Hybrid Alternating Precoding and Combining Design for mmWave Multi-User MIMO Systems

This paper investigates the hybrid beamforming for multi-user millimeter wave (mmWave) multiple-input-multiple-output (MIMO) systems under the sub-connected architecture where each antenna is only connected to a unique radio frequency (RF) chain. Based on the perfect knowledge of the channel state information (CSI), the analog combiner for each user is achieved by using the singular value decomposition (SVD), and the analog and digital precoder is achieved by minimizing the Frobenius norm of the matrix of difference between the unconstrained precoder matrix and products of the hybrid RF and baseband precoders via the alternating optimization approach. Simulation results show that the performance of our proposed method over the existing SVD-based approaches in terms of achievable sum rate with different scales of transmit and receive antenna array, especially in the low signal to noise ratio (SNR) regime.