Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Wireless Sensor Networks for Habitat Monitoring
Wireless Sensor Networks for Habitat Monitoring
Alan Mainwaring, Joseph Polastre, Robert Szewczyk, and David Culler, June 2002
Alan Mainwaring, Joseph Polastre, Robert Szewczyk, and David Culler, June 2002
Presented by Team 8:
Feng Kai and Michael Thomsen,
September 2004
Presented by Team 8:
Feng Kai and Michael Thomsen,
September 2004
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
OutlineOutline
• Habitat monitoring• Network Requirements• System Architecture• Hardware and Design• Results
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Why?Why?
Why are we interested in Habitat Monitoring?• Focus attention on a REAL network• Some problems have simple concrete solutions, while others
remain open research areas• Application driven approach separates actual problems from
potential ones, and relevant issues from irrelevant ones• Collaboration with scientists in other fields helps define
broader application space as well as scientific requirements
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
• How much can they vary?• What are the occupancy patterns during incubation?• What environmental changes occurs in
the burrows and their vicinity duringthe breeding season?
Scientific MotivationScientific Motivation
Questions• What environmental factors make for a good nest?
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Scientific MotivationScientific Motivation
• Collect detailed occupancy data from a number of occupied and empty nests
• Validate a sample of sensor data with a different sensing modality
• Augment the sensor data with deployment notes (e.g. burrow depth, soil consistency, vegetation data)
• Try to answer the questions based on analysis of the entire data set
Methodology• Characterize the climate inside and outside the burrow
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Scientific MotivationScientific Motivation
Solution• Deployment of a sensor network
• The impact of human presence can distort results by changing behavioral patterns and destroy sensitive populations
• Repeated disturbance will lead to abandonment of the colony
Problems• Seabird colonies are very sensitive to disturbances
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Field StationsField Stations
Great Duck Island• Almost 1 km2 (237 acre) remote island• Coast of Maine• Large Breeding colonies of Leech’s
Storm Petrels and other seabirds
James San Jacinto Mountains Reserve• Small 0,1 km2 (29 acre) ecological preserve• Near Idyllwild, California
(about 100 km east of LA)• Studying nest boxes, and
ecosystems over time
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Application RequirementsApplication Requirements
• Hierarchical network (local networks over longer distances)• Sensor network longevity (at least 9 months)• Operating off-the-grid (battery or solar cells) • Remote management (personnel just available 2-3 months)• Inconspicuous operation (should not disrupt natural
processes or behaviors under study)• System behavior (stable, predictable and repeatable behavior)• In-situ interactions (during deployment and maintenance)• Sensors and sampling (light, temperature, IR, humidity,
pressure)
General Requirements• Internet access
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Patch Network
Gateway(low power)
System ArchitectureSystem Architecture
Base-Remote Link
Data Service
Internet
Client Data Browsingand Processing
Transit Network
Base-station(house-hold power)
Sensor Patch
Sensor Node(power)
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Sensor NodesSensor Nodes
• Sensor nodes communicate andcoordinate with one another
• Battery powered• Small (5 x 3.8 x 1.25 cm3)• Mechanically robust• Weather-proofed (but ventilated
to avoid data distortion)
Sensor Nodes• Separated into two logical components:
• Computational module (MICA)• Sensing Module (Weather board)
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Sensor NodesSensor Nodes
Computational Module• Mica Platform
• Atmel Atmega 103 micro controller @ 4 MHz• 512 kb Flash memory• 916 MHz, 40 kbps radio• 2 AA batteries w/boost converter
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Sensor NodesSensor Nodes
Sensor Module• Mica Weather Board
• Temperature• Photoresistor• Barometric pressure• Humidity• Passive IR (Thermopile)
• Designed to coexist with other sensor boards• Low variation when interchanged with other sensors of same
model
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Power ManagementPower Management
Sensor Node Power• Limited Resource (2 AA batteries)• Estimated supply of 2200 mAh at 3 volts• Each node has 8.128 mAh per day (9 months)• Sleep current 30 to 50 uA (results in 6.9 mAh/day for tasks)• Processor draws apx 5 mA => can run at most 1.4 hours/day• Nodes near the gateway will do more forwarding
75 minutes
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Power ManagementPower Management
Compression• Does the compression require more power than transmission?• Even if it does it may be worthwhile to compress if data must
pass through many nodes• 2 - 4 times reduction by combining:
• Delta compression and• Standard compression algorithm:
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
GatewayGateway
Function• Relay sensor patch network data to base station• Coordinate the activity within the sensor patch• Provides additional computation and storage• Gateway to base station distance apx 100 m
Hardware• Strong-Arm based embedded system (CerfCube)• Runs an embedded version of Linux• Compact Flash memory• 2.5 W supplied by solar cells and lead-acid battery
inches
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Base StationBase Station
• Connects to the Internet:• Great Duck Island: Two-way satellite• James Reserve: T1 line
Base Station• Laptop:
• Coordinates the sensor patches• Provides database service
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
The GizmoThe Gizmo
In situ Interaction (Planned)• PDA-sized device• Communicate directly with the sensor patch• Direct communication to the mote• Provides fresh readings• Interactively control the network (sampling rates, power
management etc)• Useful during initial deployment and
retasking of the network
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
CommunicationCommunication
Routing• Routing directly from node to gateway not possible• Approach proposed for scheduled communication:
• Determine routing tree• Each gate is assigned a level based on the tree• Each level transmits to the next and returns to sleep• Process continues until all level have completed
transmission• The entire network returns to sleep mode• The process repeats itself at a specified point in the future
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Network RetaskingNetwork Retasking
Network Retasking• Initially collect absolute temperature readings• After initial interpretation, could be realized that information of
interest is contained in significant temperature changes• Full reprogramming process is costly:
• Transmission of 10 kbit of data• Reprogramming application: 2 minutes @ 10 mA• Equals one complete days energy
• Virtual Machine based retasking:• Only small parts of the code needs to be changed
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
ConclusionConclusion
Paper conclusion• Two small scale sensor networks deployed at
Great Duck Island and James Reserve (one patch each)• Results not evaluated• No calibration was done, development of auto-calibration
procedure suggested
Future• Develop a habitat monitoring kit
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
ProblemsProblems
• Base Station laptop must run unattended (problem with unscheduled system reboots (mostly fixed))
• Temperature Sensors:• Measured temperature inside the enclosure, rather than
ambient temperature• Good correlation with Cost Guard measurements on cloudy
days • Batteries:
• Only operational down to 2.5 V (expected down to 1.6V)
2002 Deployed Network• No new science about petrel breeding behavior, many insights
into how to build sensors that would yeild that science
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
ProblemsProblems
2002 Deployed Network• Rain affecting the humidity sensor and short-circuiting the
battery
0 10 20 30 40 50 60 700
0.2
0.4
0.6
0.8
1
Po
pu
lati
on
att
riti
on
(%
)
Time (days)
Failed humidity sensorTotal node population
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
Additional ReferencesAdditional References
• R. Szewczyk, J. Polastre, A. Mainwaring, D. Culler: ”Lessons from a Sensor Network Expedition”, UC Berkerly, Jan 2004
• J. Polastre: ”Design and Implementation of Wireless Sensor Networks for Habitat Monitoring”, Research Project, 2003
• www.greatduckisland.net
Team 8 – Feng Kai and Michael Thomsen02202, September 7th, lecture 2
2003 Network2003 Network
New design• Lithium battery based• New enclosure
Burrow, Ground, D-Cell, 2002 Ground
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