User and Transmit Antenna Selection for MIMO Broadcast Wireless Channels with Linear Receivers

This paper considers a signalling scheme for a multi-user wireless broadcast system where the base station has multiple transmit antennas and users can have multiple receive antennas. Independent data streams are transmitted in this system by allocating different transmit antennas to different selected users where multiple transmit antennas may be allocated to each selected user. The signalling scheme is used to select the particular users to receive data in a transmission block and to allocate transmit antennas to those users. We examine two partial feedback schemes for selecting users: one that we call norm-based and the other that we call SINR-based. We also present a novel transmit-antenna selection scheme for allocating multiple transmit antennas to selected users based on the Gram-Schmidt orthogonalisation algorithm. The signalling scheme presented in this paper reduces the amount of channel information required by the base station. We study the performance of the user selection and transmit-antenna selection schemes when linear receivers are used at the receiver side for decoding the transmitted signal. In particular, we consider zero-forcing (ZF) and minimum mean square-error (MMSE) receivers. We examine the sum capacity performance of the system compared to schemes with no feedback and using random antenna selection. We show that the best performance is achieved with norm-based user selection, Gram-Schmidt antenna selection and MMSE receivers.