Opens up broadband to hard-to-reach rural areas with 12Mbit/s over 6km
By Nick Flaherty www.flaherty.co.uk
iPlayer HD video at speeds of over 5.4Mbps across a 5.6km white space link from its research centre near Cambridge to a house in the rural village of Orwell. The early success of these trials demonstrates the potential importance of white space connections - which take advantage of unused TV spectrum – to deliver fast and cost-effective rural broadband to some 600,000 poorly served homes and business, as well as for new applications such as remote smart metering.
White space broadband has a practical range of up to 10km, versus just 4km for typical wired ADSL connections and the cost of deployment will be significantly less than fibre over long distances. While white space works much the same way as Wi-Fi, TV spectrum signals travel farther, are better at penetrating walls and require fewer access points.
“The TTP white space link is very much still work in progress but we expect to rapidly reach speeds of greater than 12Mbps over 6km using a single TV channel, compared to wired ADSL broadband that struggles to achieve 2Mbps with less than half the range,” says Richard Walker, Head of Wireless at Cambridge-based TTP . “Consumers will simply have to purchase a second TV aerial to go on the roof or in the attic, along with a white space router similar in size and price to that of an existing home router; while we believe charges will be equivalent to current ADSL costs.”
Working with technology partners such as Cambridge-based Neul, TTP is also looking to enhance performance by experimenting with high order modulation schemes and signal coding techniques to increase spectral efficiency and to ensure that white space connections can co-exist without interference to existing TV broadcasting. This also requires a sophisticated central database approach with heuristic learning and feedback mechanisms, in a similar way to internet search engines that learn from the information users request and ultimately select.
The drive for rural broadband has the support of the UK Government that recently allocated £360m to improve access across England and Scotland, while earlier this month OFCOM gave further support for white space by saying that it would allow multiple third-party providers to develop white space databases and make white space devices licence exempt. Ofcom expects that white space technology could be launched in the UK as early as 2013 and is already considering the future use of other white spaces such as those in the band currently used by FM radio services.
“White space developments are moving very fast and it is certainly a very exiting space to be in,” says Walker. “Using the white space available in TV spectrum is just the start; many of the same technologies can be adopted to harness other licensed spectrum allocations that are significantly under-utilised.”