Abstract

Underwater Acoustic Sensor Networks are used for the exploration of natural undersea resources, collection of oceanographic data, pollution monitoring, offshore exploration, disaster prevention, assisted navigation and tactical surveillance. Utilizing acoustic communications, sensor nodes gather and send data to sink nodes. Employing radio communications, the sinks forward the data to other surface located nodes or satellites. The Internet type of communication protocols work solely for sink nodes with classical wireless access. Specific protocols are required for submerged node communications.

In this talk, I will address protocol design for long range underwater/under ice acoustic communications. In the present state of scientific and technical progress, long range underwater communications are more likely to be achievable at low frequency and narrow bandwidth. We concentrate on low frequency mobile acoustic communications in the 300 Hz to 3 kHz range. Because of the narrow half-power bandwidth at low frequency and long distance, solely extremely low data rates are possible. At low data rates, the Doppler effect is also a difficult problem. My research draws on the science of extremely weak signal communications that can deal with channels with 250 dB attenuation or more. I will focus on the design of a data link layer protocol, which includes framing and high redundancy Forward Error Correction. The complexity is in the receiver. Algebraic and probabilistic decoding techniques are combined to determine what is most likely the content of a message. Performance results obtained through simulation and sea trials will be discussed.

Bio

Michel Barbeau is a professor of Computer Science. He got a Bachelor (Universite de Sherbrooke, Canada ’85), a Master’s and a Ph.D., in Computer Science (Universite de Montreal, Canada ’87 & ’91). From ’91 to ’99, he was a professor at Universite de Sherbrooke. During the ’98-’99 academic year, he was a visiting researcher at the University of Aizu, Japan. Since 2000, he works at Carleton University, School of Computer Science, Canada. His current research interests are wide area ad hoc networks, underwater communications and networks, quantum communications and networks.