"Sequence Estimation for Degraded Channels Via the EM Algorithm"

Prof. Costas N. Georghiades
Texas A&M University

Friday, May 7th, 2:00 PM, ENS 302

georghia@ee.tamu.edu

Abstract

It is well known that maximum-likelihood sequence estimation (MLSE) for channels perturbed by random (or simply unwanted) parameters is computationally hard to obtain. This is so either because deriving the likelihood function is analytically intractable, or, in cases when the latter is possible, because of the unavailability of efficient ways to evaluate it, and the resulting exponential number of evaluations as the sequence length increases. In these cases, a formulation of the MLSE problem using the expectation-maximization (EM) algorithm often results in a performance which is close to the optimum, at a complexity which is linear in the sequence length instead of exponential. The talk will first introduce the EM algorithm, and then apply it to a number of channels of practical interest, including the fading channel and the interference channel.

Biography

Costas N. Georghiades received the B.E. degree with distinction from the American University of Beirut in June 1980, and the M.S. and D.Sc. degrees from Washington University in May 1983 and May 1985 respectively, all in Electrical Engineering. Since September 1985 he has been with the Electrical Engineering department at Texas A&M University, where he is a Professor and holder of the J.W. Runyon, Jr. Endowed Professorship. He currently serves as Director of the Telecommunications and Signal Processing Group, and as co-Director of the VLSI-Telecommunications Research Center (VTRC). His general interests are in the application of information, communication and estimation theories to the study of communication systems, with specific interest in optimum receiver design, mobile radio, spread-spectrum, multicarrier modulation, and synchronization systems. Dr. Georghiades is a Fellow of the IEEE, a member of Sigma Xi and Eta Kappa Nu, and a registered Professional Engineer in Texas. He served as an Editor of the IEEE Transactions on Communications, as Publications Editor for the IEEE Transactions on Information Theory, as Guest-Editor for the IEEE Journal on Selected Areas in Communications, as an Associate Editor of the IEEE Transactions on Information Theory, and as Associate Editor for the IEEE Communication Letters. He has been involved in organizing a number of conferences, and currently serves as the Technical Program Chairman for the 1999 IEEE Vehicular Technology Conference.

A list of Signal and Image Processing Seminars is available at from the ECE department Web pages under "Seminars". The Web address for the Signal and Image Processing Seminars is http://anchovy.ece.utexas.edu/seminars