System relies on millimeter-wave-based backhaul to communicate with the ground and other UAS
Japanese tech giant Softbank and Alphabet’s Loon have taken another step in establishing communications links based on unmanned aircraft system (UAS) flying in the earth’s stratosphere.
The two companies said recently that they have successfully developed a communications payload for HAPSMobile’s Hawk30, which is a solar-powered unmanned aircraft system designed to fly in the stratosphere, that enables the drone to “serve as a stratospheric cell tower.”
Softbank and Loon agreed last April to explore High-Altitude Platform Station (HAPS, sometimes also referred to as High-Altitude Pseudo Satellites) together, which resulted in a $125 million investment in Loon by HAPSMobile, Softbank’s subsidiary focused on developing solar-powered UAS for HAPS-based connectivity.
The partnership between Loon and Softbank “grew out of a joint recognition of the untapped potential of the stratosphere to enhance the connectivity ecosystem and bring more people, places, and things online,” according to the companies. At the time of the announcement last spring, Loon CEO Alastair Westgarth said that his company saw working with Softbank and HAPSMobile as “an opportunity to develop an entire industry, one which holds the promise to bring connectivity to parts of the world no one thought possible” and categorized the partnership as “the beginning of a long-term relationship based on a shared vision for expanding connectivity to those who need it.”
Since then, technical teams from Loon and Softbank have been working on adapting the communications set-ups for Loon’s stratospheric balloons for the Hawk30, and now they say they’ve done it.
The two companies said that the effort leveraged Loon’s expertise in building communications systems that could withstand the tough conditions of the stratosphere, where temperatures can be as low as -90 degrees Celsius and winds can reach speeds of 100 kilometers on hour.
To date, Loon says it has flown more than 40 million kilometers and connected over 300,000 people with its balloon-based stratospheric system, which has been used in disaster response and recovery in locations such as Puerto Rico. In recent testing, Loons says it established and maintained a connection among 20 balloons spanning an area of more than 4,000 kilometers. But Loon’s balloons travel much more slowly than the flight speeds of the Hawk30, which is designed to fly at speeds of more than 100 km/h, so the communications equipment that it would carry had to be adapted.
The communications system for the UAS has millimeter-wave-based backhaul links that “connect the vehicle to a physical internet access point on the ground, and allow multiple vehicles to connect with one another in the stratosphere” via “highly accurate antennas that are capable of establishing point-to-point connections at distances of up to 700 kilometers and carrying data at speeds up to 1 Gbps,” according to Loon and Softbank. The antennas rotate as the UAS move, in order to keep a stable connection.
According to the two companies, software improvements as part of the adaptation for the UAS “allow the antenna to rotate more quickly and track more rapid movements. Additionally, the team developed an aerodynamic housing to protect the antennas from the forces brought on by increased flight velocity.”
The payload also has a “custom-designed LTE system that operates on various 3GPP-compliant frequency bands,” the companies added, which means the drone can provide LTE connectivity for standard LTE smartphones or other LTE-enabled devices.
“In combination with the millimeter wave communication system, the Loon payload is able to serve the internet to a large number of smartphone users at a long distance from existing ground infrastructure,” according to Loon and Softbank.
Sprint, which is owned by Softbank, has also supported the development, lending special access to its 1.9 GHz and 2.5 GHz spectrum in Hawaii to HAPSMobile for testing drone-based LTE links. HAPSMobile has also worked with Facebook on test flights, including one in South Africa that utilized a general aviation airplane outfitted with a communications system from Facebook that used 26 GHz and 38 GHz spectrum, flying at an altitude of 4 kilometers.
“This is an important step in our partnership with HAPSMobile. The stratosphere represents an untapped area of opportunity when it comes to expanding connectivity,” said Loon’s Westgarth. “Loon is working to leverage our significant experience building and operating stratospheric technology to develop a new layer of connectivity that will fill the gaps between ground-based and space-based systems. With HAPSMobile, we’ve found a partner who shares our enthusiasm for this new frontier. We look forward to continuing to work together to develop this new industry and connect people everywhere to the benefits of the internet.”
Junichi Miyakawa, representative director and CTO of SoftBank who also serves as president and CEO of HAPSMobile, said that Softbank is “very pleased that our strategic relationship with Loon is already bearing fruit. Our jointly developed communications payload represents an important step forward in our efforts to realize stratosphere-based communications and promote the adoption of HAPS.”