Telstra foreshadows 100Mbps DSL

By Stuart Corner
Friday, 02 November 2007 05:54

Technology

Telstra has raised the prospect of being able to deliver up to 100Mbps using DSL technologies over its existing copper pair network using a technique known as dynamic spectrum management (DSM), which is just becoming commercially available.

However to achieve its full potential DSM would require every copper pair in a multipair cable to be operated and managed by one DSL operator. The way DSL in Australia operates today each ISP either has total dedicated access to a copper pair (the unbundled local loop or 'naked DSL') or else connects that copper pair to its own DSLAM while Telstra, or another operator uses the lower end of its spectrum to deliver a standard telephone service.

Telstra's chief technology officer, Hugh Bradlow, told Telstra's investor briefing on 1 November that "In order to be able to support increasing speed demand, we're working on a range of technology platforms that will allow us to scale into that future world...We've got copper solutions, cable solutions and fibre solutions. In the copper environment, we have ADSL2+ covering 57 percent of Australia's 8.5 million homes, but we're already working on the next two generations of copper based technology, VDSL2 and dynamic spectrum management, both of which will increase the speeds by doubling, so that the copper technology has the potential to get up to 100Mbps."

DSM, according to Wikipedia. "is a technique being researched to improve Digital Subscriber Line (DSL) performance over ordinary copper phone lines by reducing or eliminating crosstalk between DSL phone lines that are close together. The technique 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) it enable 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.