the user to provide some function of quality per task we transfer this burden to the OS, where ui(d) is modeled as a logistic sigmoid function reachingmaximumvalueatkmiax.
The resulting OS has almost negligible code overhead as seen by the user, while intelligently achieving a lifetime goal within the bounds of reason as specified by the user and each specific application. This variability-aware OS is implemented as an extension to the FreeRTOS kernel—a preemptable embedded RTOS. The extension comprises 830 LoC, giving a 7% code overhead and 52.7% overhead in ROM from 10.7 kB to 16.4 kB. Memory per task is increased from 64 bytes to 86 bytesa 34% increase. Variability-tasks are created through a new API, taking as an input the user-provided knob address. |
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OSDI '12 |
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2012-09-01 |
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| 2012 |
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Mobile Health - Revolutionizing Health via Transdisciplinary Research |
Mobile health (mHealth) represents a unique confluence of mobile technology and health. It seeks to improve health and wellbeing in ways previously unimaginable, by continuous monitoring of health status, rapid diagnosis of health conditions, and delivery of just-in-time interventions and personalized prevention programs, all in the natural mobile environment of individuals. mHealth promises to revolutionize health research, practice, delivery, and public policy, and opens up numerous opportunities for trans-disciplinary research in computing and health disciplines. This article describes current and future research directions in mobile health systems, discusses challenges in establishing safety, efficacy, privacy and security in mobile health, and reviews recent regulatory efforts. |
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IEEE Computer |
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2013-01-01 |
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IEEE |
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How to be an Entrepredemic |
<!-- ACM DL Article: How to be an "entrepredemic" -->
<div class="acmdlitem" id="item2173644"><img src="http://dl.acm.org/images/oa.gif" width="25" height="25" border="0" alt="ACM DL Author-ize service" style="vertical-align:middle"/><a href="http://dl.acm.org/authorize?6776922" title="How to be an "entrepredemic"">How to be an "entrepredemic"</a><div style="margin-left:25px"><a href="http://dl.acm.org/author_page.cfm?id=81342494853" >Jonathan Friedman</a><br />XRDS: Crossroads, The ACM Magazine for Students - The Role of Academia in the Startup World, 2012</div></div>
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<p style="width:500px; text-align:justify; margin-left:20px;"> Dear future colleagues, when it comes to your job, you have a choice to make, but it’s not the one you think. Many of my former students and interns once thought as you do— I can either be an academic or an entrepreneur. In practice, it’s a false choice. Academic research is a highly entrepreneurial enterprise where big intellectual risks are taken to reach even greater societal benefits. Startups work with financial benefits, but the actual mechanics are largely identical: You rise or fall on the combined strength of your ideas and your resolve to realize them... </p> |
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http://nesl.ee.ucla.edu/fw/documents/magazine/2012/2012-friedman-XRDS-12-4-p8.pdf |
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XRDS: Crossroads, The ACM Magazine for Students - The Role of Academia in the Startup World |
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SensorAct: A Privacy and Security Aware Federated Middleware for Building Management |
The archaic centralized software systems, currently used to manage buildings, make it hard to incorporate advances in sensing technology and user-level applications, and present hurdles for experimental validation of open research in build- ing information technology. Motivated by this, we — a transnational collaboration of researchers engaged in development and deployment of technologies for sustainable buildings — have developed SensorAct, an open-source federated middleware incorporating features targeting three specific requirements: (i) Accommodating a richer ecosystem of sensors, actuators, and higher level third-party applications (ii) Participatory engagement of stakeholders other than the facilities department, such as occupants, in setting policies for management of sensor data and control of electrical systems, without compromising on the overall privacy and safety, and (iii) Flexible interfacing and information ex- change with systems external to a building, such as communication networks, transportation system, electrical grid, and other buildings, for better management, by exploiting the teleconnections that exist across them. SensorAct is de- signed to scale from small homes to network of buildings, making it suitable not only for production use but to also seed a global-scale network of building testbeds with appropriately constrained and policed access. This paper describes SensorAct’s architecture, current implementation, and preliminary performance results. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/pandarasamy-buildsys.pdf |
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The 4th ACM Workshop On Embedded Systems For Energy-Efficiency In Buildings |
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2012-11-01 |
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Toronto, Canada |
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| 2012 |
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3 |
Low-cost Appliance State Sensing for Energy Disaggregation |
