Hybrid Beamforming Design for Multiuser Massive MIMO-OFDM Systems

A multiuser hybrid beamforming system with orthogonal frequency division multiplexing (OFDM) is considered. We propose an alternating optimization algorithm based on manifold optimization to maximize the performance in terms of the system spectral efficiency. Moreover, two simplified methods with low complexity are also proposed which are of practical relevance for massive MIMO. The proposed methods are verified by simulation results to have smaller spectral efficiency gaps with the fully-digital beamforming than the scheme in another recent research. With the proposed designs, significant cost savings are obtained with only marginal loss in performance.