Indoor Experimental Trial In High Shf Wide-Band Massive Mimo Hybrid Beamforming

The fifth-generation (5G) mobile communication system introduces the use of high frequency bands with very wide bandwidth for realizing super high bit rate more than 20 Gbps. To use such high frequency bands, Massive MIMO technologies by hybrid beamforming is a promising technology in terms of power consumption and implementation cost. Experimental trials of hybrid beamforming in 28 GHz band were already conducted in an indoor anechoic chamber and in an outdoor light-of-sight (LOS) environment. However, as MIMO takes advantage of multipath, it is important to evaluate the system performance in multipath-rich environment. It is also important to evaluate the system performance in non LOS (NLOS) environment, because high straightness of high SHF band can degrade its performance. To clarify these actual impacts, in multipath-rich room with some obstacles, we conducted two indoor downlink experimental trials: SU-MIMO and 8-user MU-MIMO at 28 GHz frequency band with 500 MHz bandwidth. The results of SU-MIMO experiments show more than 20 Gbps user throughput was achieved in the multipath- rich environment. We also confirmed that strong reflector improves the throughput when a user is in the NLOS environment. MU-MIMO experiments show the hybrid beamforming can improve both the system throughput and user fairness compared to analog beamforming.