Energy-Efficient Computing for Wildlife Tracking Design Tradeoffs and Early Experiences with ZebraNet Created by Chris Roedel Presented by Israel Martinez

Some Graphics Courtesy of Princeton University ZebraNet Project Overview Background Information Other Sensor Networks ZebraNet Design Goals Life as a Zebra Collar Design Protocol Design Experimental Results Discussion Questions 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Why Other Networks Won’t 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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project Contributions 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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project 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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project Zebra Movement Speeds From Field Data Grazing: 0.017m/s Graze-walking: 0.072 m/s Fast: 0.155 m/s Turns ~ < 60° 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Power and Weight Information Idle <1 mA GPS Position Sampling & CPU / Storage 177 mA Base Discovery only 432 mA Transmit Data to Base 1622 mA GPS chip + CPU 8 grams Short-range Radio 20 grams Long-range Radio and packet modem 296 grams Rechargeable Batteries 287 grams Solar Cell Array 540 grams Total 1151 grams Total Weight Goal 3-5 lbs. Energy Goal: 5 days if no recharge 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Basic Protocol in Action Harem A A,B Harem A and Harem B come within short range radio range. They transfer their own information with each other Harem B B,A 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

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 B’s and A’s information to C. Harem C transfers its information to B. Harem C C Harem A A,B Harem B B,A 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

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 B’s and A’s. The base station has the information from all the animals even though it only came within range of Harem C. Harem C C,B,A Harem B B,C,A 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project 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? 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project ZNetSim It’s a zebra mobility model and simulation environment for ZebraNet It was armed with facts and field observation about zebra behavior and reasonable assumptions of the terrain and operating characteristics of the Mpala Research Center in Kenya It returns two metrics: Success rate – the percentage of data that gets back to the base station Energy consumption 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project 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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Experimental Results (cont) Direct Connection proves to be the least reliable type of connection 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Experimental Results (cont) 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project 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… 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project 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 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project

Some Graphics Courtesy of Princeton University ZebraNet Project Discussion Questions? Does this model what they want? What other animals could be fitted with these sensors? 12/4/2018 Some Graphics Courtesy of Princeton University ZebraNet Project