BT has partnered with Stratospheric Platforms (SPL) to trial delivering 5G connectivity from a High-Altitude Platform Station (HAPS) aircraft. The collaboration aims to address a persistent challenge in mobile coverage: reaching rural and hard-to-access locations with reliable broadband.
The programme will test new airborne antenna technology mounted on SPL’s HAPS to beam 4G and 5G signals from the stratosphere. If successful, the approach could extend commercial mobile coverage across vast, sparsely populated regions where traditional ground infrastructure is costly or impractical to deploy.
“We’re delighted to be partnering with SPL to start realising the huge potential of HAPS aircraft to further strengthen our UK 4G and 5G network technology leadership,” said Tim Whitley, Managing Director of Research and Network Strategy at BT. He added that the technology could enhance BT’s existing mobile footprint, helping to connect unserved rural communities and enable new private use cases.
SPL’s phased-array antenna is designed to steer 500 independent beams, delivering peak speeds up to 150 Mbps across coverage footprints as large as 140 km in diameter or roughly 15,000 km2. Both the antenna system and the flight platform are hydrogen-powered to reduce operating costs and improve sustainability.
Richard Deakin, CEO of SPL, said the partnership will build on the company’s earlier achievements. In 2022 SPL demonstrated a 5G signal beamed from the stratosphere, operating for five hours at an altitude of 45,000 ft and achieving download speeds around 90 Mbps. That test showed that an airborne 5G mast can provide stable broadband across extensive areas and perform comparably to terrestrial mobile networks.
SPL is developing a hydrogen-powered “Stratomast” HAPS expected to remain airborne for up to a week without refuelling, covering approximately 15,000 km2 with a single antenna. The longer endurance and wide-area coverage make HAPS a promising complement to satellites and ground stations, particularly for temporary events, disaster response and underserved regions.
Potential applications for HAPS-delivered connectivity include search and rescue operations, humanitarian aid coordination, maritime security, and improving consumer mobile access in remote communities. The flexibility of airborne platforms also means operators can quickly reposition coverage where demand arises or where ground infrastructure has been damaged.
The BT–SPL trials are supported in part by Innovate UK and will take place at BT’s global research and development campus at Adastral Park in Suffolk. The tests will focus on real-world performance, integration with existing mobile networks, and the operational practicality of hydrogen-powered stratospheric platforms.
This collaboration represents a step toward diversifying how mobile networks deliver connectivity beyond traditional towers and satellites, exploring a middle layer in the skies that combines wide coverage, lower latency than many satellites, and the potential for more cost-effective deployment in remote territories.
(Image Credit: BT)