On the performance of multiuser MIMO systems in WCDMA/HSDPA: Beamforming, feedback and user diversity

Several multiple-input multiple-output (MIMO) techniques have been proposed for 3GPP WCDMA/HSDPA systems and several performance evaluation for the comparison purpose are in progress. Most MIMO candidates in HSDPA have been generally designed for point-to-point communication, which means that a single-user throughput is of their major concern. However, multiple users and user scheduling need to be considered in wireless packet transmission, so as to maximize system throughput. In this paper we propose an effective user scheduling technique in both space and time domains that offers three main benefits, which are the spatial-beamforming, uplink feedback signaling, and advanced receivers. Furthermore, user scheduling is combined with modified successive interference cancellation (SIC) reception, which allocates all transmit antennas to the best user with SIC or each transmit antenna to different users with minimum mean squared-error (MMSE). Simulation results show that the proposed scheme has higher user diversity gain than other MIMO candidates in terms of achievable throughput.