BT: white space works - if you're not "hung up" on speed

28 Mar 2012

BT reveals the early results of its white space broadband trial in Scotland

BT's white space broadband trial is successfully delivering speeds of up to 8Mbits/sec, and could help extend coverage to outlying rural areas.

PC Pro visited Kilchattan Bay on the Scottish Isle of Bute, to see the results of a white space trial which started last April and runs until September.

While the trial is still ongoing, BT has successfully managed to provide broadband access to ten local farmers using so-called white space spectrum, the space between the frequencies used for TV.

The idea is that such radio signals can pick up where copper wires fail, extending the reach of broadband. The signal is picked up by an antenna on the customer's home - for one part of the trial, a modified TV aerial is being used - and run via a cable inside to a standard router.

"Customers don't really see a difference [at the point of use]", Brendan Dick, director of BT Scotland, said.

Hung up on speeds

Using a standard aerial, each channel can support up to 10Mbits/sec, but trials with a new piece of hardware offers up to 15Mbits/sec. The signal degrades over distance, but BT said it could offer up to 4Mbits/sec as far as 6km from the transmitter.

Everybody gets hung up about speed

The highest speed we achieved on location was 6.2Mbits/sec - and that was in sight of the mast. A point 6km from the transmitter had much slower speeds; we saw a top speed of 1.5Mbits/sec at the time, but BT claimed it has regularly achieved speeds of 3.5Mbits/sec.

The speeds are easily improved, however. Channels can be "bonded" together or one channel can be used for downloads and another for uploads. And as Chris Gibbs, BT Openreach's director of insight, innovation and futures, pointed out, speed isn't usually the problem, but contention, although that can be solved by adding extra channels.

"Everybody gets hung up about speed," Gibbs told PC Pro. "The real thing is can Robert McAlister [a local farmer taking part in the pilot] go online and sell his beasts on? Can his daughter sit there at the same time and watch BBC iPlayer? It might be you only need 8Mbits/sec shared over a few people."

McAlister farm

Indeed, white space broadband only works for small numbers of people. BT said it was targeted at areas needing to get "tens" of people online, not hundreds or thousands. That's not as dire as it sounds, as many exchanges in Scotland support fewer than 100 lines, BT noted.

The trial is also dependent on a 100Mbit/sec microwave backhaul to the mainland, but many rural areas may need submarine lines to connect to the core network. "If you don't have that, it doesn't matter what you have in your access network," said Gibbs.

BT said the trial showed white space was technically viable, but repeatedly stressed it will eventually come down to the bottom line. "I think the work we've done so far has been really encouraging," Gibbs said. "If we can get the technology integrated correctly and we can get the commercial performance correct, then I absolutely think we will see this kind of technology rolled out."

Satellite broadband

The speeds we saw aren't superfast - or any better than what satellite broadband currently offers. Gibbs claimed there's "more capacity in two cabinets than in a satellite", but willingly admits satellite broadband will be part of the larger picture when it comes to achieving the Government's goal of 100% coverage of 2Mbits/sec connections.

Indeed, Gibbs said UK broadband coverage would emerge as a "patchwork" - using different technologies where they best fit to solve rural not-spots.

"There’s no magic technology that’s going to come in and be the answer to your dreams," Gibbs said. "A lot of people claim it, but there isn’t.”

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