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Last Updated: Sunday, 18 July, 2004, 12:24 GMT 13:24 UK
Wired broadband gets supercharged
By Chris Long
BBC ClickOnline

One of the technologies that brings us broadband, ADSL, is evolving into a faster beast called ADSL2+ which could revolutionise the way we use the net.

BT engineer at an exchange
Broadband is being carried via telephone exchanges
There can be little doubt that without broadband the internet would be a very slow place indeed.

But delivering broadband raises many issues for the service providers.

To get high-speed connections to urban areas means using a city's own phone infrastructure, an infrastructure that can be 100 years old.

Some of the copper expected to deliver high-speed data to our computers may have been around since Victorian times, and all of it is based on a technology dreamed up at the turn of the previous century.

"Nowadays we are trying to squeeze 25 megabits per second down a cable that was only designed to carry three kilohertz of traffic," explained Chris de Courcy-Bower of Lucent Technologies.

To prove the industry has a sense of humour it has long employed irony in naming its cabling - called Pots, or Plain Old Telephone System.

Copper technology

ADSL is the term a lot of us who use broadband will know. DSL is Digital Subscriber Line, and that refers to the connection between you and the exchange, and the "A" stands for Asymmetric, which means that you can download data faster than you can upload it.

Internet cables
New standard approved by the International Telecommunications Union in January 2003
Doubles maximum frequency for downstream data transmission from 1.1 MHz to 2.2 MHz.
Downstream data rates of up to 24 Mbps on phone lines
Provides optional mode that doubles the upstream bandwidth
"ADSL essentially solves the problem of infrastructure that exists throughout the world today," said Dylan Armbrust of Computer Active magazine.

"You have old copper lines beneath the streets of hundreds of cities and they've managed to squeeze every little bit of capability out of that copper technology.

"So it's really about making use of old technology to bring in the new technology."

In the next couple of months we will be seeing the next generation of ADSL called ADSL2+. It has been ratified by the men in suits and the manufacturers are gearing up.

"ADSL2+ will give you a much greater bandwidth to the home," said Sarah Kemp of Nokia.

"For instance, if you live within 2km of a central exchange you can have up to 24 megabits to your home.

"Alternatively, you can run ADSL in 'Reach Extended' mode and have up to 200 kilobits per second up to 7km from the local exchange. So you have it both ways. Either lots of capacity close to, or less but further out, compared with ADSL."

Reaching more people

Nonetheless, ADSL over ageing copper is not necessarily the infrastructure you would want to start with.

"If they can possibly avoid it, the companies don't really want to spend money on upgrading their infrastructure because something like fibre optic costs an awful lot of money to put down," said Mr Armbrust.

Family at home using broadband
More and more people are getting fast internet connections
"You've got to wire every street, every county, every nation if you decide to go that route. And it's a long-term commitment as well.

"There are great financial resource issues involved, there are great infrastructure resource issues involved, so the longer they can delay that the better off they are and the better off their bottom line is, in the short term."

For internet providers, it is all about trying to reach as many people as possible, in order to maximise revenue.

"In Europe you still have large urban areas where you have people concentrated within about 4 or 5km of a local exchange, so an operator can tackle a lot of people with one central point," said Ms Kemp.

"They can then put a remote hub out in an area or village with, say, several thousand people, put electronics closer to them and then offer DSL that way.

"A lot of those countrified areas have high users of technology, so it makes a good business case.

"This doesn't work quite the same in places like Africa, where the services that are needed may be different, and also the population is so much more spread out," she said.

The good news is that some of us are getting faster broadband, and the bad news is that this does not affect the people who need it most - the ones that live outside cities.

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