Testing Stratospheric Connectivity
SoftBank and US aerospace firm Sceye finished a major High Altitude Platform Station (HAPS) communications trial in Japan this August. This test marks a milestone in the operator's push to launch commercial HAPS services by 2027. The project involved a lighter-than-air platform moving from New Mexico to Japan, covering 15,000 kilometers over 13 days before reaching Muroto City in Kochi Prefecture.
During the trial, the HAPS maintained a stable position at an altitude of 16.5 kilometers. It functioned as a 4G LTE base station, linking directly to a ground gateway in SoftBank’s core network. The team successfully verified voice, text, and data transmission between the stratospheric platform and ground devices. They even completed a test call to the Japan Coast Guard’s 118 emergency maritime number to prove the system can handle critical alerts during natural disasters.
Advancing Edge Computing in the Sky
SoftBank installed mobile core network functions and a web server directly onto the platform for this test. By shifting processing to the stratosphere, the team eliminated the need to route traffic back to terrestrial cloud servers. This setup produced a round-trip latency of 68 milliseconds. That result beats standard internet-based cloud processing by more than 40 percent.
This experiment represents a shift in how network architecture is designed for aerial stations. It keeps data local to the point of origin, which is crucial for remote or disaster-hit areas where terrestrial infrastructure fails. The company confirmed that this is the first time a mobile core and web server have been combined for onboard processing in a HAPS flight.
Future Integration with Satellite Networks
SoftBank began its HAPS development work in 2017. Their roadmap includes building a three-layered network that links the ground, the sky, and space. To realize this, the operator is collaborating with the National Institute of Information and Communications Technology, ArkEdge Space, and Kiyohara Optics on optical inter-satellite links. They plan to test bidirectional optical communication between a HAPS unit and a low-Earth orbit satellite in 2027.
These optical links aim for data speeds reaching 10Gbps across distances up to 2,000 kilometers. The data collected from the recent Sceye trial will shape the operating procedures for these future commercial services. The company remains focused on solving coverage gaps in mountainous regions and islands through this stratospheric infrastructure.