Reliable detection of appliance state change is a barrier to the scalability of Non Intrusive Load Monitoring (NILM) beyond a small number of sufficiently distinct and large loads. We advocate a hybrid approach where a NILM algorithm is assisted by ultra-low-cost outlet-level sensors optimized for detecting appliance state change and communicating the event on a best-effort basis to a central entity for opportunistic fusion with the state change detection mechanism within NILM. In support of such an approach we present the implementation of an appliance power state sensor which achieves low cost via design choices such as a transmit-only radio. We also present results from a study where the sensors tracked power states of tens of appliances with high accuracy. |
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https://www.dropbox.com/s/7gbegu7x6tstmib/1569654935.pdf |
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https://www.dropbox.com/s/4z59wg7arwz4iy0/poster-tianji.pdf |
https://www.dropbox.com/s/xxn48nc1al5pmat/poster-tianji.key |
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Proceedings of the 4th ACM Workshop On Embedded Systems For Energy-Efficiency In Buildings |
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2012-11-01 |
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Toronto, Canada |
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| 2012 |
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Underdesigned and opportunistic computing in presence of hardware variability |
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IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems |
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2012-11-01 |
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IEEE |
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A Framework for Context-Aware Privacy of Sensor Data on Mobile Systems |
We study the competing goals of utility and privacy as they arise when a user shares personal sensor data with apps on a smartphone. On the one hand, there can be value to the user for sharing data in the form of various personalized services and recommendations; on the other hand, there is the risk of revealing behaviors to the app producers that the user would like to keep private. The current approaches to privacy, usually defined in multi-user settings, rely on anonymization to prevent such sensitive behaviors from being traced back to the user—a strategy which does not apply if user identity is already known, as is the case here.
Instead of protecting identity, we focus on the more general problem of choosing what data to share, in such a way that certain kinds of inferences—i.e., those indicating the user’s sensitive behavior—cannot be drawn. The use of inference functions allows us to establish a terminology to unify prior notions of privacy as special cases of this more general problem. We identify several information dis- closure regimes, each corresponding to a specific privacy- utility tradeoff, as well as privacy mechanisms designed to realize these tradeoff points. Finally, we propose ipShield as a privacy-aware framework which uses current user con- text together with a model of user behavior to quantify an adversary’s knowledge regarding a sensitive inference, and obfuscate data accordingly before sharing. We conclude by describing initial work towards realizing this framework. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2013/supriyo_hotmobile.pdf |
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ACM HotMobile 2013 |
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2013-02-01 |
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| 2012 |
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Realtime in-Ocean Submerged Collision Avoidance via Biomimetic Electrostatic Imaging |
This paper explores a technique to exploit Biomimetic Electrostatic Imaging (BEI) for the purposes of short-range high-speed detection and tracking of submerged obstacles based on their conductivity deviation from the background ocean environment. BEI uses conductivity and Coulomb’s law rather than electromagnetic or acoustic (SONAR) principles to provide more rapid imaging at substantially reduced out- put powers making the technique perfect for Uncrewed Underwater Vehicles (UUV) seeking to align for docking, avoid obstacles while traversing, perform relative station keeping (formation management), or track/follow a target object. It is demonstrated to work in real-time against the type of short-range targets that pose a collision threat. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2012/2012_11_WUWNet_JF.pdf |
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Proceedings of the International Conference on UnderWater Networks and Systems (WUWNet) |
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2012-11-01 |
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| 2013 |
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VarEMU: An Emulation Testbed for Variability-Aware Software |
Modern integrated circuits, fabricated in nanometer technologies, suffer from significant power/performance variation across-chip, chip-to-chip and over time due to aging and ambient fluctuations. Furthermore, several existing and emerging reliability loss mechanisms have caused increased transient, intermittent and permanent failure rates. While this variability has been typically addressed by process, device and circuit designers, there has been a recent push towards sensing and adapting to variability in the various layers of software. Current hardware platforms, however, typically lack variability sensing capabilities. Even if sensing capabilities were available, evaluating variability-aware software techniques across a significant number of hardware samples would prove exceedingly costly and time consuming.
