APPLIED MATH SEMINAR

Speaker: Edmund Yeh, Electrical Engineering, Yale University

Title: Polar Codes for Multiple Access Channels

When/where: Tuesday, November 9th, 4:15 PM, AKW 200

Abstract:

Achieving the fundamental capacity limits of communication channels with low complexity coding schemes has been a major challenge for over 60 years.  Recently, a revolutionary coding construction, called polar coding, has been shown to provably achieve the capacity of discrete memoryless single-user channels.  The underlying principle of the technique is to convert repeated uses of a given single-user channel to single uses of a set of extremal channels, whereby almost every channel in the set is either almost perfect, or almost useless.  The latter phenomenon is referred to as polarization.

Whereas a number of practical coding constructions (e.g. Turbo codes and Low Density Parity Check codes) can empirically approach the capacity of single-user communication channels, there is still a shortage of good practical coding schemes for multi-user communication channels.  In this talk, we extend the polar coding method to two-user multiple-access communication channels. We show that if the two users use the channel combining and splitting construction, the resulting multiple-access channels will polarize to one of five possible extremals, on each of which uncoded transmission is optimal.  Our coding technique can achieve some of the optimal transmission rate pairs obtained with uniformly distributed inputs.  The encoding and decoding complexity of the code is O(n log n) with n being the block length, and the block error probability is roughly O(2^{-\sqrt{n}}).  Our coding construction is one of the first low-complexity coding schemes which have been proved to achieve capacity in multi-user communication networks.

Joint work with Eren Sasoglu and Emre Telatar

Biography:

Edmund Yeh received his B.S. in Electrical Engineering with Distinction from Stanford University in 1994, his M.Phil in Engineering from the University of Cambridge in 1995, and his Ph.D. in Electrical Engineering and Computer Science from MIT in 2001.  Since 2001, he has been on the faculty at Yale University, where he is currently an Associate Professor of Electrical Engineering, Computer Science, and Statistics.

Professor Yeh is the recipient of a Humboldt Research Fellowship, an Army Research Office Young Investigator Award, the National Science Foundation and Office of Naval Research Graduate Fellowships, the Winston Churchill and Barry Goldwater Scholarships.  He is a member of Phi Beta Kappa and Tau Beta Pi.