IEEE Gainesville Section and Department of Electrical and Computer Engineering presents Downlink Transmit Beamforming for Multi-User MIMO Systems Lee Swindlehurst, Professor Brigham Young University Electrical and Computer Engineering Monday, January 29, 2007 3:00 – 3:50 pm in Room 201 of the New Engineering Building #33, Center Drive, University of Florida Abstract Downlink beamforming refers to the problem of using an array of antennas at a particular node (e.g., a base station) in a wireless network to communicate simultaneously with multiple co-channel users. The users in the network may have a single antenna, and hence no ability for spatial discrimination, or they may have multiple antennas and the ability to perform some type of interference suppression. The primary issue is how to balance the need for high received signal power for each user against the interference produced by the signal at other points in the network. In this presentation, we describe several approaches to this problem: channel inversion, regularized channel inversion, channel block diagonalization, coordinated transmit/receive beamforming, and vector precoding. While the basic idea behind these algorithms is the same, namely the use of channel information at the transmitter to predict and then counteract the interference produced at each node in the network, each of the algorithms is based on achieving a different performance objective. Typical performance criteria include zero-interference transmission, minimum transmit power subject to a minimum signal-to-interference plus noise ratio at each receiver, or maximum throughput subject to a given transmit power constraint. We compare the various goals of the above algorithms, and detail their respective advantages and disadvantages in terms of computational complexity, required transmit power, network throughput, and assumed receiver capabilities. Biography Dr. Swindlehurst received the B.S., summa cum laude, and M.S. degrees in Electrical Engineering from Brigham Young University, Provo, Utah, in 1985 and 1986, respectively, and the Ph.D. degree in Electrical Engineering from Stanford University in 1991. From 1986-1990, he was employed at ESL, Inc., of Sunnyvale, California, where he was involved in the design of algorithms and architectures for several radar and sonar signal processing systems. He joined the faculty of the Department of Electrical and Computer Engineering at Brigham Young University in 1990, where he holds the position of Full Professor and is currently serving as department chair. During 1996-1997, he held a joint appointment as a visiting scholar at both Uppsala University, Uppsala, Sweden, and at the Royal Institute of Technology, Stockholm, Sweden. His research interests include sensor array signal processing for radar and wireless communications, detection and estimation theory, and system identification, and he has 150 publications in these areas. Dr. Swindlehurst is a Fellow of the IEEE and a past Secretary of the IEEE Signal Processing Society. He is currently serving as a member of the Editorial Board for the EURASIP Journal on Wireless Communications and Networking and the IEEE Signal Processing Magazine, and is a past Associate Editor for the IEEE Transactions on Signal Processing. He is a recipient of several paper awards: the 2000 IEEE W. R. G. Baker Prize Paper Award, the 2006 IEEE Signal Processing Society's Best Paper Award, the 2006 IEEE Communications Society Stephen O. Rice Prize in the Field of Communication Theory, and is co-author of a paper that received the IEEE Signal Processing Society Young Author Best Paper Award in 2001. If you need further information, please contact Prof. Jian Li li@dsp.ufl.edu 392-2642