It might sound like the title of a sci-fi movie, but ‘white space’ is an area of untapped digital business potential in the UK and worldwide.

Unused areas of wireless spectrum could play a big part in meeting the boom in demand for data services, as long as there is an efficient way for the service providers to share the space.

Communications regulator Ofcom has its eye on the possibilities and is opening the unused parts of the digital TV spectrum – between 470-790 MHz – for a collection of trials. It aims to make it all more widely available, on a non-licensed basis, for new wireless applications from some time next year.

White space can exist in any areas of spectrum that are between airwaves, and the trials’ main focus is on minimising the risk of interference in the TV signals from existing spectrum users. They include tests on devices, the databases that identify what spectrum is available, and the processes to prevent interference.

In addition to supporting technology tests, Ofcom is developing policy to establish the rules for using the space, which could go to a public consultation before going into operation.

There is plenty of diversity in the nine trials, which are run by an assortment of private sector and research bodies and includes a couple of big names such as Microsoft and Google. Two trials are focused on digital signage, two on internet services on seagoing vessels, and others on external wi-fi and webcam backhaul, research and development, community sensor networks for flood detection, and live video feeds.

The latter nudges into the animal world with streams of meerkats, otters and giant tortoises from London Zoo.

Technology challenges

The project run by the Centre for White Space Communications at University of Strathclyde, which is partnering with Microsoft, provides an example of the technology challenges. It is focused on outdoor wi-fi and webcam backhaul, with white space offering a longer range than existing wi-fi and Bluetooth facilities.

Dr David Crawford, manager of the centre, says it wants to ensure that the links from a base station to multiple client devices – known as point to multipoint – will work effectively. The devices cannot all talk to base station simultaneously and their transmissions have to be scheduled, which is a significant challenge for webcams as they require a high data rate and provide a time critical service. It requires optimal scheduling of their MAC (Media Access Control) algorithms, and there is an extra challenge in ensuring they do not interfere with other white space devices.

He says the university campus has a workable solution in place and that some companies have developed products, but it will not be possible to use them on a wide scale until the regulations are in place.

Crawford points to possible opportunities directly related to the work with webcams in the security and entertainment industries, and says the provision of public internet access could be an important local government service that would be cheaper than now because it would not involve licensing. But “it’s not completely clear known what the business models will be, a bit like wi-fi 15 years ago”.

He adds: “We are using webcams and wi-fi  access as applications that demonstrate the uses white space can be put to. There are applications out there, some maybe suitable for a city centre, some for rural or semi-rural areas.”

Broad possibilities

It is difficult to identify the commercial possibilities with much precision, according to Dr William Webb, a former director of technology resources at Ofcom who is now chief executive officer of Weightless, a special interest group working on open standards for wide area network technology. But he says there are three broad categories that show some promise.

The first is rural broadband, helping to fill gaps in the networks where there is little prospect of fibre cable being installed. The second is the internet of things, where TV white space could be used to build wireless networks for machine to machine connectivity and support the development of smart cities.

“TV white space brings three advantages for this,” he says. “One is that it’s in a good frequency band for long range signal propagation.

You can make devices with very low power transmitters which will have a battery life of 10 years or more.

“Another is that there is quite a lot of spectrum available, which gives plenty of room to handle large numbers of devices. And it is free, non-licensed, which is great when you are looking for new areas and wondering what the return on investment will be.”

Webb says this could be “an absolutely huge area”, citing predictions that there will be 50bn connected devices in the world by 2020.

But he provides a note a caution with the point that work on the Weightless standard, in which he is involved, has been moved away from the TV spectrum.

The third category is sometimes called ‘super wi-fi’, using bands for a variant of wi-fi able to go further because of low frequencies. Webb says this has prompted the interest of Microsoft and Google, and that there could be opportunities in the provision of relevant services and applications, and in making the wi-fi chips to support the devices.

International inaction

But he also points a major barrier to realising the commercial potential. One derives from the fact that at the moment the UK is going it alone in Europe in opening up white space; the US has done so and Singapore is making moves. Regulators in other countries have been slow to address the issue as they are not yet seeing a big demand to use the white space and fear the potential to disrupt TV signals, leading them to take a risk-averse approach.

This limits its potential as the big chipset manufacturers are less likely to make products for the lower frequencies – wi-fi typically runs at 2.4 GHz and new protocols are pushing it to 5 GHz and beyond – and this will make it difficult for companies to buy cost-effective kit purely for UK use.

“It needs things to happen on a more global scale,” Webb says. “Ofcom’s actions will help because other regulators can just copy what it has done. But we’re not yet at this point and it’s not clear what it will take to get them there. This leaves a bit of question mark over the white space.”

David Crawford acknowledges this issue, but says there are signs of interest in other countries and that there is a real potential for white space.

“Nobody is saying white space will displace licensed spectrum usage, but it adds a new option. It may be more cost-effective than the licensed approach and technologically more effective than the unlicensed approach, and this could open new business opportunities.”