Angle-Based Codebook for Low-Resolution Hybrid Precoding in Millimeter-Wave Massive MIMO Systems

Hybrid precoding is a promising technique for millimeter-wave massive MIMO systems, as it can significantly reduce the number of radio-frequency (RF) chains with nearoptimal performance. To further reduce the power consumption, low-resolution hybrid precoding utilizing low-resolution phase shifters is recently proposed without an obvious performance loss. However, traditional channel feedback codebooks that quantize the channel with high resolution are not suitable to low-resolution hybrid precoding. In this paper, we design an angle-based codebook for low-resolution hybrid precoding, where the analog codebook is designed based on channel angle-of-departures (AoDs), while the digital codebook is designed by random vector quantization (RVQ). As the angle coherence time is much longer than the channel coherence time, the selected analog codeword from the analog codebook remains unchanged in a much longer time scale. Thus, the channel feedback overhead can be significantly reduced. Simulation results illustrate that the proposed codebook with low overhead for channel feedback is able to achieve the acceptable sum-rate performance.