Japan’s NTT Docomo and Huawei Technologies have recently completed a trial using integrated access backhaul (IAB) technology to significantly boost millimeter wave (mmWave) coverage and capacity.
The field trial, conducted in Yokohama, Japan's Minato Mirai 21 waterfront area, involved wireless backhauling functionality between a 5G base station and a 5G relay node using 39-GHz signals.
According to Docomo, the trial confirmed that IAB technology can significantly improve mmWave coverage and capacity. Throughput exceeding 650Mbps with latency of 1.6 ms was achieved with user equipment that was outside the range of the base station.
It also proved that IAB facilitates the use of high-speed, low-latency 5G communication among tall buildings and on isolated islands or in mountain regions where laying fiber presents problems, Docomo said.
Conventionally, mmWave signals offer only limited coverage due to high propagation loss and interference from buildings. The need for a narrow directional beam to focus transmission power can further complicate efforts to achieve wide area coverage under non-line-of-sight conditions.
According to Docomo, the 3GPP standards organization is considering IAB technology as a 5G New Radio (NR) standard. The technology involves the use of a compact focal lens antenna made with metamaterials to achieve advanced beamforming (maximum gain of 31 dBi) that concentrates radio waves in a specified direction for long-distance transmission.
Beamforming mitigates interference between the wireless backhaul and wireless access links. It also enables simultaneous data transmissions over the same frequency. In addition, IAB nodes enable low-latency data transmissions through fast beam-switching for the uplink and downlink, and they efficiently coordinate radio resource scheduling between the backhaul and access links.
The IAB trial system involved a 5G base station (IAB-donor) and a 5G relay station (IAB-node).
Source: NTT Docomo