the broadband revolution will not be televised

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Mobile operators have been looking lasciviously at the spectrum freed up by the switchover from analogue TV to digital. They want the extra spectrum for 4G LTE services to satiate our appetite for mobile broadband.

But there is a new broadband kid on the block that also wants a share of the digital dividend (the name for the analogue switchover), and it's happy to settle in between the TV broadcaster and mobile operators.
 
TV white space technology is an innovative way of interlacing wireless data communications alongside TV broadcast. Proposed by the IEEE and  the Wireless Innovation Alliance, it can deliver very high data rates over extremely long distances with low latency and at low cost. One company claims it can deliver 8Mbps at ranges of up to 5.5km using a single TV channel's worth of spectrum. The range can be extended much further with a comparable trade-off in throughput.
 
There have been a number of proposed applications for this unlicensed technology including smart grids, home automation and "Super Wi-Fi".  

white space tech can use unlicensed spectrum 

In the US, the FCC now permits the use of white space devices (WSDs) without a licence. In the UK, Ofcom recently also announced it intends to allow white space devices to operate without a licence, with regulation set to appear next year.

Practically, the technology faced resistance from broadcasters concerned with potential TV signal interference and with TV equipment such as microphones. This prompted development of management systems to mitigate it. Such solutions direct devices to clear white space channels, so-called "spectrum harvesting". 

The first US-approved solution comes from Spectrum Bridge, a company now collaborating with others (including InterDigital) to develop Dynamic Spectrum Management tools. Telcordia is also working to develop its own system, suggesting similar harvesting tools from other third-party developers as yet unknown will emerge in future.
 
Seen as a model for future smart city development, this relatively unpopulated bandwidth could also provide an internet connection for future M2M (Machine-to-machine) devices . White space devices could manage traffic congestion, energy efficiency and environmental sensing - or any application where there is a need for long-range communications but does not depend on real time, guaranteed quality of service. 

Super Wi-Fi goes live in North Carolina

The first white space-based smart city switched on in Wilmington, North Carolina back in January. There, Spectrum Bridge offers a cloud-based spectrum management platform that uses those TV frequencies left behind by the digital TV transition. No surprise Wilmington is the first US city to have already made the transition to digital broadcasting. Now the city is using the tech to enable public Internet access and broadband-based video security systems, under  the monikor of Super Wi-Fi.

With the digital switchover in the UK set to reach its finale later this year (PDF), a company called Neul recently delivered 16 megabits per second over a range of 10 kilometers in UK tests. "That puts white spaces on a par with 4G," notes Akshay Sharma, Gartner’s research director. 

White space broadband is expected to evolve as complementary to existing technologies, though could play a part in bringing remote rural areas online and in connecting those new generations of M2M devices in future, Sharma predicts.
 
But don't expect too much too soon. A recent Cambridge Consultants report claims we'll see enterprise White Space devices begin to appear this year, with a range of consumer-focused solutions entering the market in five years. The challenge will be in establishing common standards to enable manufacturers to bring their solutions to market.
 
"A priority now should be establishing standards to allow for common platforms, economies of scale and large scale uptake. Without standards, White Space could be a footnote, but effectively marshalled White Space has the potential to deliver even greater innovation and new services that we have seen in previously unlicensed spectrum such as Wi-Fi and Bluetooth," said Fraser Edwards, Head of Radio Frequency Systems at Cambridge Consultants.
Stewart Baines

I've been writing about technology for nearly 20 years, including editing industry magazines Connect and Communications International. In 2002 I co-founded Futurity Media with Anthony Plewes. My focus in Futurity Media is in emerging technologies, social media and future gazing. As a graduate of philosophy & science, I have studied futurology & foresight to the post-grad level.