Mitsubishi Electric and NTT DOCOMO have have shown the world's first 5G proof of concept for 27Gbps and 25Gbps maximum throughputs via one mobile terminal over communication distances of 10m and 100m, respectively, using the 28GHz radio frequency.
The demonstration in Japan was conducted during joint outdoor field trials using 28GHz-band massive element antenna systems and 16-beam spatial-multiplexing technology with 500MHz bandwidth.
For outdoor trials using the 28GHz band, Mitsubishi Electric used an antenna system with 16-beam spatial-multiplexing technology . Base-station antennas installed on the wall of a building directed beams to mobile-terminal antennas installed on the rooftop of a vehicle and showed successful wireless downlink transmission at maximum data rates of 27Gbps and 25Gbps for per one mobile terminal when the communication distance was 10m and 100m, respectively.
The 16-beam spatial-multiplexing technology consists of eight analogue, front-end processing, low-power units to form 16 beams and a multiple-input multiple-output (MIMO) digital processing algorithm to reduce inter-beam interference.
Conventional 4G spatial multiplexing technology has limited multiplexing order, so Mitsubishi Electric and DOCOMO developed beamforming technology in an analogue domain and inter-beam interference reduction technology to suitably separate overlapping beams with digital signal processing at the base station. The result is 16-beam spatial multiplexing, which has been unachievable with 4G.
The developed beamforming technology enables beams to track a mobile terminal by switching the preset beam and the inter-beam interference reduction technology estimates the channel at the base station and controls the transmitting signal to adaptively reduce inter-beam interference as channel conditions over time. Together, the two technologies enable 16-beam spatial multiplexing in outdoor mobile environments.
The achieved peak data rates correspond to spectral efficiency of 67bps/Hz4 , believed to be the world’s best performance for 28GHz-band mobile telecommunication. This is expected to enable wireless communications at ultra-high data rates of more than 20Gbps to moving vehicles with numerous passengers, such as buses.