Performance of hybrid codebook techniques for MISO downlink channels with limited feedback

Abstract

Multi-antenna downlink system with limited feedback can provide enormous capacity gains. In practical, two systems can be considered. One is zero-forcing beamforming (ZFBF), and the other is per user unitary rate control (PU2RC) which has been proposed for emerging cellular standards. In order to have good performance, ZFBF requires many feedback bits, and PU2RC requires many users. Recently, the authors proposed a hybrid multi-user MISO system which has merits of those two schemes simultaneously. In this paper, we analyze the sum-rate performance and quantization error of the hybrid scheme. The throughput scaling laws are also derived in high and medium SNR regimes.