Spectral Efficiency of mmWave Massive MIMO Systems with Hybrid Beamforming

Millimeter wave communications (mmWave) has been considered a key enabling technique for 5G systems since it offers orders of magnitude more spectrum than current frequency bands. Unlike conventional multiple input multiple output (MIMO) networks, beamforming in millimeter-wave systems cannot be accomplished using digital techniques since only a limited number of analog-to-digital converters and mixers can be handled due to their cost and power consumption. Recently, there has been a lot of interest in a hybrid beamforming transceiver design, which includes an analog and digital beamformer, as a less expensive alternative. However, the optimal design for these hybrid beamformers has not yet been fully established. In order to approach the complex performance of the fully digital beamformer, this work will provide efficient alternative minimization techniques for a hybrid beamforming structure, namely the manifold-based geometric fully-connected antennas. According to simulation data on bandwidth efficiency, the proposed iterative algorithm performs much better than the baseline hybrid beamforming approach, namely the MMSE-MP algorithm (about 6.8% for a particular situation). Additionally, based on the recommended techniques, comparing the simulation results of the two hybrid beamforming structures will yield vital design information.