Wholesale aircraft network ‘will replace hundreds of 5G base

Wholesale aircraft network ‘will replace hundreds of 5G base stations’

03 November 2020 | Alan Burkitt-Gray

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An uncrewed aircraft carrying an advanced antenna can replace 200 conventional mobile base stations, or even up to 700 in some cases.

That was the claim yesterday by development company Cambridge Consultants, which has developed the system in association with aircraft builder Stratospheric Platforms (SPL).

“We’d need 60 aircraft to cover the UK or 67 for Germany,” said Richard Deakin, CEO of SPL.

The two companies are proposing setting up a wholesale operation to run services on behalf of mobile operators, starting from 2024 after the first prototype flies in 2022.

Their high-altitude platform (HAP) will compete with SoftBank’s solar-powered aircraft or the balloon-mounted base stations being operated by Loon, a sister company of Google, with Telkom Kenya in east Africa.

The challenge with those is that solar power runs out after sunset. But SPL’s aircraft will be powered by liquid hydrogen, generating 30kW for the propeller engines and another 20kW for the radio equipment, including millimetre-wave backhaul.

The research is being backed by Deutsche Telekom, which announced a trial in Bavaria in October. Deutsche Telekom is a significant investor in SPL, the company said last month.

A typical array, designed by Cambridge Consultants, would operate in the 2.1GHz and 2.7GHz bands, but they could work anywhere between 900MHz and 3.5GHz, said Deakin.

He and Tim Fowler, chief sales officer of Cambridge Consultants, evaded Capacity’s questions about the capital cost of each aircraft – and whether it was comparable with the cost of the towers it replaced – or the running costs.

“The economics make sense very quickly,” said Deakin, without providing figures.

However, under current rules each uncrewed aircraft has to have a full-time controller, implying at least 180 people would be needed to fly 60 aircraft round the clock.

Cambridge Consultants, owned since April 2020 by Capgemini, has designed a 9sq m antenna with 4,000 elements creating “hundreds of steerable beams”. One aircraft could cover the whole of Greater London, the companies said.

But beams could be controlled to serve a linear structure such as a road or even to point at a single vehicle. “We’ve tested it at the highest throughput that cellular standards support,” said Fowler.

Aircraft will fly for nine days at 20km above the ground before they need to return for refueling, said Deakin.

Cambridge Consultants and SPL hailed the scheme as a way of speeding up 5G installation – though critics at an online presentation last night pointed out that much of western Europe’s 5G networks will have been built by 2024. “The UK needs another 400,000 5G masts,” said Deakin.

The two companies are proposing “setting up as a small airline” to run the fleet of aircraft, each of which will have a design life of ten years, said Deakin.

Base stations in the air will be able to deliver speeds of up to 100Mbps to handsets. “The challenge is to carry 100Gbps of aggregate traffic,” he said.

Aircraft will be able to operate with 10km horizontal separation, said Deakin, a former CEO of the UK’s air navigation operator National Air Traffic Services (NATS), and 1,000ft (300m) vertical separation.

One of the challenges the two companies face over the next few years is designing the cooling for 50kW of power generation, including 20kW emerging from the antenna, especially in the thin air at 20km up. “We haven’t taken the antenna into the stratosphere yet,” admitted Fowler.