Experiences and Challenges in Campaign Style Deployments using Wireless Sensor Networks

1. Experiences and Challenges in Campaign Style Deployments using 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*

2. Campaign Style Deployment Quito Jayant Gupchup

3. Requirements / Constraints Jayant Gupchup • 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

4. A Typical Sensor Network Stable Storage Gateway/ Basestation ……. 7 Ah

5. Differences / Challenges Power ~ 4W Jayant Gupchup • 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

6. Deployment Details - I Jayant Gupchup • Location : Quito, Ecuador • Goal : Understand tropical soil respiration • Duration : 16 days

7. Deployment Details -II Jayant Gupchup • 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

8. A CO2 Set-Up 3 m 3 m 3 m Jayant Gupchup

9. Under The Hood Antenna TelosB Mote Mote Battery CO2 Sensor Power Connector CO2 Sensors Jayant Gupchup

10. Power Consumption Jayant Gupchup • Lead acid car batteries 12V / 45Ah • Each battery serviced 9 CO2 sensors • Total current draw :1A • Lasted 36 hours after recharge

11. Power Cycling Motivation 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

12. Some Data Power Loss Sensors lack range Jayant Gupchup

13. Ad Hoc Replacements Jayant Gupchup • 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)

14. High Data Rates Jayant Gupchup • 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

15. System Performance Automated parts from existing system worked well. Jayant Gupchup

16. Conclusions Jayant Gupchup • 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

17. Credit Jayant Gupchup NSF- MIRTHE, NSF- IDBR Microsoft Research Betty and Gordon Moore Foundation

18. Questions Jayant Gupchup