Abstract:

In wireless ad hoc networks that do not employ code-division multiple access, medium access control (MAC) protocols are used to allocate the channel to specific transmitters and receivers, typically to the exclusion of all other users within the interference ranges of the transmitters and receivers.  A few authors have proposed the use of multiuser detection (MUD) or dirty paper coding (DPC) to allow transmissions in an ad hoc network to occur simultaneously, even when the transmissions cause to each other.  However, such proposals usually assume that the MUD or interference cancellation (IC) schemes can completely excise the interference without knowing the interfering signals.

In this presentation, we consider a more practical approach in which multiple transmissions are allowed only when the information in the interfering signal is known at the receiver and thus simpler MUD schemes can be applied. This may often occur in ad hoc networks because multi-hop routing causes the information that was transmitted by a node to be transmitted later by one of that node’s neighbors. We call this approach overlapped transmission. The restriction that the interference is known places some limits on when the MUD techniques can be applied. We investigate these limits for random networks with non-fading channels. We then propose a simple protocol for scheduling overlapped transmissions and investigate its performance.

Biography:

John M. Shea (S'92-M'99) received the B.S. (with highest honors) in Computer Engineering from Clemson University in 1993 and the M.S. and Ph. D. degrees in electrical engineering from Clemson University in 1995 and 1998, respectively.   Dr. Shea is currently an Associate Professor of electrical and computer engineering at the University of Florida.  Prior to that, he was an Assistant Professor at the University of Florida from July 1999 to August 2005 and a post-doctoral research fellow at Clemson University from January 1999 to August 1999. He is currently engaged in research on wireless communications with emphasis on error-control coding, cross-layer protocol design, cooperative diversity techniques, and hybrid ARQ.   Dr. Shea was selected as a Finalist for the 2004 Eta Kappa Nu Outstanding Young Electrical Engineer Award.  He received the Ellersick Award from the IEEE Communications Society in 1996.  Dr. Shea was a National Science Foundation Fellow from 1994 to 1998.  He is an Associate Editor for the IEEE Transactions on Vehicular Technology.