Alcatel-Lucent Technology Could Deliver Broadband Over Copper Cables
A trial has been carried out of a way of delivering high broadband speeds over copper wires for the so-called "last mile" connection between homes and the local network cabinet in the streets.
Alcatel-Lucent and Telekom Austria carried out the trials based on adaptation of Bell Labs vectoring techniques -- already in widespread commercial deployment in VDSL2 networks -- to use a wide frequency band to achieve very high speeds on copper lines over very short distances.
The technology, which the company is calling "G.fast" is intended for typical applications of 500Mbps speeds at 100 meters or less.
In any fiber-to-the-home project, a substantial part of the cost-per-subscriber is in the last few meters between the nearest network cabinet and the home. These costs might be avoidable by using G.fast over the existing copper telephone line, rather than having to dig up roads or private property to install new fiber.
Bell Labs vectoring technology addresses one of the challenges related to the deployment of G.fast. In many real-world applications, such as fiber-to-the-building, the copper lines serving neighboring homes are packed closely together: this results in crosstalk interference between lines, which significantly reduces the potential speed of data transmission. G.fast vectoring removes this crosstalk, stabilizes the transmission quality and enables the technology to perform to its full potential.
The trial, conducted with Telekom Austria first tested G.fast over a single, good quality cable, achieving a maximum speed of 1.1 Gbps over 70 meters and 800 Mbps over 100 meters.
On older unshielded cables, typical of most in-building cabling in Austria, the trial achieved speeds of 500 Mbps over 100 meters on a single line. However, when a second line was introduced, creating crosstalk between the two, the G.fast speed fell to only 60 Mbps.
Vectoring was then enabled, removing the crosstalk and bringing the speed back up to 500 Mbps over 100m.
G.fast, which is not yet standardized, won't be commercially available for several years. However, Alcatel-Lucent said that it is a natural evolution of VDSL2 that, with the help of vectoring technology, could allow service providers to more quickly and cost-effectively provide subscribers with broadband speeds from several hundreds of Mbps up to more than 1 Gbps over short distances.