Adaptive beamforming with antenna selection in MIMO systems

Selection diversity at both the transmitter and receiver is the simplest way to realize MIMO (multiple-input multiple-output) systems, but the performance improvement of this form of diversity technique is limited. Adaptive beamforming based MIMO can provide significant increases in a system's capacity and performance, but it is characterized by a relatively higher implementation complexity than selection diversity. We propose an adaptive beamforming with antenna selection for MIMO wireless transmission systems. By adaptively selecting the best beamforming which corresponds to the largest eigenvalue in the subset of all available channel correlation matrices, the proposed system can get significant performance improvements over the conventional adaptive antenna array based MIMO systems and the selective space-time block coding approach over flat fading channels. Numerical results also show that the proposed approach always outperforms the selective space-time coding approach under imperfect CSI.