Alphabets Taara sent 700TB via lasers across Congo River during test

In a test of laser communications in the Republic of Congo and the Democratic Republic of Congo, Alphabet’s Project Taara transported nearly 700TB of data in 20 days between Brazzaville and Kinshasa, the two capitals separated by the Congo River.

The uptime of the laser link that Project Taara established between Brazzaville and Kinshasa was 99.9 percent, Alphabet reports. The two capitals are 3 miles apart, one in the Republic of the Congo, the other in the Democratic Republic of the Congo. However, according to Alphabet, internet in Kinshasa is five times as expensive as in Brazzaville because the fiber connection from Brazzaville has to be diverted 400 kilometers thanks to the wide Congo River in between.

The project is therefore testing the use of laser-based optical communication to bridge the distance and set up a broadband connection. The technique that Taara uses is capable of achieving a bandwidth of 20 Gbit/s and a single link has a range of 20 kilometers. The technique would enable a low-cost wireless extension of fiber between two points separated by difficult or expensive obstacles such as forests, bodies of water or train tracks.

Taara claims to have taken steps in establishing connections and adjusting environmental factors. Adjusting the mirror mechanism for aiming, among other things, would have helped. The project describes directing the beam of light with the thickness of a chopstick over a distance of 10 kilometers at a target of 5 centimeters. The system can automatically adjust the power of the laser according to conditions such as light rain. If the beam is interrupted, the system loses the connection and areas with a lot of fog, for example, are not suitable according to the project.

Alphabet has gained experience with laser communication as part of Project Loon. In that project, the company tested the use of balloons to provide internet access in remote areas. At the beginning of this year, Alphabet canceled that project because of the high costs.