Outdoor experiment on user mobility using distributed MIMO beamforming for 5G radio access

This paper presents outdoor experimental results with a 4 layer single-user (SU)-multiple-input multiple-output (MIMO) 5G cellular radio access system. Beam tracking with narrow beams are evaluated in the 15-GHz frequency band in order to investigate the effects of user mobility. In addition, distributed MIMO beamforming functionality is implemented to extend coverage using multiple transmission points (TPs) supporting 2 layers each. The experimental result in an outdoor open space environment shows that the peak throughput is 12.1 Gbps on a public road at an average speed of approximately 10 km/h. The result also shows that more than 8 Gbps is achieved at an average speed of approximately 40 km/h. Furthermore, it is observed that throughput is remarkably degraded when the difference in the received power between the best and second best transmission point is larger than 15 dB and only 2 layer spatial multiplexing is supported from one of the transmission points.