We introduce VarEMU, an extension to the QEMU virtual machine monitor that serves as a framework for the evaluation of variability-aware software techniques. VarEMU provides users with the means to emulate variations in power consumption and in fault characteristics and to sense and adapt to these variations in software. Through the use (and dynamic change) of parameters in a power model, users can create virtual machines that feature both static and dynamic variations in power consumption. Faults may be injected before or after, or completely replace the execution of any instruction. Power consumption and susceptibility to faults are also subject to dynamic change according to an aging model. A software stack for VarEMU features precise control over faults and provides virtual energy monitors to the operating system and processes. This allows users to precisely quantify and evaluate the effects of variations on individual applications. We show how VarEMU tracks energy consumption according to variation-aware power and aging models and give examples of how it may be used to quantify how faults in instruction execution affect applications. |
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Proceedings of the International Conference on Hardware/Software Codesign and System Synthesis (CODES+ISSS) |
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2013-09-01 |
2013-10-01 |
Montreal, Canada |
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Reasoning Under Uncertainty: Variations of Subjective Logic Deduction |
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http://nesl.ee.ucla.edu/fw/documents/conference/2013/kaplan-fusion-2013.pdf |
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Proceedings of the 16th International Conference on Information Fusion |
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2013-07-01 |
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Istanbul, Turkey |
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| 2013 |
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Protecting Data Against Unwanted Inferences |
We study the competing goals of utility and privacy as they arise when a provider delegates the processing of its personal information to a recipient who is better able to handle this data. We formulate our goals in terms of the inferences which can be drawn using the shared data. A whitelist describes the inferences that are desirable, i.e., providing utility. A blacklist describes the unwanted inferences which the provider wants to keep private. We formally define utility and privacy parameters using elementary information-theoretic notions and derive a bound on the region spanned by these parameters. We provide constructive schemes for achieving certain boundary points of this region. Finally, we improve the region by sharing data over aggregated time slots. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2013/supriyo_ITW.pdf |
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Proceedings of the 2013 Information Theory Workshop |
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2013-09-01 |
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Seville, Spain |
IEEE |
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| 2013 |
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5 |
On the Quality and Value of Information in Sensor Networks |
The increasing use of sensor-derived information from planned, ad-hoc, and/or opportunistically deployed sensor networks provides enhanced visibility to everyday activities and processes, enabling fast-paced data- to-decision in personal, social, civilian, military, and business contexts. The value that information brings to this visibility and ensuing decisions depends on the quality characteristics of the information gathered. In this article, we highlight, refine, and extend upon our past work in the areas of quality and value of information (QoI and VoI) for sensor networks. Specifically, we present and elaborate on our two-layer QoI/VoI definition, where the former relates to context-independent aspects and the latter to context-dependent aspects of an information product. Then, we refine our taxonomy of pertinent QoI and VoI attributes anchored around a simple ontological relationship between the two. Finally, we introduce a framework for scoring and ranking information products based on their VoI attributes using the analytic hierarchy multicriteria decision process, illustrated via a simple example. |
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ACM Transactions on Sensor Networks |
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| 2013 |
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Energy Management Based On Charging Behavior Prediction |
As mobile applications transition into providing richer content and supporting more use-cases, it has become increasingly apparent that smart-phones are constrained by battery life. Industry has put great effort into energy-aware hardware platforms, but little attention has been given to designing energy efficiency around user charging behavior. If smart-phones were to become capable of accurately predicting the time and duration of charging events of specific users, task scheduling could be more intelligently catered towards the user. Our project examines whether machine learning can be reliably implemented on smart-phones to infer aspects of charging behavior, as well as the appropriate classification schemes required to accurately predict future charging events.
By implementing SystemSens, we have developed an alternative model to offload model training to a server and provide user-specific models to the phone. The new application, Tree-Diagram, manages classification on the client-side and keeps track of prediction accuracy. Many server side scripts also do additional processing that produce attribute-relation files that we can analyze externally.
