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May18, 2004 General Dynamics Meeting 1
Wireless Sensor Networks and Applications
Cauligi S. Raghavendra
Department of Electrical Engineering
University of Southern California
Los Angeles, CA 90089
http://ceng.usc.edu/~raghu
May18, 2004 General Dynamics Meeting 2
Wireless Sensor Networks
• Wireless Sensor Networks is one of the top 10 Technologies that will change the World in 21st Century– According to MIT Technology Review
• Researchers at USC and ISI Pioneered the field of Sensor Information Technology
• DARPA and NSF have Programs and Initiatives in Sensor Networks
May18, 2004 General Dynamics Meeting 3
Centers, Activities, and Projects
• USC is a Partner in UCLA’s Center for Embedded Networked Sensing (CENS)– NSF Science and Technology Center– Director: Prof. Deborah Estrin, UCLA
• USC SoE Sensing Systems Cluster– http://www.usc.edu/dept/engineering/research/sensornetworks.html
• USC Center for Robotics and Embedded Systems (CRES)– Director: Maja Mataric, USC
• Several Ongoing Projects in EE and CS
May18, 2004 General Dynamics Meeting 4
Some Sensor Nodes
Modern Sensor Nodes
UC Berkeley: COTS Dust
UC Berkeley: COTS DustUC Berkeley: Smart Dust
UCLA: WINS Rockwell: WINS JPL: Sensor Webs
May18, 2004 General Dynamics Meeting 5
Characteristics of Sensor Networks
• Sensor Nodes – Limited Battery Life
• Capacity – CPU, Memory
• Limited Software Support
• Ad Hoc Networks with Low Bandwidth
• No Network Infrastructure
• Link Quality – Fading and Interference
• Deployment – Less Control
May18, 2004 General Dynamics Meeting 6
Research Challenges
• Interdisciplinary Research • Application Aware Research• New Networking Paradigms and Protocols• Self Organization and Localization• Incomplete and Inaccurate Field Data• Energy Efficient Algorithms and Protocols• Embedded Environments and Deployment
May18, 2004 General Dynamics Meeting 7
Research in School of Engineering
• EE, CSCI, CE, BME Departments, and ISI
• Profs. Helmy, Krishnamachari, Kumar, Lee, Mitra, Mendel, Narayanan, Ortega, Prasanna, Raghavendra
• Profs. Govindan, Sukhatme, Requicha• Profs. J. Caffrey, E. Johnson, S. Masri• Dr. Heidemann and others at ISI
May18, 2004 General Dynamics Meeting 11
Situation Awareness
Periodic Voice Traffic
Internet Connectivityto Mission HQ
Squad
Energy Efficient one-to-all and All-to-all Broadcasting Algorithms
100-300% Improvement for Situation Awareness in Ad hoc Networks
Energy Efficient one-to-all and All-to-all Broadcasting Algorithms
100-300% Improvement for Situation Awareness in Ad hoc Networks
May18, 2004 General Dynamics Meeting 12
Power Aware Computing and Commn.
Multi-Level Power Management in Distributed Battlesite/Sensor Network (PAC/C Program)
Task
Algorithm
Protocol
Physical
May18, 2004 General Dynamics Meeting 13
Multiple nodes Sensedata and Coordinate
Multiple nodes Sensedata and Coordinate
Distributed Computationin Sensor Networks
Application:Target Detection
Application:Target Detection
•Power Aware Node Selection•Task Allocation•Collaboration•Signal Processing•Wireless Communication
•Power Aware Node Selection•Task Allocation•Collaboration•Signal Processing•Wireless Communication
Non-participating node
Selected node
Selection / Query
T1
T4
T3
T2
T5
May18, 2004 General Dynamics Meeting 14
Acoustic Sensors
• Sensor database provided by the Army Research Laboratory (acoustic and seismic)
• Microphone arrays are typically 4 ft – 8 ft in diameter, not restricted to a specific geometry
• Inexpensive, passive and non-line of sight capabilities
Acoustic Sensor Array - RNADS
Courtesy of N. Srour, Army Research Lab
May18, 2004 General Dynamics Meeting 15
Spatio-Temporal Correlation in Sensor Data
Compress data to reduce storage and communication bandwidth!
