Japan’s next telecommunications network could extend far beyond conventional cell towers. SoftBank has signed a five-year agreement with US aerospace company Sceye to build a stratospheric network of high-altitude platforms, with the goal of providing nationwide mobile coverage. The planned fleet would operate between terrestrial infrastructure and orbiting satellites, adding another layer to Japan’s communications systems. The agreement covers the manufacturing, launch, and operation of Sceye’s High Altitude Platform Systems (HAPS). Most of the initial fleet will provide mobile broadband, while selected platforms will support free-space optical communications, using laser links to transmit data through the atmosphere. For eeNews Europe readers, the agreement offers a glimpse of how future mobile networks could extend beyond terrestrial infrastructure. Combining airborne base stations, optical links, and onboard edge computing could improve coverage in remote areas while providing additional communications capacity during natural disasters. Cell Towers Operating in the Stratosphere Unlike conventional satellites, HAPS operate within the Earth’s atmosphere and are designed to remain over a particular region for extended periods. Sceye’s platforms maintain their operating altitude and position through successive day and night cycles, allowing them to provide communications services without relying on terrestrial towers at every location. The company’s SceyeCell system effectively functions as an airborne cellular base station, transmitting mobile signals directly to standard devices on the ground. During a 30-day test mission in 2026, a Sceye platform traveled from New Mexico to Japan and back. While operating over Japan, the companies demonstrated voice calls, text messaging, internet access, and video streaming. The tests also covered indoor connectivity, emergency communications, remote drone control, and edge computing performed aboard the platform. These demonstrations provide a technical basis for the planned commercial deployment, although the companies have not disclosed the number of platforms required for nationwide coverage or a timetable for achieving it. Laser Links for Future 6G Networks The agreement goes beyond extending conventional mobile coverage. A portion of Sceye’s fleet will establish a free-space optical network in the stratosphere. Rather than using radio frequencies for every connection, optical links could provide high-capacity data transmission between airborne platforms and other network infrastructure. The companies also demonstrated ground-based laser ranging of a HAPS during their test campaign, an important step toward future optical communications involving ground stations, stratospheric platforms, and satellites. SoftBank intends to incorporate HAPS into its Ubiquitous Network strategy, which aims to connect terrestrial, airborne, and satellite communications infrastructure. “This agreement represents the commercialization of HAPS and the realization of our vision for Ubiquitous Transformation,” said Masayuki Kamimura, Senior Director of SoftBank’s Ubiquitous Network Planning Division. From Demonstrations to Commercial Deployment The five-year agreement moves the partnership toward fleet manufacturing and commercial operations. SoftBank previously invested in Sceye during the company’s Series C funding round in 2025. Sceye is now preparing to scale production of its stratospheric platforms, although neither company has announced the fleet size or financial terms of the agreement. The planned network could eventually support applications ranging from emergency communications and IoT connectivity to aerial services and distributed computing. For SoftBank, the objective is to make stratospheric connectivity a permanent part of Japan’s telecommunications infrastructure, adding another layer of coverage between ground-based networks and satellites. The post SoftBank and Sceye Plan Stratospheric Netw