DESCRIPTION/ABSTRACT: Markov chains and Markov processes are natural models for various communication channels in which channel conditions change with time. In many cases it is not the state sequence of the model which is observed but the effects of the process on a signal. That is, the states are not observable but some functions, possibly random, of the states are observed. In some cases it is easy to assign the values of the parameters to model a channel. All that remains is to determine what probabilities are desired and derive the necessary algorithms to compute them. In other cases, the choice of parameter values is only an estimate and it is desired to find the "best" values. The usual criterion is maximum likelihood. That is: find the values of parameters which maximize the probability of the observed data. This is the problem that is addressed by the Baum-Welch computation.

SPEAKER BIO: Dr. Welch received his B.S. degree in Mathematics from the University of Illinois in 1951 and his Ph.D. for the California Institute of Technology in 1958. He joined the Jet Propulsion Laboratory in 1956 as a methematician and in 1959 worked for the Communications Research Division of the Institue for Defense Analyses in Princeton, New Jersey. He was visisting Associate Professor in the Department of Electrical Engineering at the University of Southern California from 1965-1968, then held the position of Professor until his retirement in 1999. Dr. Welch is a member of the National Academy of Engineering, and IEEE Fellow and the recipient of the 2003 Claude E. Shannon Award from the IEEE Information Theory Society.

MORE INFORMATION: The second annual Shannon Memorial Lecture at UCSD will be presented by Lloyd R. Welch, Professor Emeritus in the Electrical Engineering Department of the University of Southern California. The event is organized by the Center for Magnetic Recording Research (http://cmrr.ucsd.edu), and co-sponsored by Calit2 and the Jacobs School of Engineering. The talk will also be streamed simultaneously over the Internet.
To watch the live webcast, go to http://earth.ucsd.edu:8080/ramgen/encoder/welch.rm.

Shortly after the lecture, it will be available for on-demand viewing from the multimedia archive at http://www.calit2.net/multimedia/index.html. [RealOne Player or Realplayer required]