BT aims to stretch ADSL reach

BT Wholesale is hoping to stretch the reach of Asymmetric Digital Subscriber Line (ADSL) to homes currently situated too far from local exchanges to receive broadband.

The telco claimed that it will be possible to provide a viable 512Kbps service without having to upgrade exchanges or copper phone lines.

This tackles head on a problem that affects around six per cent of households in the UK.

Although they are situated near upgraded local exchanges, they are unable to get broadband services because the reach of ADSL has been limited to a maximum level of 'noise' on the line of 55dB. This equates to around 5.5km in distance.

Beyond this the technical limitations of ADSL mean that the service quality has been too poor to offer to customers.

But BT has been examining the standards governing ADSL reach and now believes that noise levels can be pushed to 60dB without too much degradation of the service.

If it is able to increase the distance and establish a viable service, BT estimates that the number of people able to access broadband will rise from 93 to 97 per cent.

Limited trials have already begun using around a dozen households.

According to a BT spokesman, the company plans to start more widespread trials by the end of March and hopes at the same time to interest a range of internet service providers.

"We are looking at the possibility of extending the existing reach but, as it is early days, the numbers on the current trial are very small," he said.

"We are not upgrading these unbundled exchanges as all we are doing is pushing out the standard ADSL acceptable noise levels from 55dB to 60dB.

"It is difficult to say in distance how much further this will extend the reach from certain exchanges as it can vary.

"It will depend on local circumstances and the length of the copper wire involved rather than distance.

"The current trials will be looking at potential service problems caused by more noise on the line, such as if customers keep getting chucked off [the service].

"It is no use trying to offer a service if it is always getting cut off."

These trials should not be confused with those of lower bandwidth broadband of 128Kbps that BT is looking at testing in late March or April.

Trials of this midband range, as BT calls it, will provide a lower bandwidth using different technologies to ADSL.

Meanwhile, as part of BT's ongoing scheme to convert local exchanges, another 20 around the country will be converted during May.

These include Tavistock in Devon, Newton in Mid Glamorgan, Irvine Old Town in Strathclyde and Thirsk in North Yorkshire.