SoftBank detailed plans to fly high-altitude platform station (HAPS) aircraft designed to deliver direct-to-device network coverage over Japan.

The launch is planned for this summer and will see the Japanese carrier partner with U.S.-based Sceye, which it made a major investment in last year.

Sceye specializes in developing lighter-than-air (LTA)-type HAPS vehicles, similar to zeppelins or blimps. The SoftBank trial will see one such aircraft launch from Sceye’s Roswell, New Mexico, hangar and travel across the Pacific to Japan under satellite-based control. After reaching Japanese airspace, the craft will establish a link with a ground gateway in Kochi Prefecture on Shikoku Island, located on Japan’s Pacific coast.

The demo aims to deploy smartphone connectivity to simulate possible connectivity solutions in the event of a major disaster, such as the earthquake that beset Japan’s Kumamoto prefecture last week.

Sceye recently completed a 12-day, 6,400-mile stratospheric flight using its SE2 HAPS model, traversing from New Mexico to the coast of Brazil.

SoftBank intends its claimed record test flight will test whether the aircraft can reproduce the same flight performance under Japan’s unique weather and environmental conditions. It also aims to test if telecom services can be delivered from an altitude of approximately 12.4 miles at a quality comparable with terrestrial mobile service and whether HAPS radio transmissions cause harmful interference to surrounding ground-based mobile networks.

SoftBank said the preceding aircraft, network, and gateway preparations have now been completed. It also completed an end-to-end communications test linking the equipment intended for the HAPS aircraft to its Japanese mobile core. The operator successfully tested voice calls, text messaging, and mobile data across the complete Japan–United States path, verifying that a normal handset could communicate through the planned HAPS access equipment and onward into the operator’s existing core-network environment.

HAPS forms part of SoftBank’s wider Ubiquitous Transformation (UTX) strategy, which aims to complement terrestrial mobile networks with non-terrestrial infrastructure in the event of disasters. Rival telecom operator NTT DoCoMo has similar ventures, claiming recently to have carried over five million connections to its consumer-facing Starlink service.

SoftBank also has a Starlink-based service, but stressed that its Starlink Direct is intended to provide basic communications principally for mountains, islands, marine areas, and other locations outside ordinary network coverage. The HAPS service is intended for suburban areas, aerial applications, and other uncovered locations that require service closer to the quality and capacity of a terrestrial network, with a maximum diameter of about 200 kilometers in coverage per aircraft. This offers a more localized, higher-capacity layer capable of supporting ordinary voice, messaging, and data services.

SoftBank added that commercial HAPS operations are targeted to begin next year at the earliest.

“Our vision is to expand today's 2D communications infrastructure into a 3D communication network extending into space," Masayuki Kamimura, senior director at SoftBank’s Ubiquitous Network Planning Division, noted in a statement. "To achieve this, we’ll connect multiple HAPS platforms with low-Earth orbit (LEO) satellites using optical wireless communications, creating a multilayered, 3D telecommunications network. Ultimately, we believe this network will support future innovations such as advanced mobility and AI-enabled services, while contributing to a broader digital transformation across society."