Using the machine learning suite Weka[1], we found that the “Random Tree” classifier yielded the most accurate results initially. Later analysis showed that classifier strength varies across different users and over time as the datasets grow. We found that the prediction capability was strongest when using the attributes of time, battery level, charging status, and statistics of the most recent charging session. Our application utilized our classifier and predicted the time until the user’s next charge accurately, and without high-resource use. |
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https://dl.dropboxusercontent.com/u/35098178/Prashanth_paper.pdf |
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WHI Summer Intern Final Report |
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2013-08-01 |
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Los Angeles, CA |
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| 2013 |
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Energy Management Based on Charging Behavior Prediction |
As mobile device applications continue to include richer content, the need for maximizing power efficiency on the devices increases. While a great deal of effort is put into designing more energy efficient hardware platforms, not much attention has been given to individual users’ charging behaviors.
Assuming that every user will charge his/her device differently, we can potentially increase battery life by dynamically scheduling tasks to take place when their impact on the battery is minimal (such as during an overnight charge). In order to allow this optimization, we made use of machine learning algorithms to predict charging behavior.
We gathered data using SystemSens, an Android program developed by Dr. Hossein Falaki. Through testing and cross-validation in the machine learning suite Weka, we found that the “RandomTree” classifier yielded the most accurate results in tandem with our feature selection. We used the raw reported values of battery status, battery level, and time, as well as extracted features for the last charging time, last charging level, and duration of last charge. These proved to be the most important features for predicting the time before the next expected charge, giving us approximately 90% accuracy on our training sets.
After finalizing our feature and classifier selection, we developed an architecture in which the phone locally polls data, uploads it to a server for training a model, and then receives that model and runs it on the phone, providing a platform for accurately predicting individual charging behavior. |
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https://dl.dropboxusercontent.com/u/35098178/MikhaelsPaper.pdf |
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WHI Summer Intern Final Report |
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| 2013 |
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Exploiting Processor Heterogeneity For Energy Efficient Context Inference On Mobile Phones |
In recent years we have seen the emergence of context-aware mobile sensing apps which employ machine learning algorithms on real-time sensor data to infer user behaviors and contexts. These apps are typically optimized for power and performance on the app processors of mobile platforms. However, modern mobile platforms are sophisticated system on chips (SoCs) where the main app processors are complemented by multiple co-processors. Recently chip vendors have undertaken nascent efforts to make these previously hidden co-processors such as the digital signal processors (DSPs) programmable. In this paper, we explore the energy and performance implications of off-loading the computation associated with machine learning algorithms in context-aware apps to DSPs embedded in mobile SoCs. Our results show a 17% reduction in a TI OMAP4 based mobile platform's energy usage from off-loading context classification computation to the DSP core with indiscernible latency overhead. We also describe the design of a run-time system service for energy efficient context inference on Android devices, which takes parameters from the app to instantiate the classification model and schedules the execution on the DSP or app processor as specified by the app. |
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http://nesl.ee.ucla.edu/fw/chenguang/hotcrp-final44.pdf |
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5th Workshop on Power-Aware Computing and Systems (HotPower'13) |
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2013-11-01 |
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Nemacolin Woodlands Resort, PA |
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| 2013 |
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Towards Analyzing and Improving Robustness of Software Applications to Intermittent and Permanent Faults in Hardware |
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ICCAD: International Conference on Computer Aided Design (ICCAD) 2013 |
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2013-10-01 |
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| 2013 |
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ipShield: A Framework for Enforcing Context-Aware Privacy |
Smart phones are used to collect and often share personal data with untrustworthy third-party apps, leading to data misuse and privacy violations. To mitigate privacy threats Android enforces explicit user permissions for a select set of privacy-prone resources. However, recent research has demonstrated both the inadequacy of this binary access control of resources and the vulnerability of drawing private inferences using combinations of so- called innocuous sensors. We present ipShield, a frame- work that provides users with greater control over their resources at runtime. ipShield performs monitoring of every sensor used by an app and uses this information to perform a privacy risk assessment. In an effort to establish a user-understandable privacy abstraction, the risks are conveyed to the user as a list of possible inferences. Based on user-defined lists of allowed and private inferences, a recommendation of possible privacy actions in the form of which sensors to enable and which to disable is generated. Finally, the user is provided with an option to override the generated actions and manually con- figure context-aware fine-grained privacy rules with actions such as data suppression, noise addition and faking of data streams. We implemented ipShield by modifying AOSP and tested it on a Nexus 4 phone. Our evaluations using computation intensive apps requiring continuous sensor data indicate that ipShield incurs negligible CPU and memory overhead and only a small reduction in battery life. We perform case studies with multiple apps to show the applicability of ipShield under various scenarios. |
