Experiences and Challenges in Campaign Style Deployments using Wireless Sensor Networks Jayant...
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Experiences and Challengesin Campaign Style Deploymentsusing Wireless Sensor Networks
Jayant Gupchup†, Scott Pitz*, Douglas Carlson† , Chih-Han Chang*, Michael Bernard*,
Andreas Terzis†, Alex Szalay±, Katalin Szlavecz*
Department of Computer Science, Johns Hopkins University†
Department of Physics and Astronomy, Johns Hopkins University±
Department of Earth and Planetary Sciences, Johns Hopkins University*
Campaign Style Deployment
205/05/23 Jayant Gupchup
Quito
Requirements / Constraints
• No access to line power or internet
• Collect data at a high rate (e.g. 30s)– Deployment order of days to weeks
• Researchers require access to data in field
305/05/23 Jayant Gupchup
A Typical Sensor Network
Gateway/Basestation
Stable Storage
…….7 Ah
Differences / Challenges
• On-site decisions
• Ad hoc hardware reconfigurations
• Dealing with high data rates in the field (using a netbook)
• Use of high power sensors– Vaisala CO2 sensors– Driven by a car battery
505/05/23 Jayant Gupchup
Power ~ 4W
Deployment Details - I
• Location : Quito, Ecuador
• Goal : Understand tropical soil respiration
• Duration : 16 days605/05/23 Jayant Gupchup
Deployment Details -II
• 30s Sampling Interval
• Data retrieved over the air using a netbook
• 20 Sampling locations– 12 Soil CO2– 8 Soil Temperature & Moisture
• Each CO2 Location– 3 depths (12 locations, 3 depths = 36 sensors)– Vaisala GMT 220 Series– CO2 Powered by 12 V / 45 Ah Car Battery
705/05/23 Jayant Gupchup
A CO2 Set-Up
805/05/23 Jayant Gupchup
3 m
3 m
3 m
Under The Hood
905/05/23 Jayant Gupchup
Antenna
TelosB Mote
CO2 Sensors
Mote Battery
CO2 SensorPower Connector
Power Consumption
• Lead acid car batteries 12V / 45Ah• Each battery serviced 9 CO2 sensors• Total current draw :1A • Lasted 36 hours after recharge
1005/05/23 Jayant Gupchup
Power Cycling Motivation
1105/05/23 Jayant Gupchup
• Batteries needed replacement/recharged every other day
• Carried every other day for ~ 3 Km
• 12V/40Ah car battery weighs 14Kg
• Power Cycling!– Warm up time: 15 min
Some Data
1205/05/23 Jayant Gupchup
Power Loss Sensors lack range
Ad Hoc Replacements
• At 11 locations, sensors lacked range to sense the phenomenon
• Distribution of CO2 hardware– 10000 ppm : 26– 20000 ppm : 12– 30000 ppm : 3– 100000 ppm : 3
• Researchers placed sensors initially– Reconfigured sensors if range was not good enough
• Final data calibration requires accurate metadata:– sensor type and date of reconfiguration
• Motivates need for self-Identifying sensors (Dallas 1-wire protocol)
1305/05/23 Jayant Gupchup
High Data Rates
• Decisions in field are driven by the data
• Researchers used netbook to download and view data
• 10 days of 30s sampling: ~ 576000 rows– Spreadsheet and word processing software unable to
handle this volume– Researchers stopped looking
• Downsample: Provide low-resolution “view” in the field
1405/05/23 Jayant Gupchup
System Performance
1505/05/23 Jayant Gupchup
Automated parts from existing system worked well.
Conclusions
• WSN technology is mature enough to be driven by scientists
• Challenges / Lessons Learned– Power cycling for high power sensors– Self-Identifying sensor design– Researchers require low-resolution data in field
1605/05/23 Jayant Gupchup
Credit
• NSF- MIRTHE, NSF- IDBR
• Microsoft Research
• Betty and Gordon Moore Foundation
1705/05/23 Jayant Gupchup
Questions
1805/05/23 Jayant Gupchup