Reducing codebook loss with reconfigurable receive antennas

Abstract

In this paper, a reconfigurable antenna codebook feedback scheme is investigated to reduce precoding codebook loss without increasing the number of feedback bits. Analysis and simulations show that increasing the number of receive antenna states (S) has the same effect as codebook size expansion when the codeword and state selection is based on minimizing the distance between channel and codeword.In addition, we propose an optimum selection approach. The SNR and rates achieved with perfect feedback in a traditional non-reconfigurable antenna system, can be exceeded with only S = 2, using the proposed optimum selection. In fact doubling S gives an approximate SNR gain of 40 % compared to S = 1. We also consider the effects of channel estimation errors and correlated antenna states. We show that the performance losses due to correlation can be quantified with a simple closed form result. Index TermsReconfigurable antenna, limited feedback, precoding, codebook, MISO, beamforming. P. J. Smith was with the University of Canterbury † during this research.