Alphabet and SoftBank subsidiaries Loon and HAPSMobile stated high-altitude aircraft were now ready to challenge terrestrial mobile networks after beaming a stable 4G signal from the atmosphere to smartphones.

In a statement, HAPSMobile president and CEO Junichi Miyakawa said the achievement was “an important step forward in our efforts to realise stratosphere-based communications and promote the adoption” of High Altitude Platform Stations (HAPS).

“In partnership with Loon, we will continue to develop technologies for HAPS with the aim of revolutionising the world’s mobile networks.”

Loon CEO Alastair Westgarth added: “The stratosphere represents an untapped area of opportunity when it comes to expanding connectivity.”

A communications payload used in Loon’s helium balloons was adapted and attached to HAPSMobile’s HAWK30 aircraft, a solar-powered autonomous drone, enabling 4G connectivity with data rates of up 1Gb/s over a maximum distance of 700km.

The payload was modified to cope with the 100km/h velocity of the HAWK30.

In recent testing, Loon established and maintained a connection using the technology in 20 balloons to cover an area of more than 4,000km.

HAPSMobile invested $125 million into Loon as part of a partnership agreed in April 2019 to promote use of high altitude communications systems.