As the telecommunications industry converges in Paris for the Broadband World Forum, it would be natural to look for evidence of further advances in FTTH rollouts and technologies. But even as FTTH technologies gain market share, shipments of DSL equipment continue to be strong.

 

In fact, after a decline in 2007–09, shipments are hitting new highs. We forecast that there will still be almost 400 million DSL subscribers five years from now, including many on hybrid copper-fiber networks, and additional in-building VDSL2 in FTTB networks.

 

Recently, there were a number of VDSL2-vectoring-related announcements by equipment and software vendors. But Alcatel-Lucent’s commercial launch of its VDSL2 vectoring solution is a first. Alcatel-Lucent claims the solution has the capability to support 100Mbps at 400 meters.

 

VDSL2 shipments in particular, while still a small proportion of shipments, have been growing steadily and in 2Q11 crossed the five million port mark. The result is due to a number of ongoing FTTN and FTTC/Cabinet type of deployments where part of the loop between the central office and the home is replaced by fiber and then ADSL is upgraded to VDSL2 to take advantage of the higher potential throughput on shorter loops.

 

But cross-talk between one copper pair and another, as well as other sources of noise, reduce that theoretical throughput considerably.

 

Standardized by the ITU in April 2010, vectoring is a type of noise-cancellation technology that helps regain some of the VDSL2 line’s lost throughput. DSL line bonding, vectoring, and “Phantom DSL” are the three ways that can potentially boost copper network speeds, of which bonding is already being implemented. AT&T is bonding its VDSL2 lines in the US for extended reach. We don’t expect Phantom DSL to be commercially available before the end of the 2012–13 timeframe. These options will help service providers to utilize existing copper access infrastructure, with partial fiber deployment, but before taking fiber all the way to the home.