Facebook and Nokia speed up undersea fiber through math

It's up to 2.5 times faster without having to replace cables.

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Undersea fiber optic lines are crucial to making the internet hum, but upgrading their capacity is no mean feat when you may have to replace thousands of miles of cables. Facebook and Nokia don't think that's necessary, though. They've successfully tested a technique that can boost the capacity of a fiber line by up to 2.5 times its stated capacity. Their approach revolves around Nokia's probabilistic constellation shaping, which relies on 'shaped' modulation formats (i.e. a lot of clever math) to push the capacity to near the physical peak of a given connection. In tests on a 3,400-mile line between New York and Ireland, the two companies managed to wring out 200Gbps on commercial-grade wavelengths, and an even speedier 250Gbps on an experimental link.

The technology has even more headroom. Based on the efficiency of the line, Facebook and Nokia believe they can ramp it up to 32Tbps per fiber in the long run.

It's likely going to be a while before you see these kinds of upgrades arrive in earnest, although the test runs show that it can hold up in real conditions. Whenever it does, though, the practical implications are far-reaching. The upgrade could help these fiber line operators keep up with ever-increasing internet demands without having to rip up or add to their existing lines. It could also make undersea fiber more practical by lowering the cost of bandwidth -- you could see lines that weren't viable before.