Loon, HAPSMobile deliver LTE from fixed-wing aircraft in stratosphere

It’s not every day you get Vint Cerf, known as one of the “Fathers of the Internet,” to join your video call. But when you’re affiliated with Google and doing experimental tests in the stratosphere, maybe that’s par for the course.

Cert, who is VP and chief internet evangelist at Google, was with Jun Murai, known as the “Father of the Internet in Japan” and the external director of SoftBank’s HAPSMobile, for a video call, where they discussed HAPS’ significance for future internet services.

Loon started as a project within Google and graduated to become part of Alphabet. Loon, along with HAPSMobile, on Wednesday announced they successfully tested a jointly developed communications payload in the stratosphere on HAPSMobile’s “Sunglider.” The Sunglider is a solar-powered unmanned aircraft system (UAS).

It was Sunglider’s first stratospheric test flight from Spaceport America in New Mexico, and it took place on September 21, marking the world’s first successful delivery of LTE connectivity from a fixed-wing High Altitude Platform Station (HAPS) autonomous aircraft in the stratosphere, according to the companies.

“Using the stratosphere for the mobile internet is going to be the next most innovative challenge, and it will add to the existing and achieved innovations of the internet,” Murai said in a statement, noting that the connection resulted in a high-resolution call, with smooth video and “practically no latency,” which will be ideal for internet service and disaster recovery in the future.

The test flight used MIMO technology, and the payload enabled LTE connectivity to be delivered continuously for about 15 hours during Sunglider’s flight. Engineers report that it worked as planned, which is saying something – wind speeds at times were greater than 66 mph and temperatures were as low as -73 degrees Celsius (-99 Farenheit).

Notably, they didn’t need special smartphones to do the call. They used the 700 MHz band (LTE Band 28) and a feeder link between the aircraft and a ground gateway using the 70/80 GHz band; engineers were able to use regular smartphones in their video call. 

They collected measurements of stratosphere-to-ground radio wave propagation data that will be used toward future contributions to the ITU Radiocommunication Sector (ITU-R), with an eye toward international standardization. The test also provided insight into how HAPS can be used in disasters and alongside other lifesaving technologies.

RELATED: Alphabet’s Loon partners with Softbank’s HAPSMobile for stratospheric connectivity

HAPSMobile began in 2017 as a joint venture between Softbank and Aerovironment, a U.S.-based aerospace company. The venture developed a solar-powered drone, called Hawk 30, designed to travel in the stratosphere for telecommunications delivery.

A spokesperson told Fierce that all approvals for the test were granted from the relevant authorities, but declined to give details of the specific permits/licenses. 

FCC records show Loon obtained permission earlier this year to evaluate the performance of 700 MHz spectrum from Spaceport America. Loon at that time told the FCC that its experiments involving 700 MHz spectrum complemented ongoing tests already approved by the FCC involving E-band spectrum to interconnect between Loon HAPS balloons and ground terminals.