Bell Labs bridges a gigabit over a copper gap

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The case for copper. Source: Alcatel-Lucent.

AT&T and Verizon should think twice about running away from older copper networks. Bell Labs has prototype technology that can already move half a gigabit through legacy wiring. Testing by parent company Alcatel-Lucent and Telekom Austria succeeded in pushing more half a gigabit over multiple legacy copper POTS pairs, using elements of the emerging G.fast standard and mixing in advanced vectoring technology – dubbed Vectoring 2.0 – developed by Bell Labs.

G.fast is an International Telecommunications Union standards initiative that’s intended to eventually develop technology that will allow 1 Gbps data speeds over copper telephone wiring at distances up to 250 meters.

There’s no free lunch. Although Bell Labs managed to hit 1.1 Gbps over 70 meters of a single, good quality copper pair and 800 Mbps at 100 meters with current G.fast gear, speeds dropped dramatically when older plant was tested. By itself, a legacy unshielded pair was able to carry 500 Mbps for 100 meters, but the crosstalk generated by lighting up a second pair in the bundle dropped throughput to 60 Mbps, putting it back into current VDSL2 territory.

Adding the Vectoring 2.0 technique cured the crosstalk problem. It expands the bandwidth of vectoring technology by more than a factor of ten, and brought throughput back up to 500 Mbps.

The objective is to create “the fixed networks equivalent of wireless small cells”. G.fast performance drops quickly as copper distances stretch out toward 200 meters or more. But if the promise holds and fiber is installed far enough into the network – think fiber to the curb or basement – homes might soon see gigabit speeds at significantly lower costs.

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