100Mbps out of of copper?

A technology called bonding that takes advantage of the fact that most people have not one but two copper phone lines in a single cable running into their homes could be used to deliver faster broadband.

This could be of particular use to rural homes, where the performance of copper-based DSL technology is often left wanting.

Telecom technology partner Alcatel-Lucent demonstrated that it could deliver broadband speeds of 70 megabits per second (Mbps) over copper by using both lines – two twisted pairs – to support a single internet session.

The company showed four high-definition televisions at the offices of Telecom's network arm, Chorus, playing programmes that were streamed over two standard 0.4-millimetre-wide, 630 metre-long lines. These were connected to VDSL2 internet access equipment at its central Wellington exchange.

That is a "typical real-world scenario", because 630m is the average length of a copper line, says Alcatel-Lucent New Zealand chief technology officer Martin Sharrock.

In the past, customers often needed two phone lines to support a phone and fax, or used the second line for dial-up internet.

Mr Sharrock says bonded internet connections are not yet available anywhere, but are "right on the edge" of becoming commercial.

Customers would need a special broadband modem, capable of splitting and integrating transmissions over two lines.

"The future is fibre," he says, but techniques to squeeze more out of copper lines would help the quarter of households that won't benefit from the Government's $1.5 billion ultrafast broadband initiative.

Download speeds of 30Mbps were possible over longer 1.5-kilometre copper lines, while even households 4km away from a cabinet or exchange could expect speeds of 6Mbps.

A connection speed of about 7Mbps is required to support a single high-definition channel.

"We have to make the most of the asset until the fibre comes, or for those few people who may not be in the luxurious situation of receiving fibre to the home," he says.

"We feel it is possible to achieve 100Mbps with one bonded system."

Higher speeds could be obtained by businesses by bonding several copper phone lines.

InternetNZ spokesman Richard Wood notes that as Chorus charges by the line, bonded connections would cost its telco customers twice as much, unless it introduced a more sophisticated pricing regime.

Chorus product manager Chris Dyhrberg does not rule that out. "Who knows? At the moment it is hard to find a way of encouraging people to buy a second line."

Chorus' copper lines are about 40 per cent utilised, he says. "There would have to be industry discussion and agreement about how it would use a technology like this, but I don't see that as a big challenge."