• DT reveals strategic investment in UK startup developing hydrogen-powered, remote-controlled aircraft to deliver broadband connectivity.
  • Operator takes on Alphabet, SoftBank, and SpaceX with rival system in the stratosphere.

Deutsche Telekom demos flying base stations in stratosphere

Deutsche Telekom demos flying base stations in stratosphere

Source: University of York

Deutsche Telekom (DT) formally unveiled a strategic partnership with UK-based Stratospheric Platforms (SPL) and demonstrated LTE services delivered from a hydrogen fuel-cell powered, remote controlled aircraft, claiming the first integration with a live terrestrial cellular network and staking its ambitions in the High Altitude Platform Station (HAPS) market.

TelcoTitans first reported in March 2019 that DT’s Telekom Innovation Pool (TIP) had taken a 31% stake in SPL, as part of a long-running R&D tie-up (Deutsche Telekomwatch, #81), and the companies revealed today that they have been quietly developing the stratospheric technology platform for the last five years.

Strategically, Deutsche Telekom Chief Executive (CEO) Timotheus Höttges referred to the work with SPL as a “Horizon 3” (long-term) or “even Horizon 4” project aimed at complementing its existing fixed and mobile networks to provide broadband services in so-called “white spots”, and eventually achieve ubiquitous data coverage. He said the technology might go live in the next five or ten years, “depending on how fast we get all the approvals”.

Taking aim at rival stratosphere initiatives, Höttges positioned SPL’s system as an “alternative to SpaceX and other services”, and that the partners had gone “one step further than Alphabet or SoftBank in what we have developed”, referring to the companies’ Loon and HAPSMobile ventures, respectively.

This technology has significant advantages over balloon and satellite”, he said. “I’m sure that we have found a very interesting alternative for ubiquitous data coverage for everybody”.

Compared to solar-powered aircraft, SPL’s hydrogen fuel-cell powered planes can carry heavier loads, which means they can haul bigger and more powerful antennas. Also, remote-controlled aircraft can be “steered much more precisely than stratospheric balloons”, he said.

Höttges hinted at bigger plans for the partnership beyond DT’s own network services in Europe, noting that the companies are researching the creation of a “stratospheric network” and that there are other parts of the world that also need broadband coverage solutions. “We are opening it up as an opportunity for others to look into”, he said.

Delivering broadband from the sky

In October in Bavaria, DT and SPL tested voice and data services delivered from LTE antennas on a remoted-controlled aircraft flying at about a 14km altitude. The aircraft can cover areas with a diameter of up to 140km. Using a standard smartphone, the partners demonstrated voice and video calls, data downloads, and web browsing over the network. The test hit download speeds of 70Mbps and upload speeds of 20Mbps, using DT’s 2.1GHz spectrum.

The test is said to have marked the first time a terrestrial cellular network was integrated with an antenna in the stratosphere.

SPL is new kid in the stratosphere

Richard Deakin, CEO of SPL, based in Cambridge, said that the first production aircraft will be ready in 2022 and as the operational infrastructure is being built, the target for operational deployment is 2024. SPL plans to build a factory to produce 200 planes per year.

The startup said it is in talks with investors regarding a Series-B funding round, which would reportedly raise £50m (€43m), according to Reuters. In addition to DT, SPL partners include Bombardier Belfast, Cambridge Consultants, Northrop Grumman, QinetiQ, and Thales. “We’re thrilled to be working with DeutscheTelekom to realise our vision of providing true broadband connectivity, from the sky, and we welcome other investors to join us on this journey to cost-effectively address the challenges of broadband [rollout]”, Deakin said.

Companies with high-flying ambitions for mobile connectivity
CompanyHAPS vehicleStatus

Sources: companies.


Zephyr solar-powered unmanned aircraft.

Aircraft production facility opened in 2018.


(subsidiary of Alphabet)

Stratospheric balloons.

Commercially operational in Kenya (with Telkom Kenya); launch planned for Mozambique (with Vodacom).


(subsidiary of SoftBank)

Sunglider solar-powered unmanned aircraft.

Commercial service launch targeted for 2023.


Hydrogen fuel-cell powered unmanned aircraft.

Operational deployment planned for 2024.

DT has eye on the sky

DT has for several years been visibly interested in aviation technology as a driver of its Integrated Networks Strategy, pushing in-flight broadband services through its European Aviation Network partnership with Inmarsat, and tying with Airbus to explore edge-based media-sharing platforms for aircraft passengers (Deutsche Telekomwatch, #78).

Through prolific corporate investment arm Deutsche Telekom Capital Partners, which manages TIP, the telco has also been increasingly channelling financial backing to challenger vendors that promise to disrupt operators’ supply chains and reduce procurement costs. As well as Stratospheric Platforms, DT has invested in network infrastructure upstarts Affirmed Networks (which was acquired by Microsoft in April 2020), BENOCS, and Rtbrick, among others.