Reducing codebook loss by using reconfigurable receive antennas in limited feedback precoded MIMO systems

Abstract

It is known that the performance of limited feedback precoding systems depends on the size of the codebook, determined by the number of feedback bits. Increasing the number of feedback bits improves performance. However, this in turn requires a significant increase in the control channel bandwidth. The goal of the proposed reconfigurable antenna codebook scheme is to improve the closed-loop precoding gain without increasing the number of feedback bits. We employ reconfigurable antennas at the receiver resulting in multiple possible channel conditions. We have shown through simulations that increasing the number of receive antenna states has the same effect as a bigger codebook in terms of received signal to noise ratio gain, improved symbol error rate and sum rate gain. Different codeword and RA state selection methods are considered for both single and multi-layer transmissions and different system sizes, using LTE and Grassmannian codebooks with MMSE and SVD receivers.