The balloon-based Loon project, which grew out of an experimental division of Google’s parent company, Alphabet, recently applied for FCC permission to expand its testing of LTE bands 20 and 28 near its facility in Nevada, with an eye toward delivering commercial service and expanding internet access to underserved areas.
“Loon will ... be using ordinary, FCC approved handsets to communicate with the balloons, and then Wi-Fi (used in conjunction with Part 15 unlicensed Wi-Fi ) or the E-band frequencies ... to interconnect with the ground terminals,” the company wrote in its application.
The company plans to deliver its first commercial service based on the Loon project next year in Africa.
“Loon recently graduated from X to become an independent business within Alphabet and will begin providing commercial service to parts of Kenya in 2019,” the company said in an emailed statement. “We continue to test and refine our system in Nevada--where we have a launch site--as we prepare for that deployment.”
According to the company, the experiment will shut down transmissions if the GPS-connected platforms move out of the test area.
“If the receiver detects that the platform has exited the test area, it will automatically disable transmissions over the test frequencies,” according to the application. “Connections to the ground infrastructure can be used to manually disable transmissions. [T]he airborne radios will automatically be disabled if connection to the ground infrastructure is lost for a defined period of time.”
The Loon project's polyethylene flight balloons are, as the company describes them, “tennis court-sized” and rise to the stratosphere about 12.4 miles above the Earth’s surface. Attached to the balloon is an LTE antenna that connects to a user’s phone or a ground station.
Solar panels keep the equipment powered during the day and charge a battery for use at night. A flight capsule holds the computer systems to control the balloons, which are built to withstand stratospheric conditions for up to 100 days. A parachute assists the balloon in landing land when its mission is over.
Part of the appeal of the Loon project's stratospheric antennas is that they can provide access to a much larger area than traditional cell towers, which are limited by their height.
Along with providing coverage gaps to underserved and remote areas, Loon’s technology can be used to quickly provide Internet access after natural disasters. After Hurricane Maria in Puerto Rico, Loon provided LTE internet access via T-Mobile and AT&T to as many as 250,000 people.
The company launched balloons from its Nevada facility and navigated them to Puerto Rico by pumping air into or out of inner balloon, which makes the outer balloons rise or fall.
The balloons catch winds in the stratosphere moving in the direction they need to go. “This ‘go-with-the-flow’ technique allows the balloons to quickly and efficiently get in the right spot,” the company says. “Winds in the stratosphere are stratified, which means they’re comprised of layers that travel in different directions and speeds. While one layer may cause the balloon to drift far from its target location, another nearby layer might allow the balloon to blow in the right direction.”
Loon maps these wind patterns using models to predict wind speed, direction at various times and locations. Algorithms help find the quickest path to a destination, and how to stay clustered where they need to remain.
The team also created “autolaunchers,” which can fill balloons and launch them--“flying every 30 minutes,” the company says, “into the stratosphere, above airplanes, birds, and the weather.”