| We consider the transceiver design for uplink multiuser multi-input multi-output (MIMO) communications, where multiple transmitters adopt beamforming to simultaneously access the linear spatial equalizer at the receivers. In this paper, we investigated the crucial, yet not well discussed issue to jointly design beamforming weights for all transmitters, subject to total transmission power constraints, under the assumption that all users’ channel state information (CSI) is available at each of the users. It is worthy to emphasize that this is a different issue from the uplink multiuser receiving beamforming design, where the beamforming, instead of spatial equalization, is performed at the receiver and the transmitters are usually assumed to have just single antenna. We proposed a class of orthogonal joint beamforming design schemes with matched filter receiver, and an eigen-beamforming scheme with ordered serial interference cancellation minimum mean square error receiver (OSIC-MMSE). By comparing these schemes with the optimal joint transceiver design proposed by Yener, we show that eigen-beamforming with OSIC-MMSE achieves near-optimum performance at much lower complexity and with much simpler transmitter design, since it only requires each transmitter to know its own CSI and thus can be implemented in a decentralized way. This indicates that marginal performance improvement can be benefited from making all transmitters share their CSI. The orthogonal beamforming schemes, on the other hand, achieve the simplest receiver structure at the cost of more complicated cooperative transmitters, and they may find applications in such systems as satellite communications or Ad-hoc networks, where it is better to distribute computational loads among multiple transmitters than to impose it on a single receiver. |
| (1)Songnan Xi received the B.S. and M.S. degrees in wireless communications from Beijing University of Posts and Telecommunications, Beijing, P.R. China in 2001 and 2004 respectively. After graduation, she worked as a system engineer in the R&D Center, SIEMENS Ltd. China. She is currently working toward the Ph.D. degree in electrical engineering in Purdue University, Indiana. Her research interests are in the area of wireless communications and signal processing.
(2)Michael D. Zoltowski (F’98) was born in Philadelphia, PA, on August 12, 1960. He received both the B.S. and M.S. degrees in electrical engineering with highest honors from Drexel University, Philadelphia, PA, in 1983, and the Ph.D. degree in systems engineering from the University of Pennsylvania, Philadelphia, in 1986.
From 1982 to 1986, he was an Office of Naval Research Graduate Fellow. During 1987, he was a Summer Faculty Research Fellow at the Naval Ocean Systems Center, San Diego, CA. In Fall 1986, he joined the faculty of Purdue University, West Lafayette, IN, where he currently holds the position of Professor of Electrical and Computer Engineering. He has served as a consultant to several companies in the telecommunications industry.
His present research interests include space–time adaptive processing for all areas of mobile and wireless communications, GPS, and radar.
Dr. Zoltowski has served as an Associate Editor for both the IEEE TRANSACTIONS ON SIGNAL PROCESSING and the IEEE COMMUNICATIONS LETTERS. He currently serves as an Area Editor in charge of feature articles for the IEEE Signal Processing Magazine. |