Sceye and SoftBank Test High-Altitude Platform Station as Floating Cell Tower in the Stratosphere
The Stratosphere as the Next Telecom Frontier
A New Mexico-based company called Sceye, backed by Japanese telecom giant SoftBank, is preparing to test an autonomous solar-powered airship as a floating cell tower 20 kilometers above the Earth. The technology, known as a High-Altitude Platform Station (HAPS), could become a critical component of future mobile networks by bridging the gap between ground towers and satellites.
The Pacific Crossing
Later this year, Sceye's helium-filled airship will lift off from New Mexico for its longest flight yet — a Pacific crossing to Japan, where the real testing begins. In partnership with SoftBank, the company will evaluate the craft's ability to serve as a persistent base station in the stratosphere.
How HAPS Works
Sceye's airship is an autonomously piloted, helium-filled vehicle that:
- Operates on solar power during the day and battery power at night
- Maintains position at 20 km altitude using electric fans
- Can carry payloads up to 250 kg — far exceeding fixed-wing competitors
- Stays above ground weather but must fight fierce stratospheric winds
SceyeCELL: The Stratospheric Antenna
The key technology being tested in Japan is SceyeCELL, a MIMO antenna module designed specifically for stratospheric use. Crucially, it operates on the same 3GPP standards as terrestrial base stations (eNodeB for 4G, gNodeB for 5G), meaning a smartphone on the ground cannot tell the difference between a ground tower and Sceye's floating one.
Why Telecom Companies Are Interested
Unlike Starlink satellites, which require specialized antennas, Sceye's system works with standard mobile phones. This has attracted significant commercial interest:
- Sceye is planning two to three commercial tests with multinational telecom companies this year
- SoftBank envisions using HAPS to densify satellite coverage in areas where phones lack the required antenna for direct LEO connections
- HAPS can act as a relay station, receiving traffic from ground users and forwarding it to satellites
The Broader Vision: Meshed Sky-Space Networks
HAPS proponents envision a future network architecture — potentially for 6G or beyond — that meshes three layers:
- Terrestrial — Ground-based cell towers for dense urban coverage
- Stratospheric — HAPS for wide-area coverage and satellite relay
- Space — LEO satellites for global connectivity
Some researchers have proposed mounting HAPS with equipment for edge computing and federated learning, turning them into floating data centers.
Challenges Remaining
- Duration: The record belongs to Airbus's Zephyr at 67 days; Sceye hasn't matched that yet
- Inter-HAPS communication: Multiple platforms serving the same city need to coordinate
- Interference management: Aerial networks must not disrupt traditional cell signals
- Economic viability: Past HAPS projects like Google Loon proved unsustainable commercially
"For HAPS to work in areas where terrestrial base stations do exist, it is really essential to have proper interference management," says Halim Yanikomeroglu of Carleton University.
The technology is coming, but the engineering challenges are far from solved.