SoftBank’s HAPSMobile and Alphabet’s Loon announced a successful trial of their jointly developed communications payload in the stratosphere on an unmanned aircraft system (UAS), as a partnership between the pair struck last year begins to gather momentum.

In a statement, the companies claimed the test marked the world’s first successful delivery of LTE connectivity from a fixed-wing High Altitude Platform Station (HAPS) autonomous aircraft in the stratosphere.

The test, powered by MIMO technology, saw the payload enable 4G connectivity to be delivered continuously for approximately 15 hours on HAPSMobile’s solar powered Sunglider UAS.

The duo also claimed it was also completed under “demanding conditions,” as wind speeds reached approximately 30 metres per second and temperatures were as low as -73 degrees Celsius.

During the test, the communications payload enabled a video call between both sets of team members. The test system was composed of a service link from Sunglider using the 700MHz spectrum band, and a feeder link between the aircraft and ground gateway using mmWave spectrum, added the statement.

Junichi Miyakawa, president and CEO of HAPSMobile, said the test enabled the companies to obtain “vital data that will accelerate the development of commercial services and improve the coverage and quality of our HAPS connectivity.”

HAPSMobile invested $125 million in Loon in April 2019, as the pair signed an agreement to jointly explore commercial collaborations to accelerate the deployment of high-altitude connectivity systems.

News of the successful trial comes days before both companies are set to appear on a Mobile World Live webinar looking at mobile network infrastructure for the next era, as part of our next Themed Week focused on ‘Connecting the Next 4 Billion.’