BT stretches ADSL to reach a million more

An experiment in Milton Keynes will expand access to ADSL by increasing the effective range of the service from 6 kilometres to 10 kilometres

BT has announced details of a broadband trial taking place in Milton Keynes this summer that could eventually make high-speed Internet access available to another million people across Britain.

The telco believes that it can now offer its ADSL service over a longer distance than previously thought. At present, a home or business whose connection to the local exchange is more than 6 kilometres long generally can't get ADSL. However, BT is now looking to push that upper limit to as much as 10 kilometres.

"By extending reach, we will bring service to many of those in the frustrating situation where their exchange is upgraded for broadband, their neighbours down the road have broadband, but they can't get it," said Alison Ritchie, BT's chief broadband officer.

ADSL works only over a limited distance because its signal loss is directly proportional to the length of the connection. The current signal loss limit is 60 decibels (dB) and engineers in BT's testing labs at Adastral Park now believe that that limit can be increased in some cases. Currently, 4 percent of the overall population are connected to an ADSL-enabled exchange but live too far away to get the service. This equates to about one million homes and businesses.

Up to 1,000 people will be involved in the trial, which should start on 1 June. Milton Keynes has been chosen because 18 percent of people in the city can't get ADSL.

This is an unintended consequence of the Milton Keynes grid system, in which intersecting dual carriageways criss-cross the city. Telephone networks often route around them and some residents find their phone line goes around three sides of a square -- pushing its length beyond 6km.

BT plans to launch services with longer reach later this year if the Milton Keynes trial is successful, but it may decide not to establish an official new maximum distance over which it will guarantee to offer ADSL.

"The outcome of the trial could be that we set a new limit, of it could be that we just encourage people to apply for broadband in the knowledge that some will be able to get it and some won't," said a BT Wholesale spokesman.

BT's researchers have found that the condition of a home or business's internal wiring becomes a more important factor for those over the 6km limit. Upgrading this wiring could help to make ADSL work but the complication is that BT doesn't own this wiring.

One solution could be to install a wireless-access point or router at the point where the copper line first enters the premises.