MIMO relay wireless networks with scheduling and transmit beamforming

In this paper, we investigate the performance of a multiuser wireless relay network with each of its nodes equipped with N antennas and transmit beamforming at its source and relay, where multiuser diversity (MD) is exploited to further improve the system performance. In the first part of this paper, by deriving the approximate error performance expression for a single-relay MD system without the direct link, we obtain the maximum diversity order achievable by the CSI-assisted amplify-and-forward (CAF) protocol. Then, by taking the direct link into consideration, we propose a sub-optimal transmit beamforming scheme and show the performance loss is very small. Copyright (c) 2010 John Wiley & Sons, Ltd.