Switching between beamforming and space-time block coding for correlation-varying channel

As the spatial correlation increases, the performance of space-time block coding (STBC) degrades to the extent that the communication breaks off. On the other hand, receive beamforming can exploit the spatial correlation. In order to avoid the blackout caused by the high correlation, we propose a scheme that switches between beamforming and STBC (SBS) with explicit switching criteria to dynamically accommodate the changing channel correlation. In the further discussion, we find that the switching criterion results in the undesirably frequent switching when the Doppler frequency increases. As a result, we propose a statistical criterion to achieve a much lower switching frequency while keeping almost the same performance as the previously proposed scheme. Simulation results are provided to confirm the validity of our proposed schemes.