Alcatel-Lucent supercharges DSL with 30 percent speed boost

Stuart Corner
Thursday, 31 January 2008 15:54

Business IT - Technology

Another emerging technology that promises to significantly increase the throughput of DSL on twisted pair copper phone lines is dynamic spectrum management, and online newsletter ScreenPlays   this week quoted Marcus Weldon, CTO of Alcatel-Lucent’s Fixed Access Division, saying that sample DSM Level 3 chipsets for integration into Alcatel-Lucent products should be available in late 2008, and that some makers are beginning to build chipsets as external elements and in an evaluation stage  “For a real integrated commercial product, I would guess a year from then, taking into account all the use environments,” he said.

DSM involves the modem hardware (ADSL transceivers) automatically adjusting transmission settings in order to achieve the best signal. These adjustments could be to modulation technique, power levels or both. At its simplest DSM (level 1) enables these parameters to be adjusted for each copper pair so as to improve performance on that pair regardless of others. At the next level the parameters on every pair in a multipair cable would be individually adjusted to as to give an overall optimum performance on all pairs.

DSM Level 3 is akin to multiple input multiple output (MIMO) technology in wireless where the system makes use of multiple paths to deliver optimum data throughput. In DSM level 3 all pairs are managed individually so as to optimise total throughput on the multipair cable. A detailed technical explanation can be found in this Alcatel Lucent white paper, dated June 2005. At that time, according to the authors, DSM Level 3 was too complex for implementation on the available DSL digital chips. Progess has clearly been rapid.