Outdoor Experimental Trials on Deployments of Multiple Base Station Antennas for 28 GHz-Band Cooperated Digital Beamforming

5G introduces a beamforming (BF) technology using massive MIMO. In further enhancement of 5G (5G evolution: 5GE), which will be actualized around 2025, performance improvement by digital precoding for hybrid BF and fully digital BF technologies can be expected. In addition, a cooperation technology of multiple base stations (BSs) is required to provide high data rate communications in millimeter wave bands, even when mobile stations (MSs) move at high speed. This paper describes 28 GHz-band experimental equipment that implemented a novel BS cooperation technology combined with digital BF. In outdoor experimental trials, measured downlink throughput is clarified, when three BS antennas are deployed in two kinds of directions and one MS moves at 90 km/h.