Indoor and Outdoor Experiments on 5G Radio Access Using Distributed MIMO and Beamforming in 15 GHz Frequency Band

This paper presents indoor and outdoor field experimental results that clarify the 4-by-8 MIMO throughput performance when applying distributed multiple-input multiple-output (MIMO) with a narrow antenna beam tracking in the 15 GHz frequency band in the downlink of a 5G cellular radio access system. The experimental results show that throughput exceeding 15 Gbps is achieved with a high average rank of 4 at an indoor office building lobby and outdoor parking area. As for the distributed MIMO gain in terms of throughput in LoS environments, we achieve throughput gain of 39 % and 105 % in the indoor office building lobby and outdoor parking area, respectively. And also throughput gain of 15 % is achieved in N-LoS environment in office building lobby in multi-path rich environment. We also observe a significant increase of throughput and rank when changing the transmission point (TP) spacing from 0.5 to 1.5 m, while only a limited performance improvement when the TP spacing exceeds 1.5 m. Finally, the throughput performance with various TP positions was tested, and the TP locations when facing each other with a TP spacing of 50 m exhibit excellent performance exceeding 10 Gpbs.