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USENIX NSDI 2014 |
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2014-04-01 |
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Inferring Occupancy from Opportunistically Available Sensor Data |
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IEEE Percom |
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2014-03-01 |
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Budapest, Hundary |
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| 2013 |
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It's Different: Insights into home energy consumption in India |
Residential buildings contribute significantly to the overall energy usage across the world. Real deployments, and collected data thereof, play a critical role in providing insights into home energy consumption and occupant behavior. Existing datasets from real residential deployments are all from the developed countries. Developing countries, such as India, present unique opportunities to evaluate the scalability of existing research in diverse settings. Building upon more than a year of experience in sensor network deployments, we undertake an extensive deployment in a three storey home in Delhi, spanning 73 days from May-August 2013, measuring electrical, water and ambient parameters. We used 33 sensors across the home, measuring these parameters, collecting a total of approx. 400 MB of data daily. We discuss the architectural implications on the deployment systems that can be used for monitoring and control in the context of developing countries. Addressing the unreliability of electrical grid and internet in such settings, we present Sense Local-store Upload architecture for robust data collection. While providing several unique aspects, our deployment further validates the common considerations from similar residential deployments, discussed previously in the literature. We also release our collected data- Indian data for Ambient Water and Electricity Sensing (iAWE), for public use. |
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ACM BuildSys |
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2013-11-01 |
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Rome, Italy |
ACM |
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| 2013 |
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Occupancy inferencing from non-intrusive data sources |
Intuitively, measurements from utility meters that are associated with a physical space have embedded in them some information about the occupants of that space. Occupancy information can be sensitive yet empowering. On one hand, with the right information, administrators can adjust subsystems to maximize comfort and energy efficiency. On the other hand, sensitive details about occupants may be leaked. We explore the accuracy to which meter data from physical spaces, when subjected to machine learning algorithms, can yield occupancy information. Our results can then be used to devise low-cost mechanisms for occupancy sensing from the opportunistic use of already available data, and to quantify the risk of leaking privacy-sensitive inferences. |
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ACM BuildSys |
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2013-11-01 |
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| 2014 |
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Hardware Variability-Aware Embedded Software Adaptation |
With scaling of semiconductor fabrication technologies and the push towards deep sub-micron technologies, individual transistors are now composed by a small number of atoms. This makes it difficult to achieve precise control of manufacturing quality, with the added consequence that even slight differences in manufacturing can result in significant fluctuation in critical device and circuit parameters (such as power, performance, and error characteristics) of parts across the die, die-to-die and over time due to changing operating conditions and age-related wear-out. %One aspect of variability with particularly important implications to embedded systems is power variation. Instance and temperature-dependent variation, particularly in power consumption, has a direct impact on application quality and system lifetime for battery powered, energy constrained systems.
In this work we discuss software approaches to handle variability in power consumption of embedded systems. We characterize power variation in contemporary embedded processors, introduce tools for the evaluation of variability-aware software, and focus on two variability-aware software approaches: task activation control through variability-aware duty cycle scheduling and algorithmic choice.
We measured and characterized active and leakage power for a contemporary ARM Cortex M3 processor, and found that across a temperature range of 20--60°C there is 10% variation in active power, and 14x variation in leakage power. As embedded processors in more advanced technologies become commonplace, the variations will increase significantly.
While contemporary hardware already suffers from variability, the evaluation of a variability-aware software stack faces two main challenges: first, commercially available platforms typically do not provide means to ``sense'' or discover variability. Second, even if this sensing capability was available, evaluating a software stack across a statistically significant number of hardware samples and ambient conditions would prove exceedingly costly and time consuming. We introduce VarEMU, an extensible framework for the evaluation of variability-aware software that provides users with the means to emulate variations in power consumption and fault characteristics and to sense and adapt to these variations in software.
