Google’s parent company, Alphabet, is still experimenting with frickin’ laser beams to connect remote cities to the Internet. Today, Alphabet’s Moonlight “X Lab” shared an update On Project Tara, its experimental point-to-point optical communication system, often described as “fiber optics without fiber”. The company built a working installation in Africa and is destroying a 5km 20Gbps link across the Congo River to a city of millions, reducing the cost of internet access for them.
The STAR laser beam is bridging the gap between Brazzaville in the Republic of the Congo and Kinshasa in the Democratic Republic of the Congo, which are on opposite banks of the Congo River. Brazzaville has good internet, but because no one wanted to run a fiber line through the world’s deepest and second fastest river, Kinshasa uses a 400 km fiber line. Everywhere river, and the Internet is five times more expensive there. Alphabet’s 20Gbps commercial link has been running for 20 days now and the company says it has served about 700TB of data in that time, with a 99.9 percent uptime.
Tara was born out of the “Loon” internet balloon project launched in 2017. Originally, Google was building flying cell towers to beam the Internet from the sky (over RF), but for balloon-to-balloon backhaul, the company was planning. Communication via laser beam. SpaceX started doing something similar by equipping its Starlink satellites space laser For optical intra-satellite communication. One advantage of sky- and space-based laser communications is that not much can interfere with the point-to-point optical beam. Ground-based lasers have more interference to consider, because they have to deal with almost everything: rain, fog, birds, and once, according to Alphabet’s blog post, “a curious monkey.”
Much of the Tara project is about solving all these on-the-ground intervention problems. The star shoots a laser down into a 45-degree mirror, resulting in a laser that makes a 90-degree turn and exits the front lens. The mirror is movable, allowing small adjustments to be made to both ends of the star. “To form a link, the star’s terminals seek out each other, detect the other’s beam of light, and lock like a handshake to form a high-bandwidth connection,” Alphabet says. With the adjustable beam, Alphabet says it’s able to handle fog, light rain, and birdsong without service interruption.
Like every other method of Internet connectivity, Alphabet says wireless optical communication isn’t a one-size-fits-all solution, but it can fill gaps where faster, more reliable methods (like fiber) aren’t possible. With local weather being a primary interference factor, the company has produced a color-coded world map where it says the technology will be viable. Oddly enough, here’s red Good And indicates that Alphabet expects to hit 99 percent uptime with a link in that area.