Joint Multiple Cell-Site Processing in Wyner-like Fading Models

Speaker: Shlomo Shamai
EE Dept, Technion, Haifa, IsraelAbstract: We investigate the information theoretic aspects of a simple cellular model, where users experience a soft-handoff situation under joint multicell decoding. The ultimate sum-rate limits of reliable communications in this model in non-fading and fading situations, are presented. Focus is put on the uplink in the high snr regime, with general fading statistics. In this case, adhering to a TDMA intra-cell protocol, a novel closed form expression for the per-cell sum-rate is developed. The result is based on study of the spectrum of certain large random Hermitian tri-diagonal Jacobi matrices. Specifically, since the matrices of interest are tridiagonal, their eigenvectors can be considered as sequences with second order linear recurrence. Therefore, the problem is reduced to the study of the exponential growth of products of two by two matrices. For the case where K users are simultaneously active in each cell, we obtain a series of lower and upper bounds on the high-SNR power offset of the per-cell sum-rate, which are considerably tighter than previously known bounds. The technique can be adapted to generalized Wyner-like cellular models. We examine also special cases of zero/one dependent (per user) `fading` structures to analyze in the impact of users' activity in a `soft handoff` Wyner model. In this case close form expressions are developed for respective capacities in the outage regime, addressing also ergodic case. Time permitting, duality principles that relate the uplink performance to the downlink are discussed, mentioning the results for unfaded and faded cases, and pointing out some open problems.Biography: Shlomo Shamai (Shitz) (S'80–M'82–SM'89–F'94) received the B.Sc., M.Sc., and Ph.D. degrees in electrical engineering from the Technion—Israel Institute of Technology, in 1975, 1981 and 1986 respectively. During 1975-1985 he was with the Communications Research Labs in the capacity of a Senior Research Engineer. Since 1986 he is with the Department of Electrical Engineering, Technion—Israel Institute of Technology, where he is now the William Fondiller Professor of Telecommunications. His research interests encompass a wide spectrum of topics in information theory and statistical communications. He is especially interested in theoretical limits in communication with practical constraints, multi-user information theory and spread spectrum systems, multiple-input-multiple-output communications systems, information theoretic models for wireless networks and systems, information theoretic aspects of magnetic recording, channel coding, combined modulation and coding, turbo codes and LDPC, in channel, source, and combined source-channel applications, iterative detection and decoding algorithms, coherent and noncoherent detection and information theoretic aspects of digital communication in optical channels. Dr. Shamai (Shitz) is a member of the Union Radio Scientifique Internationale (URSI). He is the recipient of the 1999 van der Pol Gold Medal of URSI, and a co-recipient of the 2000 IEEE Donald G. Fink Prize Paper Award, the 2003, and the 2004 Joint IT/COM Societies Paper Award, and the 2007 Information Theory Society Paper Award. He is also the recipient of the 1985 Alon Grant for distinguished young scientists and the 2000 Technion Henry Taub Prize for Excellence in Research. He has served as Associate Editor for the Shannon Theory of the IEEE Transactions on Information Theory, and also serves on the Board of Governors of the Information Theory Society.Host: Giuseppe Caire, caire@usc.edu, EEB 528, x07326

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Gerrielyn Ramos