1 Achieving Long-Term Surveillance in VigilNet Tian He, Pascal Vicaire, Ting Yan, Qing Cao, Gang Zhou, Lin Gu, Liqian Luo, Radu Stoleru, John A. Stankovic,
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Slide 1
1 Achieving Long-Term Surveillance in VigilNet Tian He, Pascal
Vicaire, Ting Yan, Qing Cao, Gang Zhou, Lin Gu, Liqian Luo, Radu
Stoleru, John A. Stankovic, Tarek F. Abdelzaher Department of
Computer Science, University of Virginia IEEE Infocom 2006
Slide 2
2 outlines Introduction Power management Power management in
VigilNet System implementation System evaluation Conclusion
Slide 3
3 Introduction VigilNet An Integrated Sensor Network System for
Energy-Efficient Surveillance Goal : to achieve long-term
surveillance in a realistic mission deployment. long-term : minimum
3 ~6 months life time
http://www.cs.virginia.edu/~control/SOWN/index.h tml
http://www.cs.virginia.edu/~control/SOWN/index.h tml
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4
Slide 5
5 Introduction Energy efficiency Single protocol : the hardware
design coverage MAC routing data dissemination data gathering data
aggregation data caching topology management clustering
placement...etc. Our : an integrated multi-dimensional power
management system. tripwire service sentry service duty cycle
scheduling
Slide 6
6 Introduction Contributions 1) Our design is validated through
an extensive system implementation: VigilNet a large-scale sensor
network system delivered to military agencies. 2) VigilNet takes a
systematic approach. We propose a novel tripwire service,
integrated with an effective sentry and duty cycle scheduling to
increase the system lifetime. 3) We devote considerable effort to
evaluate the system with 200 XSM motes in an outdoor environment
and an extensive simulation of 10,000 nodes.
Slide 7
7 Power management Sampling System regular reporting Ex : Great
Duck Island Predefined sampling schedules Nodes can conserve energy
by turning themselves off, according to a predefined schedule.
Synchronized and coordinated operations Once the sampling interval
is defined a priori, nodes can communicate in a synchronized
fashion. Data aggregation and compression Since channel media
access is costly, especially when the receiver is in a deep-sleep
state
Slide 8
8 Power management Surveillance System : event-driven Coverage
control activating only a subset of nodes at a given point of time,
waiting for potential targets. Duty cycle scheduling By
coordinating nodes sleep schedules, we can conserve energy without
noticeably reducing the chance of detection. Incremental activation
First activate only a subset of sensors for the initial detection,
then activate other sensors to achieve a higher sensing
fidelity.
Slide 9
9 Power management in VigilNet Power management requirements in
VigilNet Continuous surveillance VigilNet is a military
surveillance application. Real-time VigilNet is a real-time online
system for target tracking. Rare and critical event detection
VigilNet deals with the rare and critical event model. In this
model, the total duration of events is small. Stealthiness Deployed
in hostile environments, miniaturization makes nodes hard to
detect. Flexibility the deployment of VigilNet is under different
densities, topologies, sensing and communication capabilities.
Slide 10
10 Power management in VigilNet 3 main power management
strategies in VigilNet tripwire service sentry service duty cycle
scheduling
Slide 11
11 Tripwire Services Divides the sensor field into multiple
sections, called tripwire sections, and applies different working
schedules to each tripwire section. A tripwire section can be
either in an active or a dormant state.
Slide 12
12 Tripwire Services Tripwire partition VigilNet implements its
tripwire partition policy based on the Voronoi diagram. Can reduce
the energy consumption and the end-to-end delay in data delivery. A
network with n bases is partitioned into n tripwire sections and
each tripwire section contains exactly one base i. Every node in
the network uniquely belongs to one and only one tripwire section.
The base placement strategy is normally determined by the mission
plan and topology.
Slide 13
13 Tripwire Services Tripwire partition mechanism 1) each base
broadcasts one initialization beacon to its neighbors with a hop
count parameter initialized to one 2) Each receiving node maintains
the minimum hop- count value of all beacons it received from the
nearest base, in terms of the physical distance. Supported
partition policies Hop count (currently used) Distance
Slide 14
14 Data Structure Maintenance TripWire Table Max Num of
TripWire Base a node can remember, currently set be 5 TripWire
IDHopsstatus (active, dormant)
Slide 15
15 12 Green: Base (active), Blue: Base (dormant), Yellow: Motes
Red: example node 141 230
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16 12 Green: Base (active), Blue: Base (dormant), Yellow: Motes
Red: example node 141 220
Slide 17
17 12 Green: Base (active), Blue: Base (dormant), Yellow: Motes
Red: example node 121 220 350 5100 6151 8 ... Find min hop, if it
choose the first one
Slide 18
18 Tripwire Services
Slide 19
19 Tripwire Services Tripwire scheduling Configure the state of
each tripwire section by setting a 16 bits schedule. Each bit in
the schedule denotes the state of this tripwire section in each
round (rotation) up to 16 rounds. After 16 rounds, the pattern is
repeated. Can assign 65536 different schedules to each tripwire and
assign 65536^N (N is the number of tripwires.) different schedules
to the network. The schedule can be predetermined or randomly
generated. Random scheduling is done by setting the Tripwire Duty
Cycle (TDC), which is the percentage of active rounds in the
schedule.
