Wireless Sensor Networks for Habitat Monitoring

1. Wireless Sensor Networksfor Habitat Monitoring Alan Mainwaring1 Joseph Polastre2 Robert Szewczyk2 David Culler1,2 John Anderson3 1: Intel Research Laboratory at Berkeley 2: University of California, Berkeley 3: College of the Atlantic

2. Introduction • Application Driven System Design, Research, and Implementation • Parameterizes Systems Research: • Localization • Calibration • Routing and Low-Power Communications • Data Consistency, Storage, and Replication • How Can All of these Services and Systems Be Integrated into a Complete Application?

3. Great Duck Island • Breeding area for Leach’s Storm Petrel (pelagic seabird) • Ecological models may use multiple parameters such as: • Burrow (nest) occupancy during incubation • Differences in the micro-climates of active vs. inactive burrows • Environmental conditions during 7 month breeding season

4. Application > 1000 ft

5. Sensor Network Solution

6. Outline • Application Requirements • Habitat Monitoring Architecture • Sensor Node • Power Management • Sensor Patch • Transit Network • Wide Area Network and Disconnected Operation • Sensor Data • System Analysis • Real World Challenges

7. Application Requirements • Sensor Network • Longevity: 7-9 months • Space: Must fit inside Small Burrow • Quantity: Approximately 50 per patch • Environmental Conditions • Varying Geographic Distances • Inconspicuous Operation • Reduce the “observer effect” • Data • As Much as Possible in the Power Budget • Iterative Process

8. Application Requirements • Predictable System Behavior • Reliable • Meaningful Sensor Readings • Multiple Levels of Connectivity • Management at a Distance • Intermittent Connectivity • Operating Off the Grid • Hierarchy of Networks / Data Archiving

9. Patch Network Sensor Node Sensor Patch Gateway Transit Network Internet Client Data Browsing and Processing Basestation Base-Remote Link Data Service Habitat Monitoring Architecture

10. Sensor Node: Mica • Hardware • Atmel AVR w/ 512kB Flash • 916MHz 40kbps Radio • Range: max 100 ft • Affected by obstacles, RF propogation • 2 AA Batteries • Operating: 15mA • Sleep: 50mA • Software • TinyOS / C Applications • Power Management • Digital Sensor Drivers • Remote Management & Diagnositcs

11. Sensor Node: Power Management • AA Batteries have ~2500 mAh capacity • Mica consumes 50mA in sleep = 1.2 mAh/day Mica Expected Lifetime Expected Lifetime (days) Number of Operating Hours per Day

12. Sensor Node: Power Management • Target Lifetime: 7-8 months • Power Budget: 6.9mAh/day • Questions: • What can be done? • How often? • What is the resulting sample rate?

13. Sensor Node: Mica Weather Board • Digital Sensor Interface to Mica • Onboard ADC • Designed for Low Power Operation • Individual digital switch for each sensor • Designed to Coexist with Other Sensor Boards • Hardware “Enable” Protocol to obtain exclusive access to connector resources

14. Important to Biologists Affect Power Budget Sensor Node: Mica Weather Board

15. Sensor Node: Packaging • Parylene Sealant • Acrylic Enclosures

16. Sensor Patch Network • Nodes: • Approximately 50 • Half in burrows, Half outside • RF unpredictable • Burrows • Obstacles • Drop packets or retry? • Transmit Only Network • Single Hop • Repeaters • 2 hop initially • Most Energy Challenged • Adheres toPower Budget

17. Transit Network • Two implementations • Linux (CerfCube) • Relay Mote • Antennae • No gain antenna (small) • Omnidirectional • Yagi (Directional) • Implementation of transit network depends on: • Distance • Obstacles • Power Budget • Duty cycle of sensor nodes dictates transit network duty cycle

18. Transit Network • Renewable Energy Sources • CerfCube needs 60Wh/day • Assuming an average peak of 1 direct sunlight hour per day: • Panel must be 924 in2or 30” x 30” for a 5” x 5” device! • A mote only needs 2Wh per day, or a panel 6” x 6”

19. Base Station / Wide Area Network • Disconnected Operation and Multiple Levels of State • Laptop • DirecWay Satellite WAN • PostgreSQL • 47% uptime • Redundancy and Replication • Increase number of points of failure • Remote Access • Physical Access Limited • Keep state all areas of network • Resiliency to • Disconnection • Network Failures • Packet Loss • Potential Solution:Keep Local CachesSynchronization

20. Sensor Data Analysis

21. Sensor Data Analysis Outside Burrow Inside Burrow

22. Power Management Goals Calculated 7 months, expect 4 months Battery half-life at 1.2V Predictable Operation Observed per node constant throughput, % loss 739,846 samples as of 9/23, network is still running System Analysis Battery Consumption at Node 57 Packet Throughput and Active Nodes

23. Real World Experiences • System and Sensor Network Challenges • Low Power Operation (low duty cycle) • Affects hardware and software implementation • Multihop Routing • Allows bigger patches • Route around physical obstacles • Must have ~1% operating duty cycle • In Situ Retasking/Reconfiguration • Let biologists interactively change data collection patterns • Not Implemented due to conservative energy implementation • Lack of Physical Access • Remote management • Disconnected operation • Fault tolerance • Reliance on other people and their networks • Physical Size of Device • Affects microcontroller selection, radio, practical choice of power sources

24. Real World Experiences • Failures • Extended Loss of Wide Area Connectivity • Unreliable Reboot Sequence in Windows • Solderless Connections Fail (expansion/contraction cycles) • Node Attrition (Petrels are not mote neutral) • Environmental Conditions (50km/hr gale winds knock over equipment) • Lack of post-mortem diagnositics

25. Conclusions • First long term outdoor wireless sensor network application • Application driven sensor network design • Defines requirements and constraints on core system components (routing, retasking, fault tolerance, power management)

27. Backup Slides

28. Mote 18: Outside

29. Mote 26: Burrow 115a

30. Mote 53: Burrow 115b

31. Mote 47: Burrow 88a

32. Mote 40: Burrow 88b

33. Mote 39: Burrow 84