10/18/2004 NSF-NOSS PI meeting 1 Sensor Networks for Undersea Seismic Experimentation (SNUSE) PI: John Heidemann Co-PIs: Wei Ye, Jack Wills Information Sciences Institute University of Southern California

210/18/2004NSF-NOSS PI meeting Why Undersea Sensor Networks? Vision: to reveal previously unobservable phenomena (Pottie) Goal: to expand senor-net technology to undersea applications Numerous potential applications Oilfields: seismic imaging of reservoir Oilfields: seismic imaging of reservoir Environmental: pollution monitoring Environmental: pollution monitoring Biology: fish or micro-organism tracking Biology: fish or micro-organism tracking Geology: undersea earthquake study Geology: undersea earthquake study Military: undersea surveillance Military: undersea surveillance

310/18/2004NSF-NOSS PI meeting Our Focus Application Collaborate with USC’s ChevronTexaco Center for Interactive Smart Oilfield Technologies (CiSoft) Collaborate with USC’s ChevronTexaco Center for Interactive Smart Oilfield Technologies (CiSoft) Current technology High cost High cost Perform rarely, about once every 1-3 years Perform rarely, about once every 1-3 years Photo courtesy Institute of Petroleum Seismic imaging for undersea oilfields Seismic imaging for undersea oilfields

410/18/2004NSF-NOSS PI meeting Buoys Radio Buoys Our Approach: Undersea Sensor Nets Dense sensor networks are largely changing terrestrial sensing today Bring the concept to undersea environment Enable low-cost, frequent operation Enable low-cost, frequent operation Exploit dense sensors, close observation Exploit dense sensors, close observation Platform Acoustic

510/18/2004NSF-NOSS PI meeting Current Undersea Networking Sparse networks, small number of nodes, long- range acoustic communication Navy Spawar (Rice): Seaweb network ~20 nodes Navy Spawar (Rice): Seaweb network ~20 nodes Woods hole & MIT (Stojanovic) Woods hole & MIT (Stojanovic) Northeastern Univ. (Proakis) Northeastern Univ. (Proakis) Navy Postgraduate School (Xie) Navy Postgraduate School (Xie) Cable networks: high speed, high cost Neptune Network (Several Universities led by Univ. of Washington) Neptune Network (Several Universities led by Univ. of Washington) 3000km fiber-optic/power cables; $250 million in 5 years 3000km fiber-optic/power cables; $250 million in 5 years Instead we focus on low-cost, wireless and dense networks

610/18/2004NSF-NOSS PI meeting Can We Use Current Land Sensor Nets? Radios don’t directly apply Water significantly absorbs radio waves Water significantly absorbs radio waves Mica2’s Tx range is ~50cm in water (Sukhatme) Can we simply replace radio with acoustic communication? Large propagation delay breaks/degrades many protocols Large propagation delay breaks/degrades many protocols Propagating 200m needs 133ms(1500m/s) Propagating 200m needs 133ms(1500m/s) Need acoustic communication and new networking protocols

710/18/2004NSF-NOSS PI meeting Acoustic Comm.: Challenges Acoustic channel is complex High environmental noise and multi-path fading High environmental noise and multi-path fading Low bandwidth Low bandwidth Transmission curvature caused by uneven temperature distribution – shadow area Transmission curvature caused by uneven temperature distribution – shadow area Low-power transducers/hydrophones Existing work Focus on reliability and bandwidth utilization (push to higher bit rates) Focus on reliability and bandwidth utilization (push to higher bit rates) COTS acoustic modems are long range (1-90km), power hungry and costly COTS acoustic modems are long range (1-90km), power hungry and costly

810/18/2004NSF-NOSS PI meeting Acoustic Comm.: Our Approach Develop hardware for short-range communication (50—500m) short-range communication (50—500m) Low-power operation (similar to Mica2 radio) Low-power operation (similar to Mica2 radio) Low data rate (10kbps) Low data rate (≤10kbps) Will take existing results from acoustic communication research Modulation, coding, reliable transmission, etc. Modulation, coding, reliable transmission, etc. Short range largely avoids complex channel problems and is the key for low power hardware

910/18/2004NSF-NOSS PI meeting Networking Protocols: Challenges Large and varying propagation delay Sound is over 5 magnitude slower than radio Sound is over 5 magnitude slower than radio Sound speed changes with temperature, depth and salinity Sound speed changes with temperature, depth and salinity How does it affect existing protocols? Time sync will break as they all ignores radio propagation delay Time sync will break as they all ignores radio propagation delay Fine-grained localization will break as they all depends on radio signal to sync node pairs Fine-grained localization will break as they all depends on radio signal to sync node pairs TDMA needs time sync, and contention MAC could have bad performance TDMA needs time sync, and contention MAC could have bad performance

1010/18/2004NSF-NOSS PI meeting Networking Protocols: Our Approach New time-sync and localization algorithms Estimating the propagation delay is the key for high-precision time synchronization Estimating the propagation delay is the key for high-precision time synchronization Combine localization with time sync Combine localization with time sync MAC protocols suitable for large propagation delay Quantify performance loss with high delay Quantify performance loss with high delay Re-design efficient MACs in high latency networks Re-design efficient MACs in high latency networks

1110/18/2004NSF-NOSS PI meeting Long-Term Energy Management Application only runs once a month Nodes sleep for a month to conserve energy Nodes sleep for a month to conserve energy Will investigate new energy management schemes for long sleep time Will investigate new energy management schemes for long sleep time Inspired by work at Intel Portland Delay tolerant data transport Large sensor data when application runs Large sensor data when application runs 6MB in 5 minutes with 20kHz sampling rate Low-bandwidth acoustic comm. (~10kbps) Low-bandwidth acoustic comm. (~10kbps) Will investigate suitable DTN techniques Will investigate suitable DTN techniques Delay tolerant networking research group (dtnrg.org)

1210/18/2004NSF-NOSS PI meeting Summary Project goal: expanding sensor-network technology to undersea applications Research directions Hardware for low-power, short-range acoustic communications Hardware for low-power, short-range acoustic communications Networking protocols and algorithms suitable for long propagation delay Networking protocols and algorithms suitable for long propagation delay Long term energy management Long term energy management Project website