Vector quantized phase shift analog beamformers for millimeter-wave systems

Millimeter-wave (MMW) is a probable technology for the future cellular systems. Its main challenge is achieving sufficient operating link margin, and directional beamforming with large antenna arrays may be a viable approach. With bandwidths on the order of gigahertz, high-resolution analog-to-digital converters are a power consumption bottleneck. One solution is to employ an hybrid implementation, digital at baseband and analog at radio frequencies. In this paper we develop two iterative hybrid beamforming design algorithms for the MMW channel, using vector quantization of the analog beamformers. The proposed algorithms accounts for the RF precoding constraints and assumes the channel matrix is known but not the ray phase vector responses. We compare the proposed algorithms with the state-of-art hybrid schemes and the simulation results show that performance of the proposed algorithms can approximate that of the maximum-ratio-beamforming upper bound even if computational complexity may be higher for systems with small number of antennas.