After a few years of testing, the UK has approved the national use of white spaces for high-speed, long-range mobile data networks. In this context, the term "white space" refers to gaps in the UHF radio spectrum between 470MHz and 790MHz that were previously occupied by analog broadcast TV but have since been vacated by the switch-over to digital terrestrial television (DTT). Low-frequency wireless networks are highly desirable because their signals can propagate over much larger distances and pass through obstacles (like brick houses) without attenuating beyond repair. White space networking could be a key technology to the eventual deployment of the utopian but vaporous promise of the "Internet of Things."

Over the last few years, most of Europe, the United States, and a smattering of other countries around the world have finally turned off most of their analog TV stations. These analog stations occupied huge swaths of the VHF and UHF spectrum blocks, with only a few channels reserved for other uses, such as FM radio and military communications. Because digital television signals are compressed and multiplexed, they can be squeezed into just a handful of those original analog broadcast channels, leaving a large amount of free space between 470MHz and 790MHz. Now, countries are moving quickly to repurpose these white spaces and alleviate the spectrum crunch caused by the rapid growth in wireless networking and mobile computing.

The main problem with using these TV white spaces is that they're not completely empty. With licensed spectrum, you are (mostly) guaranteed not to get any interference in your block of frequencies no matter where you are; with white spaces, a channel might be unoccupied in one town, but used in another. As a result, countries like the US and UK are opening white spaces up for unlicensed use, but often with the rather sizable caveat that devices must be imbued with enough smarts that they don't transmit on frequencies that are being used by other services.

For example, in the UK, devices must be aware of their own physical location (via GPS or similar), and they must be able to access a dynamically updated white spaces spectrum database to see which channels are currently available.

In the UK, Ofcom—essentially the British equivalent of the FCC—says the first wide-scale white space networks could be deployed as soon as the end of 2015. We suspect it might be a bit longer than that, as consumer devices and networking equipment that use white space frequencies are still in early stages of development. The FCC approved unlicensed use of white spaces in the US way back in 2008, but there have only been a handful of small, low-range deployments.

As demand for omnipresent mobile data access continues to soar, the recently vacated white space spectrum is one of the largest and most exciting untapped resources. When it comes to long-range wireless networks, lower frequencies are generally preferred because they can travel farther and penetrate obstacles much more effectively than higher frequencies. As far as mobile carriers are concerned, this means you can cover a larger area with fewer base stations. For consumers, low-frequency networks should mean better connectivity in rural areas and indoors. And then there's that whole "Internet of Things" thing—white space networking could be a major factor in connecting together all the different devices that make up smart homes and smart cars, since those are places where network ubiquity and reliability trump raw speed.