Using VDSL2 Vectoring To Shut Out The Noise

While operators with cable and fiber plant may disparage telcos regarding their older copper infrastructure, the fact remains that DSL is the dominant access technology worldwide. According to The Broadband and IPTV Growth Report presented at the Broadband World Forum in Paris by industry analyst Point Topic, "DSL alone, as distinct from the part copper plays in many hybrid deployments, was responsible for 52.65 percent of the net broadband lines added in the twelve months ending June 2011."

Alcatel-Lucent has enhanced its broadband portfolio with the commercial availability of very-high-speed digital subscriber line (VDSL) 2 vectoring technology to boost the data speeds and capacity of existing copper access networks, permitting broadband speeds as fast as 100 Mbps.

VDSL technologies boost bit rates and VDSL2 bonding combines two or more lines to increase bitrates further or deliver the same bitrate over longer distances.

According to Alcatel-Lucent, with more than 1.25 billion of the world’s households currently connected to copper lines, such next-generation DSL technologies as VDSL2 and vectoring provide effective ways to provide more bandwidth to more subscribers using existing copper resources.

Belgium’s Belgacom is Alcatel-Lucent’s first customer for its VDSL2 vectoring technology. Belgacom believes it can boost performance over its national triple-play network to provide guaranteed speeds as fast as 50 Mbps by 2014.

Stefaan Vanhastel, who leads the marketing activities for Alcatel-Lucent’s Fixed Access portfolio, says a lot of telcos already are using VDSL2 technology, typically in conjunction with some kind of deep-fiber deployment.

"The biggest problem with DSL is noise," says Vanhastel. "VDSL2 vectoring is more or less noise cancellation to DSL lines." He adds copper lines typically are deployed in bundles packed closely together, and that they are prone to cross-talk interference. In the ideal conditions of a laboratory, VDSL technology can deliver data speeds of 100 Mbps at 1,200 feet but, in real-world conditions with cross-talk, speeds drop to between 30 Mbps and 60 Mbps. The vectoring noise cancellation works by measuring the noise in the signal and then generating the inverse signal.

"Every line in the field behaves as if it were in the lab, getting near optimal performance in the field," explains Vanhastel.

Rob Gallagher, principal analyst and head of broadband & TV research at Informa Telecoms & Media, said in a statement, “Alcatel-Lucent’s plan to make VDSL2 vectoring commercially available is very timely. Service providers and governments have stated their intent to boost broadband speeds to consumers and businesses alike, but the challenges associated with comprehensive fiber-to-the-home deployments have been a major obstacle.”

-Linda Hardesty