Slide 20
20 Sentry service The main purpose of the sentry service is to
select a subset of nodes, called sentries. 2 phases 1) Nodes
exchange neighboring information through hello messages. a sender
attaches its node ID, position, number of neighbors and its own
energy readings. 2) each node sets a delay timer Renergy : weighted
Energy rank Rcover : weighted Cover rank Our : Renergy =
Rcover
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21 Sentry service Range of Vicinity (ROV) The effective range,
in physical distance, of a sentrys declaration message. 1) How to
choose ROV? The sentry density is upper bounded by to achieve a 99%
detection probability a sentry density of 0.008 nodes/m2 (ROV= 6
meters) with 8 meter sensing range a lower density of 0.004
nodes/m2 (ROV=8.5 meters) with 14 meters sensing range
Slide 22
22 Sentry service 2) How to enforce ROV ? discard declaration
messages from any sentry beyond the distance of ROV. provides a
more predictable sentry distribution Localization[38] is supported
in VigilNet.
Slide 23
23 Sentry duty cycle scheduling Ton be the active duration Toff
be the inactive duration Sentry Toggle Period (STP) : Ton + Toff
Sentry Duty Cycle (SDC) : Ton / STP lowering the SDC value
increases the detection delay and reduces the detection probability
Use random duty cycle scheduling, not the sophisticated / optimal
scheduling algorithms[33] to coordinate node activities to maximize
performance
Slide 24
24 Integrated solution tripwire service controls the network-
wide distribution of power consumption among sections Tripwire Duty
Cycle (TDC), the percentage of active time for each tripwire
section, to control the network- wide energy burning rate. sentry
service controls the power distribution within each section. use
the Range of Vicinity (ROV) parameter to control the energy-burning
rate of active sections. duty cycle scheduling controls the
energy-burning rate of individual sentry nodes Sentry Duty Cycle
(SDC) parameter is used to control the awareness of sentry nodes,
which is the percentage of active time
Slide 25
25 System implementation
Slide 26
26 System implementation OS : TinyOS Language : NesC Code size
: about 40,000 lines of code, supporting MICA2 and XSM mote
platforms. 83,963 bytes of code memory 3,586 bytes of data memory
Nodes are randomly placed roughly 10 meters apart, deployed 200 XSM
motes on a dirt T-shape road (200 * 300 meters).
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27
Slide 28
28 System evaluation
Slide 29
29 The Voronoi-based tripwire partitioning is very effective
and that all nodes attach to the nearest base nodes through the
shortest path.
Slide 30
30
Slide 31
31 It is not the case that nodes with high voltages are always
selected as sentries. The average minimum distances between sentry-
pairs is 9.57 meters with 1.88 meters standard deviation.
33 SSA (Sentry Service Activation) 1)To reduce the detection
delay, choose a sentry toggle period as small as possible. 2)To
increase the network lifetime, select a small sentry duty cycle.
SDC, detection delay
Slide 34
34 SDC, detection prob
Slide 35
35 STP, detection delay STP, detection prob
Slide 36
36 a low tripwire duty cycle(TDC) increases the network
lifetime, but increases the detection delay and decreases the
detection probability TDC, detection prob TDC, detection delay
Slide 37
37 it takes more time to detect slow targets than faster ones;
a high target speed decreases the detection delay Target speed ,
detection delay
Slide 38
38 Conclusions It is a comprehensive case study on power
management in a realistic environment with a large testbed.
Investigate the power management at the network, section and node
level by using a novel tripwire service, sentry service and duty
cycle scheduling, respectively.
Slide 39
39 References [7] T. Yan, T. He, and J. Stankovic,
Differentiated Surveillance Service for Sensor Networks, in SenSys
2003, November 2003. [33] Q. Cao, T. Abdelzaher, T. He, and J.
Stankovic, Towards Optimal Sleep Scheduling in Sensor Networks for
Rare Event Detection, in IPSN05, 2005. [37] G.Simon and et. al.,
Sensor Network-Based Countersniper System, in SenSys 2004, November
2004. [38] T. He, S. Krishnamurthy, J. A. Stankovic, and T.
Abdelzaher, An Energy-Effi cient Surveillance System Using Wireless
Sensor Networks, in MobiSys04, June 2004. [39] R. Stoleru, T. He,
and J. A. Stankovic, Walking GPS: A Practical Solution for
Localization in Manually Deployed Wireless Sensor Networks, in
EmNetS-I, October 2004. [41] G. Zhou, T. He, and J. A. Stankovic,
Impact of Radio Irregularity on Wireless Sensor Networks, in
MobiSys04, June 2004. [43] T. He, C. Huang, B. M. Blum, J. A.
Stankovic, and T. Abdelzaher, Range-Free Localization Schemes in
Large-Scale Sensor Networks, in MOBICOM03, September 2003. [44] T.
He, B. M. Blum, J. A. Stankovic, and T. F. Abdelzaher, AIDA:
Adaptive Application Independent Data Aggregation in Wireless
Sensor Networks, ACM Transactions on Embedded Computing System,
Special issue on Dynamically Adaptable Embedded Systems, 2004.
http://www.cs.virginia.edu/~control/SOWN/index.html
http://www.xbow.com
Slide 40
40 References Tian He, Pascal Vicaire, Ting Yan, Qing Cao, Gang
Zhou, Lin Gu, Liqian Luo, Radu Stoleru, John A. Stankovic, and
Tarek Abdelzaher. Achieving Long-Term Surveillance in VigilNet.
IEEE Infocom, April 2006. Liqian Luo, Tian He, Gang Zhou, Lin Gu,
Tarek Abdelzaher, and John Stankovic. Achieving Repeatability of
Asynchronous Events in Wireless Sensor Networks with EnviroLog.
IEEE Infocom, April 2006 Qing Cao, Tian He, Lei Fang, Tarek
Abdelzaher, John Stankovic, and Sang Son. Efficiency Centric
Communication Model for Wireless Sensor Networks. IEEE Infocom,
April 2006 Gang Zhou, Chengdu Huang, Ting Yan, Tian He, and John A.
Stankovic. MMSN: Multi-Frequency Media Access Control for Wireless
Sensor Networks. IEEE Infocom, April 2006