SoftBank Successfully Tests Japan’s First ‘Flying Base Station’

SoftBank has successfully tested Japan’s first “flying base station,” transmitting radio signals to the ground from an unmanned aircraft flying in the stratosphere.

The company conducted the test over Muroto in Kochi Prefecture on Aug. 23 and 24. The balloon-shaped drone used high-altitude platform station, or HAPS, technology to determine whether it could support voice calls, emergency calls, video calls and communications with other drones.

A HAPS station can remain in the stratosphere, about 20 kilometers above the ground, for several months to half a year. SoftBank designed each station to cover an area with a diameter of up to 200 kilometers. Because the signal travels from 20 kilometers above Earth rather than from low-Earth orbit more than 300 kilometers away, the company says the system could offer high-quality, high-capacity communications similar to ground-based stations.

SoftBank plans to expand the platform’s coverage and flight duration in 2027, then begin offering it as a business communications service under normal conditions. The technology is also intended for earthquakes, storms and floods, as well as mountainous areas and remote islands where ground infrastructure is difficult to build.

The prospect has drawn competition from other Japanese telecommunications companies. NTT Docomo plans similar tests in Ishikawa Prefecture’s Noto region in September. Commercial deployment still faces challenges, including long-duration flight, changing weather conditions and maintaining a stable radio supply. If ground stations are damaged by earthquakes or tsunamis, HAPS could provide another way to restore communications in affected areas.