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DSL/vectoring/G.fast

Telekom Austria Tests G.fast

PARIS -- Alcatel-Lucent (Euronext Paris and NYSE: ALU) and A1, the Austrian subsidiary of Telekom Austria Group, have conducted the world's first trial of an innovation from Alcatel-Lucent's Bell Labs that can upgrade existing copper telecommunications networks into ultra-fast broadband access systems capable of delivering video, data and information at speeds of more than 1 gigabit per second (Gbps).

With Alcatel-Lucent repositioning itself as a specialist in IP Networking and Ultra-broadband access, the company has adapted Bell Labs vectoring techniques - already in widespread commercial deployment in VDSL2 networks - to work with a new transmission technology called G.fast, which use a wide frequency band to achieve very high speeds on copper lines over very short distances.

G.fast is intended for typical applications of 500 megabits per second (Mbps) speeds at 100 meters or less. In recent demonstrations and under laboratory conditions, Alcatel-Lucent achieved 1.3 Gbps over 70 meters, making G.fast a promising option for service providers to complement their fiber deployments.

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 can be avoided 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.

Key Facts
  • The trial, conducted with A1 and using a Bell Labs prototype, 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. This is a huge improvement over widely deployed DSL networks, which typically offer speeds of 5-30 Mbps, or VDSL2 vectoring networks supporting up to 100 Mbps. Fiber-to-the-home services typically range from 100 Mbps to 1 Gbps.
  • G.fast, which is not yet standardized, won't be commercially available for several years. However, 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.

    Alcatel-Lucent
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