Performance of Hybrid Codebook Techniques for MISO Downlink Channels with Limited Feedback

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 ((PURC)-R-2) which has been proposed for emerging cellular standards. In order to have good performance, ZFBF requires many feedback bits, and (PURC)-R-2 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.