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Wireless Sensor Networks for Habitat Monitoring Alan Mainwaring 1 Joseph Polastre 2 Robert Szewczyk...
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Transcript of Wireless Sensor Networks for Habitat Monitoring Alan Mainwaring 1 Joseph Polastre 2 Robert Szewczyk...
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
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
Transit Network
Basestation
Gateway
Sensor Patch
Patch Network
Base-Remote Link
Data Service
Internet
Client Data Browsingand Processing
Sensor Node
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: 50A
• Software – TinyOS / C Applications– Power Management– Digital Sensor Drivers– Remote Management & Diagnositcs
Sensor Node: Power Management
• AA Batteries have ~2500 mAh capacity• Mica consumes 50A in sleep = 1.2 mAh/day
Node Activity Days Years
Mica Always On 7 0.1
Mica Always Sleeping 2081 5.7
Number of Operating Hours per Day
Exp
ecte
d Li
fetim
e (d
ays
)
Mica Expected Lifetime
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
+ CPU 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 1 K 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 3 K 5% 2000 Hz 200 ms 0.170 mA
Thermistor 5 K 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 toPower 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
– 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”
SizeW/in065.0
1
Hoursr Peak Winte
Dayper Hours WattsTotal2
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
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
• Predictable Operation– Observed per node constant
throughput, % loss– 739,846 samples as of 9/23,
network is still runningBattery Consumption at Node 57 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