Events

 
Seminar
On the Capacity of Triply Selective MIMO Fading Channels

by Dr. Chengshan Xiao, University of Missouri-Columbia, Missouri, USA.

Date
 :  27 May 2005 (Fri)
Time
 :  11:00am - 12:00noon
Venue  :  Room 1403, 1/F (Lifts 25/-6), HKUST

Abstract
Multiple-Input Multiple-Output (MIMO) systems have emerged as a new paradigm in wireless communications due to their enormous capacity gains predicted by recent theoretical researches. However, the majority work of the MIMO channel capacity assumes that the MIMO fading channels are frequency flat and time quasi-static, that means the fading channels have neither intersymbol interference (ISI) nor Doppler spread, which is not the case in many practical wireless systems with high date rate and user mobility.

In this talk, we will consider realistic MIMO channels undergoing triply selective fading, that is, space-selective, time-selective and frequency-selective fading. We demonstrate that, besides spatial and temporal correlations, there exists ISI inter-tap correlations due to irregular delay spreads in frequency selective channels. This ISI inter-tap correlation has been largely overlooked but it has significant impact on channel capacity and transceiver design. We will present both theoretical and simulation results for the ergodic capacity and outage capacity of MIMO triply selective fading channels. Our results show that (1) the frequency selective channel usually have smaller ergodic capacity that frequency flat channel, which is different from the established results in the literature; (2) although time variation has no influence on ergodic capacity, it has significant impact on the outage capacity; (3) MIMO channels have four-dimensional diversities which consist of transmit, receive, Doppler and multipath diversities.


Biography
Chengshan Xiao received the B.S. degree from the University of Electronic Science and Technology of China, Chengdu, China, in 1987, the M.S. degree from Tsinghua University, Beijing, China, in 1989, and Ph.D. degree from the University of Sydney, Australia, in 1997, all in electrical engineering.

Dr. Xiao was a lecturer at Tsinghua University, Beijing, China, a Senior Member of Scientific Staff at Nortel Networks at Ottawa, Canada, and an Assistant Professor at the University of Alberta, Canada. He is currently a faculty member at the University of Missouri-Columbia, Missouri, USA. Dr. Xiao's research interests include wireless communication networks, signal processing, multidimensional and multirate systems, and nonlinear control. He has published more than 80 papers in international journals and conferences. He holds 3 US patents in wireless communications area. Two of his algorithms have been implemented into Nortel's base station radios with successful technical field trials and network integration.

Dr. Xiao is an Associate Editor for IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, and IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY. Previously, he was an Associate Editor for IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS-I, and INTERNATIONAL JOURNAL OF MULTIDIMENSIONAL SYSTEMS AND SIGNAL PROCESSING. He is the Vice Chair of Technical Committee on Personal Communications of IEEE Communication Society.

 

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