SoftBank Prepares First HAPS Connectivity Trial Over Japan
SoftBank is preparing to conduct its first High Altitude Platform Station (HAPS) flight and direct-to-device connectivity trial over Japan this summer, a milestone in its nearly decade-long effort to commercialise stratospheric communications as part of its broader non-terrestrial network (NTN) strategy.
The trial will use a lighter-than-air HAPS platform developed by U.S. partner Sceye, operating at an altitude of approximately 20 kilometres. Unlike satellite-based direct-to-device services, SoftBank says HAPS is designed to deliver higher-capacity, lower-latency connectivity comparable to terrestrial mobile networks, making it suitable for disaster recovery, rural coverage and future aerial mobility applications.
Ahead of the Japanese trial, Sceye successfully completed a 12-day stratospheric flight from New Mexico, covering more than 10,300 kilometres before concluding its mission over the Atlantic Ocean. SoftBank also completed end-to-end testing between HAPS communications equipment and its mobile core network, successfully validating voice, SMS and data services using a standard SoftBank smartphone.
To support the trial, SoftBank has installed a ground gateway in Kochi Prefecture that will automatically track the HAPS platform and connect it to the operator's terrestrial core network. Once Sceye's aircraft reaches Japan, SoftBank plans to conduct connectivity demonstrations in simulated disaster environments across regions including Kochi, Kinki, Kyushu and Tohoku.
The trial has three primary objectives:
Validate HAPS flight performance under Japan's environmental and weather conditions.
Demonstrate voice, SMS and data services with performance comparable to terrestrial mobile networks.
Assess potential radio interference between HAPS and existing terrestrial mobile infrastructure.
SoftBank views HAPS as a complementary technology to its recently launched SoftBank Starlink Direct service. While Starlink Direct is intended to provide basic connectivity in areas without cellular coverage, HAPS is being positioned as a higher-capacity platform capable of supporting broadband services and rapidly restoring communications after natural disasters.
Looking beyond the initial trial, SoftBank plans to begin commercial HAPS services from 2027 onwards. The company ultimately envisions integrating HAPS with low Earth orbit satellites through optical inter-satellite links to create a multi-layered "3D communications network" supporting future AI-enabled services, autonomous mobility and ubiquitous connectivity across terrestrial and non-terrestrial networks.