Sceye and SoftBank tested live mobile service from a high-altitude platform in Japan, using the airship to provide backup connectivity after local cellular coverage was switched off, according to Ars Technica’s reporting on an interview with Sceye CTO Johnny Truong. SoftBank says the trial connected the platform to its core network through a ground gateway. The partners are preparing for possible commercialization in Japan from 2027 onward, according to SoftBank’s announcement.

How the HAPS connected to SoftBank’s network

A high-altitude platform station, or HAPS, is an uncrewed, lighter-than-air platform designed to operate high above the ground. During the trial, SoftBank says, a 4G LTE-equivalent base station aboard Sceye’s platform connected to SoftBank’s core network through a gateway on the ground.

SoftBank places the test area around Muroto City in Kochi Prefecture, off Cape Muroto. It says the platform held position within a radius as small as 5 km during the operation. That describes the reported station-keeping area, not the extent of cellular coverage.

What the trial tested

SoftBank reports tests of voice calls, texts, apps, video streaming and video calls, emergency alerts, and calls to Japan’s 118 maritime emergency number. It also reports successful tests of drone remote control, location data and video transmission over the HAPS connection.

SoftBank says communications performed comparably to terrestrial networks while reducing radio interference with ground base stations. Those results came from the companies’ trial. They also tested the system in a live-service scenario: Ars Technica reporter Jeremy Hsu reported that SoftBank disabled local cellular coverage before Sceye’s platform supplied backup service.

What the onboard computing test measured

In a separate edge-computing test, a server aboard the HAPS processed data closer to the connected devices than a remote internet-based cloud server would. SoftBank reports an average 68-millisecond round-trip processing response and a latency reduction of more than 40% compared with cloud processing over the internet.

Sceye says a full-scale HAPS is designed to cover an area equivalent to about 500 terrestrial towers. That is a design claim for a full-scale platform, not a coverage result measured during the ST1 trial.

ST1 completed its trans-Pacific mission in September

Sceye’s Service Test 1 (ST1) platform departed New Mexico on August 9, 2026, and reached Japanese airspace on August 23 after a crossing of more than 15,000 km, SoftBank says. Sceye reported that the platform re-entered U.S. airspace on September 4 and reached airspace near Moriarty, New Mexico, on September 5, where it completed additional vehicle testing before its planned termination and descent. In a September 9 announcement, Sceye described the mission as a 30-day, nearly 30,000-km round trip.

SoftBank says it is preparing for possible commercialization in Japan from 2027 onward.