Japanese mobile operator NTT DOCOMO and equipment manufacturer Mitsubishi Electric claim to have achieved peak data speeds of up to 27Gbps over short distances in a proof-of-concept (PoC) 5G trial using a single mobile terminal and 500MHz of spectrum in the 28GHz band. In a press release, the pair say in outdoor field trials they reached downlink data rates of 27Gbps and 25Gbps, respectively, over distances of 10m and 100m. The two firms claimed the results are ‘the world’s first 5G transmission to a mobile terminal exceeding a peak data rate of 20Gbps’. The trial, which took place in Kamakura, Kanagawa Prefecture, Japan from 10-28 September 2018, was used to verify the feasibility of 16-beam spatial multiplexing in line-of-sight (LOS) conditions, where massive-element base-station antennas on the wall of a building directed beams to mobile-terminal antennas installed on the rooftop of a vehicle. The companies are planning multipath-rich environment indoor trials using the 28GHz band in the fiscal year ending 31 March 2019.
By way of background, DOCOMO and Mitsubishi noted in the release: ‘A peak data rate of 20Gbps is required for 5G mobile communications. One technology that promise to meet this need is massive-element antenna systems technology, which enables multi-beam spatial multiplexing where multiple data streams can be transmitted in parallel to mobile terminals. Realising this technology, however, has involved two challenges: implementation of a massive-element antenna array that clusters large numbers of antenna elements for high-precision beamforming, and mitigation of inter-beam interference.’