BT Expands Trial of White Space Wireless Broadband Technology to Cornwall UK

BT has confirmed that it plans to expand upon last year’s Cambridge and Isle of Bute based trials (here) of “White Space” (IEEE 802.22) wireless broadband technology, which makes use of the radio spectrum that exists between Digital Terrestrial TV (DTTV) channels to deliver internet access services, by launching a new commercial scale test in Cornwall to replace its current 4G (Mobile Broadband) trial with Everything Everywhere (Orange UK and T-Mobile).

The 4G trial, which was recently extended (here) but is due to end before July 2012, runs in the 800MHz spectrum band that will be auctioned off by the telecoms regulator (Ofcom) towards the end of this year. By comparison “White Space” tech picks out small chunks from spectrum that already exists for DTTV services between the lower 470MHz to 790MHz frequencies (travels further and more easily through walls).

Digital TV services typically leave a small gap (the white space) between channels to limit the potential for interference and this is what white space technology aims to use. The official specification suggests that download speeds of up to 22Mbps per channel could be possible (UK trials have reached around 16Mbps), which would be shared (contended) with other users.

BT’s Head of Strategy, Sean Williams, confirmed the development yesterday (FT) and hinted at plans for a national UK service. However the service is complicated to deliver and Ofcom is still busy trying to pin down the many varied regulatory issues.

Ofcom’s CEO, Ed Richards, told yesterdays Dynamic Spectrum Access Forum (Brussels):

“I want to suggest to you today that we now need a common and co-ordinated approach to this increasingly vital area, starting with TV white space devices but ultimately looking to establish dynamic spectrum access much more widely.

By enabling TV white space devices in the UK we aim to show the potential of the technology. To fully realise the benefits of dynamic spectrum access, however, we need collective European commitment to support it further.

The model we are pushing in the UK is for the regulator to control the white space device transmit power. If harmful interference occurs we can turn down the power.”

One key problem is that White Space connectivity hardware (i.e. routers) would first need to consult a DTTV frequency database hosted online before they could work. Digital TV channels often swap frequencies and failing to use the correct ones could result in interference, thus it’s necessary to keep an up-to-date and locally aware database. Meanwhile some continue to have concerns about the viability of this and whether or not interference will still be an issue.

In theory White Space technology could help to reach isolated rural villages with faster connectivity (its practical range goes up to around 10km) and for a potentially lower cost than either WiFi or Mobile Broadband based alternatives. But before that Ofcom must consult on a Draft Statutory Instrument for making white space devices licence exempt, although in theory the first commercial UK services could arrive during 2013.