We introduce variability aware duty cycling methods and a duty cycle abstractions for embedded operating systems (TinyOS and FreeRTOS) that allow applications to to explicitly specify lifetime and minimum duty cycle or quality requirements for individual tasks, and dynamically adjust duty cycle rates and task activation schedules so that overall quality of service is maximized in the presence of power variability. We show that variability-aware duty cycling yields a 3-22x improvement in total active time over schedules based on worst-case estimations of power, with an average improvement of 6.4x across a wide variety of deployment scenarios based on collected temperature traces. Conversely, datasheet power specifications fail to meet required lifetimes by 7-15%, with an average 37 days short of a required lifetime of one year. Finally, we show that a target localization application using variability-aware duty cycle yields a 50% improvement in quality of results over one based on worst-case estimations of power consumption.
In addition to task activation control though duty cycling, a choice of software to be executed provides further opportunities for optimization. We introduce ViRUS (Virtual function Replacement Under Stress), an application runtime support system that adjusts service quality according to variability-aware policies. In ViRUS, different code paths implement the same function with varying quality-of-service for different energy costs. Mutations from one version to another are triggered by monitoring vectors of variability and energy stress. We demonstrate ViRUS with a framework for transparent function replacement in shared libraries and a polymorphic version of the standard C math library in Linux. Application case studies show how ViRUS can tradeoff upwards of 4% degradation in application quality for a band of upwards of 50% savings in energy consumption.
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http://nesl.ee.ucla.edu/fw/documents/thesis/2014/wanner-phd.pdf |
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PhD Thesis |
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University of California, Los Angeles |
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Efficient Context Inferences and Privacy-Aware Sharing of Sensory Information from Mobile Platforms |
Sensing and sharing of personal sensory information are key aspects in current pervasive mobile sensing applications. Sensing on mobile platforms poses a challenge in efficient resource usage because resource-constrained mobile platforms often perform context inferences that require complex machine learning algorithms. Sharing of personal sensory information also poses a challenge in privacy protection because users have no choice but to store their unfiltered data in third-party cloud services. Such challenges have been individually addressed by prior works, but we propose integrated middleware services on mobile and cloud platforms that provide resource-efficient context inferences and ensure ownership of user’s data. Our flow-based context inference service provides rich node connection and graph control mechanisms that achieve resource efficiency by reducing redundant computations. The inferred contexts are privately stored in our personal cloud service, which enforces privacy-aware sharing through user-defined expressive rules and differentially private aggregates. Our integrated system has been used for a user study with 12 participants, and we show how our system helps users feel less privacy concerned when they sense and share their personal data. We also present benchmark results to show resource savings achieved by the flow-based context service and practical performance of the rule processing on the personal cloud service. |
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http://nesl.ee.ucla.edu/fw/documents/conference/2014/haksoo-mobile-cloud.pdf |
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| 2014 |
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Runtime Optimization of System Utility with Variable Hardware |
Increasing hardware variability in newer integrated circuit fabrication technologies has caused corresponding power variations on a large scale. These variations are particularly exaggerated for idle power consumption, motivating the need to mitigate the effects of variability in systems whose operation is dominated by long idle states with periodic active states. In systems where computation is severely limited by anemic energy reserves and where a long overall system lifetime is desired, maximizing the quality of a given application subject to these constraints is both challenging and an important step towards achieving high quality deployments. This work describes VaRTOS, an architecture and corresponding set of operating system abstractions that provide explicit treatment of both idle and active power variations for tasks running in real time operating systems. Tasks in VaRTOS express elasticity by exposing individual knobs--shared variables that the operating system can tune to adjust task quality and correspondingly task power, maximizing application utility both on a per-task and system-wide basis. We provide results regarding online learning of instance-specific sleep power, active power, and task-level power expenditure on simulated hardware with demonstrated effects for several prototypical applications. Our results show that VaRTOS can reduce variability-induced energy expenditure errors from over 70% in many cases to under 2% in most cases and under 5% in the worst-case. |
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Transactions on Embedded Computing Systems |
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25 |
2014-04-01 |
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ACM |
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