BT to stretch ADSL wires

BT hopes to broaden its ADSL coverage without upgrading more exchanges or replacing copper phone lines

Dinah Greek, IT Week, IT Week 28 Feb 2003

BT Wholesale plans to extend the reach of Asymmetric Digital Subscriber Line (ADSL) broadband to connect more customers.

BT is reviewing the standards governing ADSL's reach in an effort to stretch the service beyond the current 5.5km radius around exchanges. It hopes to deliver a 512kbit/s service to a wider audience without having to upgrade either the exchange or the copper phone lines.

DSL signals can be sent over much longer distances than 5.5km, but this has traditionally been at the expense of data speed and reliability.

If BT can increase the distance and a viable service can be established, the company estimates the potential number of people able to access broadband will rise from 93 percent to 97 percent of the UK population. With contention ratios of 20:1 for business services, BT hopes to roll out trials across the country by the end of the month.

About six percent of households in the UK are connected to ADSL exchanges, but cannot get broadband services because the reach of ADSL has been limited by a maximum acceptable noise level on the line of 55dB, which occurs at around 5.5km.

Beyond this distance, signal quality has been too poor to offer to customers. But BT has been re-examining the standards and now believes that noise levels can be pushed to 60dB without too much degradation of service, which would substantially extend the reach.

BT runs the risk of degrading the signal to the point where the connection is repeatedly dropped, and the carrier's tests will focus on gauging how much data can be transmitted over what distance while maintaining a reliable signal.

BT is already testing the service with a dozen users. A BT spokesman said the company will roll out wider trials by the end of March and also hopes to interest a range of ISPs in the project. "We are looking at the possibility of extending the reach but as it is early days the numbers on the current trial are very small. We are not upgrading exchanges as all we are doing is pushing out the standard ADSL acceptable noise levels from 55dB to 60dB," he added.

Michael Philpott of analyst firm Ovum welcomed the initiative. "BT has been under a lot of pressure to push ADSL out to more rural areas and everyone expected that it would be a lesser service or more expensive. Increasing the coverage while allowing customers to get the same service is a very positive move."

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