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 Charlottesville, USA

Motivating Application: Battlefield Surveillance

Other Applications Wildlife Monitoring Alarm System Flock Protection Border Surveillance

Our Solution: VigilNet MICA2 / MICAz / XSM Motes MACSensor Drivers RoutingPower Mngt 1 Signal Filtering Time Sync LocalizationGroup Mngt Power Mng 2 Power Mngt 3 Programming Abstractions Target Classification Velocity / Trajectory Inference Physical Data-Link Routing Middleware Application

Focus of This Presentation: Power Consumption No power management => 4 days lifetime! 99% of energy consumed waiting for potential targets! Energy Distribution

Focus of This Presentation: Power Consumption Power management => 10 months lifetime!  Lifetime x 75 98% of energy consumed in sleep mode! Energy Distribution 98%

State of the Art Topics:  Hardware  Energy Scavenging  Topology Control  Sensing Coverage  Predefined Scheduling  Data Aggregation  Etc… Practicality? Performance in Real Deployments? Applicability to Surveillance System? Combination of Schemes?

Power Management in VigilNet Turning nodes off as often and as long as possible. Questions:  When to turn nodes off (to save power)?  When to wake nodes up (to optimize system performance)?  What are the tradeoffs? Combination of four schemes:  Node level power management.  Group level power management.  Network level power management.  On-demand wakeup.

Group Level: Sentry Selection Redundant Coverage!

Group Level: Sentry Selection Redundant Coverage! => Sentry Selection

Group Level: Sentry Selection Load Balancing?

Group Level: Sentry Selection Load Balancing? => Sentry Rotation

Group Level: Sentry Selection Tradeoff: Detection Latency versus Density Probability of Target Detected Within First 1,000m Number of Nodes in Area 100m x 1,000m ,000 Area 1,000m 100m Radius=20m Radius=8m Radius=2m

Sentry Level: Duty Cycle Scheduling Target Takes Time To Go Through the Network.

Sentry Level: Duty Cycle Scheduling Target Takes Time To Go Through the Network. => Duty Cycle Scheduling

Sentry Level: Duty Cycle Scheduling Putting It All Together

Sentry Level: Duty Cycle Scheduling Tradeoff: Detection Latency Versus Duty Cycle Area 1,000m 100m Probability of Target Detected Within First 1,000m Duty Cycle 40% 100% 0% 20% 1000 Nodes, V=10m/s 1000 Nodes, V=30m/s

Network Level: Tripwire Scheduling Exploiting Knowledge About the Target

Network Level: Tripwire Scheduling Exploiting Knowledge About the Target

Network Level: Tripwire Scheduling Tripwire partition based on distance to a base

On-Demand Wakeup Wakeup Wakeup Path To Base Station Wakeup Nodes For Future Detection

Details of Wakeup Operation Sleeping Node: Wakeup x% of the Time Wakeup Operation: Send Message with Long Preamble

Evaluation by Third Party: Test Field Mote Field 300m X 200m, 200 motes

Evaluation by Third Party: Interactive Display

Evaluation by Third Party: Detection, Classification, and Tracking 1.Initial Detection 2.Classification 3.Periodic updates Average Localization Error: 6.24m Average Velocity Error: 6%

Lifetime Evaluation: Hybrid Simulation

Key Results: Lifetime Lifetime  No Power Management => 4 Days  + Sentry Selection and Rotation => 28 Days  + Duty Cycle Scheduling => 5 Months (12.5% Duty Cycle)  + Tripwire Service => 10 Months (16 Tripwires, ¼ Awake) Tracking Performance Penalty  ~ 3 to 5 Seconds

Key Results: Detection Performance Penalty ~ 3 to 5 Seconds

Summary Successfully integrate 4 power management strategies into real system. Analytical model and extensive simulation to predict system performance under various configurations. Practical feasibility of tracking system using XSM2s with 10 months lifetime.

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