Wireless Sensor Networks for 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.
Download ReportTranscript Wireless Sensor Networks for 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.
Wireless Sensor Networks for 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 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? 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 Application > 1000 ft Sensor Network Solution 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 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 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 Habitat Monitoring Architecture Patch Network Sensor Node Sensor Patch Gateway Transit Network Client Data Browsing and Processing Basestation Base-Remote Link Internet Data Service 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 Sensor Node: Power Management Expected Lifetime (days) • AA Batteries have ~2500 mAh capacity • Mica consumes 50mA in sleep = 1.2 mAh/day Mica Expected Lifetime Number of Operating Hours per Day Node Activity Days Years Mica Always On 7 0.1 Mica Always Sleeping 2081 5.7 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? Operation nAh Transmitting a packet 20.000 Receiving a packet 8.000 Radio Listening for 1ms 1.250 Operating Sensor for 1s (analog) 1.080 Operating Sensor for 1s (digital) 0.347 Reading a Sample from the ADC 0.011 Flash Read Data 1.111 Flash Program/Erase Data 83.333 Operation Operating Time per Day Duty Cycle Sample Rate Always Sleep 24 hours 0% 0 samples/day + mCPU on 52 minutes 3.61% 0 samples/day + Radio On (Listen) 28 minutes 1.94% 0 samples/day + Sample All Sensors 21 minutes 1.45% 630 samples/day + Transmit Samples 20 minutes 1.38% 600 samples/day 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 Sensor Node: Mica Weather Board Sensor Accuracy Interchange Max Rate Startup Current Photo N/A 10% 2000 Hz 10 ms 1.235 mA I2C Temp 1K 0.2 K 2 Hz 500 ms 0.150 mA Pressure 1.5 mbar 0.5% 10 Hz 500 ms 0.010 mA Press Temp 0.8 K 0.24 K 10 Hz 500 ms 0.010 mA Humidity 2% 3% 500 Hz 500 ms 0.775 mA Thermopile 3K 5% 2000 Hz 200 ms 0.170 mA Thermistor 5K 10% 2000 Hz 10 ms 0.126 mA Important to Biologists Affect Power Budget Sensor Node: Packaging • Parylene Sealant • Acrylic Enclosures Sensor Patch Network • Transmit Only Network • Single Hop • Repeaters – 2 hop initially – Most Energy Challenged • Adheres to Power Budget • Nodes: – Approximately 50 – Half in burrows, Half outside – RF unpredictable • Burrows • Obstacles • Drop packets or retry? 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 Transit Network • Renewable Energy Sources T otalWattsHours per Day 1 Size Peak Winte r Hours 0.065W/in2 – CerfCube needs 60Wh/day – Assuming an average peak of 1 direct sunlight hour per day: – Panel must be 924 in2 or 30” x 30” for a 5” x 5” device! – A mote only needs 2Wh per day, or a panel 6” x 6” 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 Caches Synchronization Sensor Data Analysis Sensor Data Analysis Outside Burrow Inside Burrow System Analysis • Power Management Goals – Calculated 7 months, expect 4 months – Battery half-life at 1.2V Battery Consumption at Node 57 • Predictable Operation – Observed per node constant throughput, % loss – 739,846 samples as of 9/23, network is still running Packet Throughput and Active Nodes 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 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 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) Backup Slides Mote 18: Outside Mote 26: Burrow 115a Mote 53: Burrow 115b Mote 47: Burrow 88a Mote 40: Burrow 88b Mote 39: Burrow 84