Alcatel-Lucent Stretches DSL to 300 Mbps, Easing Transition to Fiber

  • DSL
PARIS – By combining a 19th-century analog technology with today's most advanced technologies, Alcatel-Lucent engineers have demonstrated a new way to boost the capacity of DSL. With the new combination of technologies, Alcatel-Lucent's Bell Labs demonstrated transmission speeds of 300 Mbps over 400 meters and 100 Mbps over 1 km.

Product marketing manager Stefaan Vanhastel says, "Fiber to the home is the long-term strategy, but even if operators are going full speed ahead, it will take a few years. ... If 50 percent of your customers have FTTH, what do you do with the other 50 percent? Will you tell them they can't have high-definition TV and other new services? That's commercial suicide. So this is the ideal transition for the short and medium term, until you fill the gap."

The 19th-century technology resurrected by Bell Labs is called Phantom Mode. It involves the creation of a virtual or “phantom” channel that supplements the two physical wires that are the standard configuration for copper transmission lines. (See Alcatel-Lucent's wonderful graphics below for a more detailed explanation.) Phantom Mode was invented in 1882 and was used for many years to deliver three phone lines over two copper loops. It can be implemented with transformers and other analog equipment and does not require chipsets.

Bell Labs’ innovation, and the source of DSL Phantom Mode’s dramatic increase in transmission capacity, lies in its application of phantom mode technology in combination with two other techniques: vectoring, which eliminates interference or “crosstalk” between copper wires, and bonding, which makes it possible to aggregate individual lines.

This combination of technologies, which is likely to be commercially available by 2012, will help operators that have built out fiber to within 1 km of the customer premises, and that have two copper loops running from the DSLAM to each customer premises. With this infrastructure - which is common in many of today's telephone networks - operators will be able to deliver at least 100 Mbps downstream, using the industry-standard VDSL2 protocol and with relatively minor upgrades to their equipment. Upstream bandwidth will also be significantly improved, although Alcatel-Lucent's announcement did not give specific rates. That means operators will be able to provide most of today's advanced services over fiber-to-the-curb and fiber-to-the-building networks, and even over many fiber-to-the-node networks.


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