Japan’s largest operator NTT Docomo carried out a variety of supposed 5G trials with five equipment vendors over the past two months.
Docomo and Ericsson last week verified the feasibility of massive multiple-input multiple-output (MIMO) technology by achieving a real-time data-receiving speed of more than 10Gb/s using the vendor’s 5G radio prototypes with a 15GHz frequency band.
Meanwhile an outdoor data transmission trial conducted a week ago by Docomo, Docomo Beijing Communications Laboratories and Huawei reached a multi-user MIMO (MU-MIMO) transmission of 43.9bps/Hz/cell, which was 3.6-times more efficient than past outdoor trials of LTE-Advanced based MU-MIMO technology.
In a separate trial conducted with Samsung in Suwon-city, South Korea, on 12 November, the two firms attained a maximum data-receiving speed of more than 2.5Gb/s in a vehicle travelling at a speed of 60km/h. The trial used a 28GHz high-frequency signal in combination with beamforming, which focuses radio waves in a specific direction, with a high number of antenna elements and beam tracking.
At the end of October the operator and Fujitsu confirmed a multi-base-station cooperative transmission system by achieving a data-receiving speed of more than 11Gb/s via a total of four mobile devices with a 4.6GHz signal.
Also in October, Docomo and Nokia Networks reached a data rate of more than 2Gb/s using high-frequency spectrum in a trial in the Roppongi Hills high-rise complex in Tokyo using millimeter-wavelength signals in the 70GHz band. The trial used beamforming and beam tracking to control beam direction according to the mobile device’s location.
Despite Docomo’s 5G claim, it remains uncertain as to what will eventually comprise a set of 5G standards. The technology is not due to be ratified for at least another year.
The operator has said it wants to launch the technology in time for the 2020 Olympics in Tokyo.