Japanese operator NTT Docomo has announced that, in a joint trial of 5G technologies with Samsung Electronics, it has successfully achieved a data speed of more than 2.5Gbps with a mobile device that was in a vehicle travelling 150km per hour, thereby verifying the feasibility of stable connectivity for 5G mobile devices in fast-moving trains.
The trial took place on 7 November in Fuji Speedway, a motorsport racing circuit in Shizuoka Prefecture, Japan. Transmissions were conducted using the 28GHz high-frequency band, one of the candidate bands that the Ministry of Internal Affairs and Communications is considering to designate for commercial 5G networks in Japan.
The trial used MIMO technologies that incorporate beamforming, which concentrates radio waves in a specific direction, and beam tracking, which adjusts the beam according to the fast-moving mobile device's location.
In a separate undertaking, Docomo conducted an outdoor data-transmission trial with Huawei from 3 to 26 October. The trial was carried out in a field measuring 100,000 square meters, in the Minato Mirai 21 waterfront of Yokohama. The trial involved 23 simultaneously connected mobile devices and achieved a cumulative 11.29Gbps of data throughput and latency below 0.5 seconds using the 4.5GHz frequency band, Docomo said.
The trial combined multi-user MIMO (MU-MIMO) technology for simultaneous multiple access and a precoding algorithm designed to optimize signals for maximized performance and also limit inter-user interference. Docomo said it achieved a MU-MIMO transmission of a maximum 79.82bps/Hz/cell, which was 1.8 times more efficient than an outdoor trial conducted in China in November 2015.
