1. Review: Analysis of Wireless Sensor Networks for Habitat Monitoring Polastre, Szewczyk, Mainwaring, Culler
Review by Nate Ota
CS294
8/28/03

2. The Application: Great Duck Island
Motivation: use a habitat monitoring application to deploy a long term network
Problem
Human interaction impact w/ environment
Node interaction impact w/ environment
“shadowing effect”
Cost of equipment and personnel
Approach
Use tiered architecture sensor network to address problems and make data available locally and remotely (sensor patch, gateway, base station)

3. The Application: Great Duck Island
Dimension
Spatial
Temporal
scale - sampling
cubic meter (size of burrow)
seconds (70) and duration of events
scale - extent
10's (43)
constant
scale - density
sparsely located dense patches (<= 50 patches)
1 node: 1 burrow constant
variability - structure
none
 none
variability - task
low
variability - space
autonomy - modalities
light, thermistor, humidity, thermopile
subset of spatial
autonomy - complexity
low - sends data to DB

4. Packet Loss Expected 4.8M, Actual 1.1M readings
Pattern of packet loss despite expected CSMA correction
Sources
Packet collisions
Clock skew and capture effect
Not major source of loss
Use signal strength meter to avoid false “pkts”
Environmental Conditions
Failed temp correlated to failed humidity sensors
High humidity correlated with significant voltage drop
Battery state
Drain due to moisture, but not a cause of node failure
Related to high moisture

5. Power Management Only 5 nodes exhaust battery Non-graceful degradation
Battery not meant periodic use

6. Last Points Failure Battery matching to application
Abnormally high moisture
Clock skew
Exposure to wildlife
Battery matching to application
Sensor readings can be used to predict node failure

7. Before the slaughter…
Anyone need a partner for the assignment