Deutsche Telekom-backed venture seeks to replace 5G masts with aircraft

Cambridge Consultants and its partner Stratospheric Platforms Limited (SPL) are claiming a breakthrough in the antenna technology that Cambridge developed for SPL’s system for replacing 5G infrastructure on the ground with airborne cell towers.

SPL is working to develop a system that will replace masts on the ground with unmanned aircraft, which are essentially flying cell towers. SPL, which also is headquartered in Cambridge, U.K., is developing a High-Altitude Platform (HAP) and communications system operating in the stratosphere.  

The rollout of 4G/LTE was slow and expensive in the U.K., and with the move to 5G, it’s estimated that an additional 400,000 masts will be needed to cover the U.K., so if the aircraft can replace hundreds of masts, the economics works out very quickly, said SPL CEO Richard Deakin during a media briefing on Monday.

Depending on how many back-up aircraft are used, about 60 aircraft could cover the U.K. Each aircraft can replace at least 200 masts, depending on the configuration, a huge benefit over the installation of masts across the country, Deakin said.

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Operators in Europe already are deploying 5G, and this system is complementary to what they’re doing, he said. The plan is for commercial operations to begin in Germany in 2024; it’s been working with Deutsche Telekom on potential rollouts, according to Deakin. DT holds a 38% stake of SPL.

SPL is targeting the same market as some other initiatives in the stratosphere, including Loon’s balloons that are connecting people in remote areas of the world. Like Loon, SPL is working to team up with established mobile operators on the ground. DT has exclusive licenses to operate the SPL technology, when commercially deployable, in 18 countries around the world. 

Cambridge marks breakthrough

The antenna is at the heart of the system, which is where Cambridge Consultants comes in. A team of about 90 people worked on the project, which had to be kept confidential for about four years. Cambridge Consultants is part of Capgemini Group.

One of the challenges was making the antennas that are able to transmit to regular handsets on the ground, according to Tim Fowler, chief sales officer at Cambridge Consultants.  

They needed something big and powerful but light and power efficient, he said. What they developed is a modular approach. Each antenna produces 480 individual, steerable beams, creating patterns that can be “painted” onto the ground to cover specific areas like roads, railways lines or shipping lanes.

According to Cambridge, the ability to produce hundreds of beams enables the antenna to reuse spectrum, ensuring fast and even coverage across the area. The digital beamforming capability allows for flexibility in how services are deployed and allow in-flight reconfiguration to deliver services beyond the reach of traditional fixed terrestrial networks.

Last month, Deutsche Telekom and SPL announced they had conducted a successful demonstration of LTE/4G voice and data connectivity over a platform flying at the edge of the stratosphere and fully integrated into a commercial mobile network. Several test flights were done in Bavaria with a remote-controlled aircraft system using 2.1 GHz.

The tests enabled voice over LTE (VoLTE) calls, video calls, data downloads and web browsing on a standard smartphone. The smartphone was connected to the terrestrial mobile network of Telekom Deutschland via the antennas on the aircraft. The test showed download speeds of 70 Mbps and upload speeds of 20 Mbps over a channel bandwidth of 10 MHz.

SPL at the time said it’s working with other partners on the development of the hydrogen-powered, remote-controlled aircraft, the associated communications payload and related ground-based infrastructure as well as orchestrating the production and service partner ecosystem required for commercial deployment.