• SoftBank and Sceye tested mobile services from a HAPS that travelled more than 15,000km from New Mexico to Japan and operated in Japanese airspace for more than seven days
  • The platform connected ordinary smartphones through SoftBank's network and also carried an onboard mobile core for an edge-computing test

The fact

SoftBank and US aerospace company Sceye have completed a HAPS communications trial in Japan as the Japanese operator works towards commercial service from 2027 onward. Sceye's lighter-than-air high-altitude platform travelled more than 15,000km from New Mexico to Japan in 13 days before operating in Japanese managed airspace for more than seven days.

During the trial near Cape Muroto in Kochi Prefecture, a mobile base station aboard the platform connected ordinary smartphones to SoftBank's core network through a ground gateway. SoftBank tested voice calls, text messages, emergency calls, video streaming and video calls, while the platform also communicated with drones. Sceye said the aircraft operated at about 16.5km altitude and at one point maintained its position within a radius of about 5km despite changing stratospheric conditions.

SoftBank also installed a mobile core and web server aboard the platform for an edge-computing test. The company said smartphone traffic could then be processed on the HAPS without travelling through the terrestrial network. SoftBank described this as a world first based on its review of publicly available information.

The assessment

The trial matters because it brought several parts of a HAPS service together in one mission. The aircraft travelled from the US to Japan, held position over a defined area, connected ordinary smartphones and carried traffic into SoftBank's mobile network. That is a more demanding test than simply showing that a phone can connect to a base station in the stratosphere.

What SoftBank has not shown is whether the service can run continuously. A commercial HAPS network would need the aircraft to stay in position for long periods while the radio link, ground gateways and core-network functions remain stable. SoftBank has not disclosed the capacity available to users, expected service availability or the cost of keeping that coverage in place.

For BTW readers, the gap is now between a successful flight and a dependable network service. SoftBank has shown that the pieces can work together. Repeat missions, longer station-keeping and published capacity and availability figures will show whether they can do so reliably enough for commercial use.

What to watch

Watch whether SoftBank begins commercial HAPS services from 2027 onward and what the first deployment is used for. Operating duration, coverage area, available capacity and the number of platforms required to maintain service will be important. Details on ground gateways and network integration would also show how much terrestrial infrastructure is still required.