Speeds on copper lines used for DSL broadband links could reach 50Mbits/sec if operators' modems were shifted from exchanges to street cabinets, says a new report from regulator Ofcom.

The top speed would be available to anyone living with 2km of a cabinet, which amounts to virtually all homes. Currently modems are sited in local exchanges, making top data rates available to only 18 per cent of homes.

This has led to complaints from users that they are not getting anything like advertised data rates.

Ofcom stresses that the figures are theoretical but it says they set an upper limit on what can be expected from copper and show that its full potential has yet to be reached.

It would involve fibre being run to street cabinets but this is far cheaper than running fibre to the home.

Ofcom points out: "Data rates experienced by end users depend not only on the distance between the customer premises and the exchange but also on home wiring and interference at the exchange, cabinet and in the home."

The observations on line speed come in an overview of broadband in the report, called Tomorrow's Wireless World.

The report confirms what Ofcom officials have privately told PCW – that they expect congestion in the 2.4GHz band to drive users to the less crowded 5GHz band supported by Wifi types 11a and 11n.

It reveals that Ofcom is to launch a study of congestion levels but warns that it could be tricky to do. "Congestion may only occur in a small area, such as at the middle of a shopping centre but not at the periphery, or it may occur only at certain peak times of the day."

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