Overlapped Sub-Array based Hybrid Beamforming for Millimeter Wave Multi-User Massive MIMO

For massive Multiple Input Multiple Output (MIMO) systems at Millimeter Wave (mmWave) bands, we consider an efficient hybrid array architecture, namely Overlapped Sub-Array (OSA), and develop a Unified Low Rank Sparse recovery algorithm (ULoRaS) for hybrid beamforming in downlink multi-user scenarios. The ULoRaS scheme takes advantage of the transmit-receive coordinated beamforming procedure to achieve large array gains. It has no dimensionality constraint and can be applied to the generalized OSA architecture, including both the fully-connected and the widely discussed non-overlapped subarray cases. It is shown that the proposed ULoRaS algorithm for the novel OSA design is a good compromise of the performance and the required hardware complexity.