Quantization with Combined Codebook for Hybrid Array using Two-Phase-Shifter Structure

TL;DR: A new codebook design is proposed that combines the two codebooks of the two phase shifters in the recently proposed 2-PS structure, and a low-complexity searching algorithm for finding a near-optimal scalar based on element-wise quantization is proposed.

Abstract: We propose a novel joint quantization scheme for hybrid antenna array systems using the two-phase-shifter (2-PS) structure, where two phase shifters are combined to represent one beamforming weight. Conventional quantization using a single phase shifter for each beamforming weight cannot represent the magnitude. We propose a new codebook design that combines the two codebooks of the two phase shifters in the recently proposed 2-PS structure. We also study the scaling problem of the beamforming vector and propose a low-complexity searching algorithm for finding a near-optimal scalar based on element-wise quantization. The mean squared quantization error and signal-to-noise ratio (SNR) degradation are derived analytically. Simulation results validate the accuracy of the analytical results and the effectiveness of the proposed quantization methods.