High Speed Mobility Experiments on Distributed MIMO Beamforming for 5G Radio Access in 28-GHz Band

This paper describes the results of outdoor mobility measurements and high-speed vehicle tests that clarify the 4-by-8 multiple-input multiple-output (MIMO) throughput performance when applying distributed MIMO with narrow antenna-beam tracking in a 28-GHz frequency band in the downlink of a 5G cellular radio access system. To clarify suitable transmission point (TP) deployment for mobile stations (MS) moving at high speed, we examine two arrangements for 3 TPs. The first sets all TPs in a line along the same side of the path traversed by the MS, and the other sets one TP on the other side of the path. The experiments in which the MS is installed on a moving wagon reveal that the latter deployment case enables a high peak data rate and high average throughput performance exhibiting the peak throughput of 15 Gbps at the vehicle speed of 3 km/h. Setting the MS in a vehicle travelling at 30 km/h yielded the peak throughput of 13 Gbps. The peak throughput of 11 Gbps is achieved at the vehicle speed of 100 km/h, and beam tracking and intra-baseband unit hand over operation are successfully demonstrated even at this high vehicle speed.