Underwater Sensor Networks: Random Access and Compressive Sensing

Professor Milica Stojanovic
Northeastern University

Wednesday, April 27, 2011 - 10:00am - 12:00pm

CoRE Auditorium

"Underwater Sensor Networks: Random Access and Compressive Sensing" by M. Stojanovic, Northeastern University

Wireless information transmission through the ocean is one of the enabling technologies for the development of future ocean-observation systems, whose applications range from oil industry to aquaculture and include gathering of oceanographic data, pollution control, climate recording, and transmission of images from remote sites. Underwater wireless communications are usually established using acoustic waves, since electro-magnetic waves propagate only over very short distances. However, acoustic communications are limited by three factors: low bandwidth, low speed of sound, and poor quality of the physical link. These constraints yield a difficult communication channel, while additional, system-level constraints come from the limited battery supply (re-charging is difficult underwater) and the half-duplex operation of existing acoustic modems. For networks that are deployed for long-term monitoring of environmental phenomena, it is crucial to design an efficient data gathering scheme that prolongs the system’s life-time. To this end, we exploit the sparse nature of the monitored field and design a random access / compressive sensing (RACS) scheme in which the sensors transmit at random to a fusion center which then reconstructs the field. We provide an analytical framework for system design that captures packet collisions due to random access, as well as packet errors due to communication noise. Through analysis and examples, we demonstrate that recovery of the field can be attained using only a fraction of the resources (energy per bit, bandwidth) used by a conventional TDMA network, while employing a scheme that is simple to implement, requires no synchronization or scheduling, and no downlink feedback.

Milica Stojanovic graduated from the University of Belgrade, Serbia, in 1988, and received the M.S. and Ph.D. degrees in electrical engineering from Northeastern University, Boston, MA, in 1991 and 1993. After a number of years with the Massachusetts Institute of Technology, where she was a Principal Scientist, she joined the faculty of Electrical and Computer Engineering Department at Northeastern University in 2008. She is also a Guest Investigator at the Woods Hole Oceanographic Institution, and a Visiting Scientist at MIT. Her research interests include digital communications theory, statistical signal processing and wireless networks, and their applications to underwater acoustic communication systems. Milica is a Fellow of the IEEE and serves as an Associate Editor for the IEEE Journal of Oceanic Engineering and the IEEE Transactions on Signal processing.

Link to Dr. Stojanovic's presentation slides.