CitySenseA Vision for an Urban-ScaleSensor Network Testbed

Josh Bers†, Matt Welsh*, and Majid Ezzati‡† BBN Technologies, Inc.

* School of Engineering and Applied Sciences, Harvard University

‡ School of Public Health, Harvard University

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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GoalsSupport experimentation with wireless sensor networks at

scale– Simulations are valuable but inherently limited– Understanding characteristics of real sensor networks in diverse

environments requires real testbeds and real applications– Testbeds should be open and easily shared by multiple research

groups

Build a programmable testbed that supports– Wireless sensor research– Wireless networking research– Interface with larger GENI effort

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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CitySense TestbedDeploy outdoor testbed of 100 embedded PCs across a city

– Currently in negotiation with Cambridge, MA.– Linux-based embedded PCs with meteorological and air quality sensors– 802.11a/b/g interface with multihop wireless networking backbone: Use

existing open-source standard: OLSR, HSLS

Current Status – Project began in Sept. 2006.– Have a 15 node dual-radio prototype testbed running at BBN and Harvard: 8

outdoor and 7 indoor nodes– 3 outdoor nodes continuously gathering weather sensor data (http://

citysense.bbn.com/LiveMonitor/)– Time synchronization between nodes using NTP– Remote synchronization of baseline software over the air.

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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CitySense Overview

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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CitySense Node DesignSoekris net4826 embedded PC running Linux256 MB of RAM+flash, 1 GB USB flash driveTwo 802.11 radios b/g & 900 MHz, w/8 & 6 dBi omni antennasVarious sensors driven by app requirements

– Vaisala Weather Sensor (temp, humidity, pressure, wind, rain, ...)

– *Gas sensors (CO2, CO, O3...) – *Air particulate sensor (PM10

for air quality studies)– Microphones? Cameras?

Photocell (Power)

CitySense Node goes here

Photocell (Power)

CitySense Node goes here

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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BBN Network Topology

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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Cross-discipline Research Enabled

Sensor Networking– Spatio-temporal data fusion [Akyildiz ’04]– Distributed query processing / data routing [Sung ’07]

Wireless Networking (GENI)– Mesh routing protocols: geographic routing, Dynamic

RF channel selection– Disruption Tolerant Networks (DTN)

Urban Monitoring– Public health studies: air pollution– Homeland security: bio-chem, toxic gas release

tracking– Environmental impact: building efficiency, wind tunnel

effects

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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Testbed ChallengesResource management and sharing

– How to support many applications? Fairness? Security? Sandboxing?

Programming models and languages– What is the right programming abstraction for a city-wide sensor

network? ssh into every node? SQL? Something in between?

Robustness and administration– How to administer and maintain a network of 100+ nodes over a

wireless mesh, without physical access?– Separate management/control radio

City Political Hurdles– Press coverage / City politics– Public acceptance / privacy issues– Benefits to City: K-12 summer workshop, using data to support

green initiatives, commercial location based services..

© 2007 BBN Technologies © 2007 Matt Welsh – Harvard University

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Acknowledgements / Questions?

CitySense team:– Abhimanyu Gosain (Tufts grad student), Bob

Keyes, Geoff Mainland, Rohan Murty (Harvard grad students), Jon Hyman, Matt Tierney (Harvard undergrads)

For more information:– Josh Bers (jbers@bbn.com) and Matt Welsh (

mdw@eecs.harvard.edu)– http://www.citysense.net