EnergyEfficient Computing for Wildlife Tracking

1
Energy-Efficient Computing for Wildlife Tracking

• Design Tradeoffs and Early Experiences with
  ZebraNet
• Chris Roedel
• Wednesday, August 12, 2009

2
Overview

• Background Information
• Other Sensor Networks
• ZebraNet Design Goals
• Life as a Zebra
• Collar Design
• Protocol Design
• Experimental Results
• Discussion Questions

3
Background Information

• Biology researchers want to track and monitor
  wild animals
• Long term
• Over long distances
• Need detailed information about what the animals
  do to see how environment affects them
• Current tracking techniques are far too primitive
  and are not very useful to researchers

4
Why Other Networks Wont Suffice

• No infrastructure to support Wired Networks
  Wireless
• Flying over an area and looking for VHF ping
  signals
• Can miss interesting events
• Limited to daylight hours
• Hard to obtain data from reclusive species
• GPS Satellite Uploads
• Most sophisticated system can only store 3000
  position entries no biometric data
• Satellite uploads are slow, power hungry and
• Peer to Peer offers opportunity to improve

5
What makes ZebraNet Unique???

• First system to employ both mobile nodes AND
  mobile base stations
• Specialized communication models that funnel data
  towards a base station and optimized for a high
  degree of latency tolerance
• Examine energy tradeoffs using real system energy
  measurements from prototype in operation

6
Design Goals for ZebraNet

• GPS Position taken every 3 minutes
• Detailed activity logs for 3 minutes / hour
• 1 year untouched operation
• Operation over 100s or 1,000s of sq km

• Latency is not critical, but high probability for
  delivering all data eventually
• Zebra collar weight limit of 3-5 lbs.
• No fixed base stations, antennas, or cell service

7
Day to Day as a Zebra

• Social Structure
• One type of Zebra moves in Harems
• Generally, only one male in the harem
  reducing the number of collars need to track a
  large number of zebras
• Groups of Harems form Herds
• These dynamics challenge ecologists, but will
  help ZebraNet transfer information between
  harems
• Movement Patterns
• Distance Moved
• Net distance moved in a 3 minute period
• One of three groups Grazing, Graze-Walking, Fast
  Moving
• Turning Angle
• How far does the animal turn during each of the 3
  phases
• Water Sources and Drinking
• Need to find water sources at least once per day
• Sleep
• Must rely on keeping watch and fleeing from
  predators

8
Zebra Movement Speeds

• From Field Data
• Grazing
• 0.017m/s
• Graze-walking
• 0.072 m/s
• Fast
• 0.155 m/s
• Turns

9
Non-Intrusive Necklace Design

• GPS, Flash RAM CPU
• Short Range Radio
• Long Range Radio w/ Packet Modem
• Does not show
• Packaging
• Batteries
• Solar Array
• Power Management Circuits

Put that on my neck and Ill show you my
non-intrusive design
10
Power and Weight Information
Total Weight Goal 3-5 lbs. Energy Goal 5 days
if no recharge
11
Basic Protocol in Action
Harem A and Harem B come within short range radio
range. They transfer their own information with
each other
12
Basic Protocol in Action
Harem A and Harem B move away from each other,
but Harem B moves within range of Harem C,
transferring both Bs and As information to C.
Harem C transfers its information to B.
13
Basic Protocol in Action
Now Harem C is within Long Range Radio range of
the mobile base station and can transfer its
information along with Bs and As. The base
station has the information from all the animals
even though it only came within range of Harem C.
14
Protocol Design

• Two peer-to-peer protocols evaluated here
• Flooding Send to everyone found in peer
  discovery.
• History-Based After peer discovery, choose at
  most one peer to send to per discovery period
  the one with best past history of delivering data
  to base.
• Compared to direct no peer-to-peer, just to
  base
• Success rate metric Of all data produced in a
  month, what fraction was delivered to the base
  station?

15
Experimental Results

• Used their own ZNetSim simulator to vary
  parameters and determine best solution
• These graphs show the difference between direct
  connections and peer-to-peer multihop

16
Experimental Results (cont)
Direct Connection proves to be the least reliable
type of connection
17
Experimental Results (cont)

• Radio range key to data
• homing success 3-4km for 50 collars in
  20kmx20km area
• Success rate
• Ideal flooding best
• Constrained bandwidth history best
• Energy trends make selective protocols best
• Mobility model key to protocol evaluations
• Fast random moves hurt history
• Chicken and Egg
• mobility model is the biology research goal

18
Future Plans

• Hardware
• Nov 02 waterproof prototype for local animal
  tests
• Spring 03 build final rugged version
• Software
• Impala middleware
• Allow for wireless software updates adaptivity
• Beyond wildlife tracking
• Resource recovery, traffic management, security,
  surveillance

19
Conclusions

• ZebraNet as Engineering Research
• Early detailed look at mobile sensor net with
  mobile base stations
• Demonstrates promise of large-extent, long-life
  sensor networks with GPS
• Detailed look at power/energy concerns
• ZebraNet as Biology Research
• Enabling technology for long-range migration
  research
• Good view of key inter-species interactions

20
Discussion Questions???

• Does this model what they want?
• Is this really scalable to other situations?
• What other animals could be fitted with these
  sensors?