5G blue overlay over a grounded plane
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BT Group, the largest broadband and mobile services company in the U.K., partnered with Stratospheric Platforms Ltd. to test mobile coverage enabled by a high-altitude platform station aircraft, BT Group announced on Jan. 30. It’s a proposed solution to difficulties with 4G and 5G connectivity in remote areas of the U.K.

A new antennae format enables the experiment — the testing of which has begun at BT Group’s global research and development headquarters at Adastral Park in Ipswich, U.K.

The key to this 5G connectivity: A phased array antenna

SPL’s phased array antenna can deliver up to 150Mbps across areas as wide as 140 km or 15,000 square km, the organization claims. It uses 500 individually steerable beams mounted on the aerial platform. Essentially, each beam is equivalent to a cell created by traditional terrestrial masts for LTE and 5G smartphone signals. The antenna is three meters in diameter and uses 20kW of power.

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That aerial platform is SPL’s pride and joy: a hydrogen-powered, autonomous plane that will take to the stratosphere for a week at a time. Mounting the equipment on the aircraft will reduce the need for ground-based infrastructure, SPL explained.

Although the plan is eventually to position the payload on the aircraft, for now, the antenna is in place on a tall building. There, both companies will test how it integrates with BT Group’s 5G secure architecture, connecting with its Open RAN testbed. They’ll make sure it can support multiple user groups and different potential use cases at the same time on the same network.

By using hydrogen fuel, SPL wants to be a greener alternative, too. In a study commissioned by SPL, they proposed the aircraft solution could save 0.45 million tons of carbon dioxide per year by replacing and decommissioning existing cell tower sites.

SPL’s aircraft follows in the lineage of Facebook’s internet-transmitting planes. The tech giant shuttered its solar-powered Aquila plane, which was similarly intended to transmit internet into areas hard to reach with traditional infrastructure, in 2018. In essence, it just wasn’t practical; although, the plane itself worked well enough.

Use cases for day-to-day and emergencies

With cell signals in the U.K. notoriously spotty, SPL and BT Group have a bevy of everyday connectivity problems, which their partnership could potentially solve. BT Group wants to extend existing U.K. cellular infrastructure as well as provide a possible backup for emergencies.

The aircraft could spend some of its time helping out with disaster relief and supporting humanitarian aid. BT Group also suggests the mobile platform could be used for “remote monitoring across various industrial and agricultural use cases, improving efficiency of operation.”

The focus, though, is still on reaching remote or hard-to-cover areas in the U.K. for daily operation, ensuring customers have reliable 4G and 5G connectivity at what is considered the modern standard of speed and convenience.

“This highly innovative and transformative project has the potential to further enhance our U.K. 4G and 5G footprint … to connect unserved rural areas and enable exciting new use cases for private users,” said Tim Whitley, managing director research and network strategy at BT Group.

SPL CEO Richard Deakin shares Whitley’s excitement for the U.K.-developed technology, claiming SPL’s partnership with BT Group will continue past their successful “world-first 5G demonstration from the stratosphere achieved in 2022.”

Eyes in the sky: SPL aerial transmissions

While both organizations are based in the U.K., SPL is backed by Europe’s largest operator Deutsche Telekom. Since its founding in 2014, SPL has been working on 5G transmission from the sky.

In March 2022 it operated a 5G signal with a download speed of 90Mbps from a 45,000-foot flight. That flight, performed in collaboration with the Saudi Communications and Information Technology Commission, demonstrated the antenna’s use in transmitting between the local telecoms network, a 5G base station, the flying stratospheric antenna and retail mobile devices.

SPL claims it was able to stream 4K video to a mobile phone with an average latency of one millisecond above network speed in tests conducted on land and from a helicopter.

BT Group’s cloud transition

In other news from BT Group, its Digital Unit will transition mainframe applications to the cloud in a partnership with Kyndryl, the company which had already been in place managing the mainframe estate. Specifically, it will move applications that serve BT Group’s legacy copper business and consumer broadband products.

The 10-year partnership will involve some applications being retired, some being integrated into other parts of BT Group’s existing strategic systems and architecture, and some shifted to the cloud environment. The modernization will also include the addition of application programming interfaces and microservices capabilities.

BT Group and Kyndryl propose that the shift will reduce mainframe operating costs and energy consumption by 70%, leading to savings worth more than £17 million ($20.98 million USD) a year by 2026.

“We like thinking out of the box to solve complex problems — like how to move off mainframes given the prohibitive increase in legacy infrastructure cost — without rewriting decades-old applications,” explained Harmeen Mehta, chief digital and innovation officer at BT Group. “With that mindset, working with Kyndryl, we figured out how to turn legacy mainframes into modern digital apps and run them at a fraction of the cost.”

This is part of a larger effort by BT Group to adapt to an artificial intelligence-led operations model.

“Migrating from mainframes to cloud extends the usefulness and lifespan of these applications in a modern, microservices-led, cloud-centric way and helps unlock intelligent data insights,” said Petra Goude, global practice leader for core enterprise and zCloud at Kyndryl.

Elsewhere in connectivity, see 5G trends to watch in 2023, the security risks of 5G and how 5G influences AR and VR.