EAGER: Networking on Underwater Acoustic MIMO Links

The highly-exposed live feed of the oil spill from underwater cameras in the Gulf of Mexico is one of many examples showcasing the importance of multimedia underwater sensor networks in fields such as underwater surveillance, undersea exploration, video-assisted navigation, and environmental monitoring. Multimedia networking, however, requires (i) much higher data rates than what has been available in the past with acoustic technology and (ii) flexible protocol design. Multiple-input-multiple-output (MIMO) is a transmission technique that may increase data rates or reduce link errors by leveraging the spatial diversity offered by the rich scattering structure of underwater acoustic propagation. To-date, little experimental data is available to the research community to assess the potential of MIMO gains in real underwater acoustic links. This project is an early-stage research effort to collect data and experimentally assess the potential of acoustic MIMO networking. A testbed is being built to measure and model the propagation characteristics of underwater MIMO links and understand how the fundamental MIMO multiplexing and diversity tradeoff translates into a tradeoff between achievable transmission rate and link error probability. The project identifies how the capabilities of MIMO links impact the design of higher layer networking protocols. The resulting characterization informs the design of a class of integrated medium access control and signaling techniques that optimally select the transmit power, MIMO transmission mode, and coding strength to improve data rates and reduce bit error rates. All collected data are being made available to the research community through the project website.