Alphabet’s laser-Internet system has sent 700TB of data with 99.9% uptime

Google’s parent company, Alphabet, is still experimenting with hooking up remote towns to the Internet via frickin’ laser beams. Today, Alphabet’s moonshot “X Lab” shared an update on Project Taara, its experimental point-to-point optical communication system, often described as “fiber optics without the fiber.” The company built a working installation in Africa and has been blasting a 20Gbps link about 5 km across the Congo River to a town of millions of people, lowering the cost of Internet access for them.

The Taara 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 sides of the Congo River. Brazzaville has decent Internet, but because nobody wanted to run a fiber line through the world’s deepest and second-fastest river, Kinshasa uses a fiber line that runs 400 km around the river, and the Internet is five times more expensive there. Alphabet’s 20Gbps commercial link has been up and running for 20 days now, and the company says it has served nearly 700TB of data in that time, with 99.9 percent uptime.

Taara was born out of the “Loon” Internet balloon project launched in 2017. Originally, Google was building flying cell towers to beam down the Internet from the sky (over RF), but for balloon-to-balloon backhaul, the company was planning communications via laser beam. Space X just started doing something similar by equipping its Starlink satellites with space lasers for optical intra-satellite communication. One benefit of Sky- and space-based laser communication is that not much can interfere with a point-to-point optical beam. Ground-based lasers have more interference to consider, since they have to deal with nearly everything: rain, fog, birds, and once, according to Alphabet’s blog post, “a curious monkey.”

Much of the Taara project has been about solving all of these ground-based interference problems. Taara blasts a laser down into a 45-degree mirror, resulting in a laser that makes a 90-degree turn and fires out of the front lens. The mirror is movable, allowing both ends of Taara to make small adjustments. Alphabet says, “To create a link, Taara’s terminals search for each other, detect the other’s beam of light, and lock in like a handshake to create a high-bandwidth connection.” With adjustable beams, Alphabet says it has been able to handle haze, light rain, and birds without a 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 in the gaps where faster, more reliable methods (like fiber) aren’t feasible. With the 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, red here is good and indicates that Alphabet expects to hit 99 percent uptime with a link in that area.

https://arstechnica.com/?p=1795716