Hybrid Beamforming Design for Uplink mmWave Systems with a Predefined Low-Resolution Codebook

In millimeter wave (mmWave) systems, desirable spectral efficiency can be realized by the hybrid beamformer in which a large sized analog beamformer and a small sized baseband digital beamformer are cascade-connected together to reduce the system cost. However, most of works focus on the beamforming (or combining) method design with an impractical analog beamformer where the infinite-resolution phase shifts (PSs) are adopted. In this paper, a more practical hybrid beamformer with low-resolution PSs is considered and the hybrid receiver beamforming method under the multiuser uplink communication circumstance is studied. Since the system performance is mainly constrained by the interuser interference, we propose a novel two-stage hybrid receiver beamforming against the inter-user interference with comparable computational complexity than that of the recently presented method. Moreover, to enhance the performance of systems with many users, we propose a novel multiuser selection algorithm by exploiting the multiuser diversity gain. Finally, from the simulation results, we can verify the superiority of the proposed method over the comparing method in error probability and spectrum efficiency.