TOKYO, Japan – While thousands of Starlink satellites currently orbit Earth, some companies are looking to connect us from a slightly different altitude.
Tokyo’s SoftBank Corp. is poised to launch a stratospheric 4G and 5G service in 2026, potentially challenging satellite internet providers.
- SoftBank Corp. will deploy a stratospheric airship for 4G and 5G service over Japan starting in 2026.
- The airship, developed by Sceye, will operate 20 kilometers above Earth, offering lower latency than some satellite services.
- The project leverages newly allocated lower-frequency spectrum, enabling direct-to-device connections.
- The airship can stay aloft for months and potentially replace up to 25 ground towers.
SoftBank Corp. announced last month it secured exclusive rights to deploy lighter-than-air craft in Japan’s stratosphere. Starting next year, a prototype airship will beam 4G and 5G phone and broadband service to users on the ground. This move could present a competitive threat to satellite-based platforms like Starlink.
A Stratospheric Technical Blueprint
The airship, developed by Moriarty, N.M.-based Sceye, will function as an autonomously piloted cell tower. It will carry the same base station technology found in terrestrial towers, adhering to global broadband standards set by the Third Generation Partnership Project (3GPP).
“The mobile phone doesn’t know the difference between our platform and a tower,” says Mikkel Vestergaard Frandsen, Sceye’s CEO. “We just plug into existing infrastructure and operate under the same 3GPP protocol.”
This system uses advanced beamforming technology to direct signals precisely, either covering wide areas or concentrating bandwidth where demand is high. Sceye reports a latency of under 20 milliseconds, potentially outperforming Starlink’s reported 45 ms.
Frandsen emphasizes, “This is not a relay system, we are the base station, able to respond to network demand from the stratosphere.”
The solar-powered airship, which has completed over 20 successful test flights, boasts a 250-kilogram payload capacity and 10 kilowatts of solar power. This allows it to maintain its position, unlike balloons or fixed-wing drones that are subject to drift or have limited power.
Sceye’s material innovations are key to the airship’s endurance. Its hull fabric is five times stronger per unit mass than conventional materials used for high-altitude platform systems (HAPS). It is also 1,500 times more gas-tight and resistant to UV and ozone damage.
“There’s a lot of overlap between extreme sports like the America’s Cup or Formula One and our work on HAPS,” Frandsen said. “It’s all about pushing materials to the limit, safely.”
Vincenzo Rosario Baraniello, Head of Earth Observation Systems at the Italian Aerospace Research Centre, notes that structural and energy system efficiencies are critical. “Improving those technologies gives a competitive advantage,” he stated.
The airships are designed for long-duration flights, capable of remaining in their operational area for months. Ultra-lightweight solar skins and high-density battery packs power the equipment overnight. The temperature- and UV-shielded compartment can handle extreme stratospheric conditions. A single airship can potentially replace up to 25 ground towers.
Leveraging New Spectrum
Nikolai Vassiliev, chief of Terrestrial Services at the International Telecommunication Union, believes the time is right for stratospheric systems. “We have established power limits, coordination rules, and harmonized bands,” he said. “Now it’s up to operators to deploy.”
Previously, HAPS relied on millimeter-wave spectrum, which has limited range and is vulnerable to weather. However, the 2023 World Radiocommunication Conference opened up microwave bands between 700 megahertz and 2.6 GHz for HAPS.
These lower-frequency bands enable direct-to-device connections from stratospheric platforms. “The availability of harmonized, low-band spectrum for direct-to-device HAPS has fundamentally changed the business case,” said Toshiharu Sumiyoshi of SoftBank’s Ubiquitous Network Planning Division. “We can now deliver service with commercially available handsets.”
Unlike earlier platforms that acted as signal relays, Sceye’s high-altitude towers will offer seamless service through handovers between ground and aerial nodes. This should feel similar to existing terrestrial 4G and 5G coverage for end-users.
SoftBank is considering deploying the platforms for continuous service or as on-demand responders during emergencies. “Our current plan aims for one aircraft to stay in the air for one year,” Sumiyoshi stated. Operational details will be finalized after pre-commercial testing in 2026.
Baraniello highlighted the significance of the partnership, saying, “The partnership between Sceye and SoftBank is significant. It shows that these platforms have reached a level of technological maturity that allows them to be deployed operationally.” He added, “From an aerospace engineering standpoint, that’s a big deal, and the market’s interest will further push research, industry, and development forward.”
