Adaptive codebook for beamforming in limited feedback MIMO systems

We propose a new scheme for limited feedback in MIMO systems. We consider transmit beamforming and receiver maximal ratio combining as a base for our work, and propose a novel beamforming codebook to exploit the inherent correlation of the channel. This novel beamforming codebook, unlike the conventional beamforming codebooks, adaptively changes with the channel matrix. Moreover, the adaptive approach is independent of the channel model and can be applied to any general MIMO channel with temporal and spatial correlations. Simulation results show that compared to previously known beamforming schemes, this technique significantly improves the BER performance in spatio-temporally correlated channels.