May18, 2004 General Dynamics Meeting 16
A Distributed Algorithm for Waking-up in Heterogeneous Sensor Networks
2
1
3
5
4
{1,5}
{1}
{1}{1 ,2}
{1}
{1 ,5}
{4 ,5}
{3 ,4}
{3 ,4}
{2 ,3}
{2 ,3}
{i1,i2,...,iK}: set of chosen trackersTracker Off
Tripw ire Detect
Tripw ire Sense
Detection Area
2
1
3
5
4
{1,2}
{1 ,2}{1 ,2}
{1 ,2}
{1 ,2}
{1 ,2}
{1 ,2}
{1 ,2}
{1 ,2}
{1 ,2}
i Tracker On"w ake-up"
{1 ,2}
Event occurs
N tripwires detect event
Detecting tripwires run distributed algorithm => choose K optimal trackers
wake-up chosen trackers
6
15
2536
4964
0
50
100
150
200
250
total message
s
M
N
Message Complexity
200-250
150-200
100-150
50-100
0-50
Performance under link losses
05
10152025303540
0 5 10 15 20 25 30 35 40 45 50
link loss probability (%)
no
n-c
on
verg
ing
no
des
(%)
Convergence delay vs. link loss
0
20
40
60
80
100
120
0 5 10 15 20 25 30 35 40 45 50
link loss probability (%)
dela
y (
ms)
RESULTS
May18, 2004 General Dynamics Meeting 17
False Alarm Detection in Wireless Sensor Network
Node Data
0
1000
2000
3000
1 186 371 556 741 926
Milliseconds
Am
plit
ud
es
False Alarm Data
1400
1500
1600
1700
1 184 367 550 733 916
Milliseconds
Am
plit
ud
es
False Alarm Data
-2500
-5001500
35005500
1 201 401 601 801 1001
Milliseconds
Am
plit
udes
Node Data
-2500-500150035005500
1 201 401 601 801 1001
Milliseconds
Am
plit
ud
es
Energy in subbands are evenly distributed (no variation)
Binary subband search
Linear search is slow
• In search iteration, pick the subband with larger energy and compare with a threshold
• Negative if greater than the threshold
• Report false alarm in the end
• It is possible detected signal is due to noise• Processing such noise data leads to unnecessary use of resources• False alarm detection help to save energy significantly
May18, 2004 General Dynamics Meeting 18
Traffic shaping to mitigate Hotspots
Cluster based Traffic Shaping• Cluster
– Scheduled data collection within cluster• Data Combination (DC)
– Packet size vs. Packet number• Rate Adaptation (RA)
– Adapt rate according to latency bound• Traffic Dispersal (TD)
– Spread data traffic away from hot spot
2 3 4 5 6 7 8 9 100
50
100
150
200
250
Sensor Message Arrival Interval (second)
Ene
rgy
Eff
icie
ncy
(Pac
ket/
Joul
e)
CSMARARA+DCRA+DC+TD
2 3 4 5 6 7 8 9 100
0.2
0.4
0.6
0.8
1
Sensor Messsage Arrival Interval (second)
Del
iver
y R
atio
CSMARARA+DCRA+DC+TD
May18, 2004 General Dynamics Meeting 19
Structural Health Monitoring
• Goal: Design sensor networks for improving the safety of structures (buildings, bridges, ships, aircraft, spacecraft)
• Research focuses:– Local excitation based
damage identification– System components for fine-
grain structural monitoring
• Multi-disciplinary effort:– John Caffrey (CE),
Ramesh Govindan (CS),Erik Johnson (CE),Bhaskar Krishnamachari (EE),Sami Masri (CE),Gaurav Sukhatme (CS)
May18, 2004 General Dynamics Meeting 20
Courses and Conferences
• ACM Wireless Sensor Networks and Applications Workshop• IEEE SECON Conf. in October 2004• Edited Book on Wireless Sensor Networks
• Pertinent Courses Offered:– Advanced Topics in Computer Networks and Distributed
Systems (Prof. Ramesh Govindan, CS 694)– Wireless Sensor Networks (Prof. Bhaskar Krishnamachari, EE
652)– Intelligent Embedded Systems (Prof. Gaurav Sukhatme, CS
546)– Wireless Networking, Design and Analysis Laboratory (Prof.
Ahmed Helmy, EE 599)
May18, 2004 General Dynamics Meeting 21
Faculty Contact Information
• A. Helmy, [email protected], (213) 821-1329• B. Krishnamachari, [email protected], (213) 821-2528• V. Kumar, [email protected], (213) 740-4668• D. Lee, [email protected], (213) 740-0882• U. Mitra, [email protected], (213) 740-4667• J. Mendel, [email protected], (213) 740-4445• S. Narayanan, [email protected], (213) 740-6432• A. Ortega, [email protected], (213)740-• V. Prasanna, [email protected], (213) 740-4483• C. Raghavendra, [email protected], (213) 740-9133• R.Govindan, [email protected], (213) 740-4509• G. Sukhatme, [email protected], (213) 740-0218u• A. Requicha, [email protected], (213) 740-4502• J. Caffrey, (213) 740-0603• E. Johnson, [email protected], (213) 740-0610• S. Masri, [email protected], (213) 740-0602• J. Heidemann, [email protected], (310) 448-8708