Tech giants are using Cambridge as the test bed for new whitespace broadband technology.

Microsoft is leading a consortium of Internet Service Providers, including BT and BSkyB along with the BBC and Nokia, in whitespace technology trials in Cambridge to evaluate how it works in rural and urban areas.

The Cambridge TV White Spaces Consortium also includes tech design houses TTP and Cambridge Consultants, new Cambridge wireless darling Neul, Samsung and Spectrum Bridge.

The consortium issued a statement saying: “With the number of connected devices and data applications growing rapidly, and with mobile networks feeling the strain, we must find ways of satisfying the traffic demands of today and tomorrow.

“This trial will attempt to demonstrate that unused TV spectrum is well placed to increase the UK's available mobile bandwidth, which is critical to effectively responding to the exponential growth in data-intensive services, while also enabling future innovation.”

Whitespace employs unused frequencies between TV broadcasts which are left empty to avoid interference. The consortium believes this unused spectrum can be viably used to provide broadband services.

As Cambridge Consultants revealed to Business Weekly last November, the frequencies used (470MHz-790MHz) are much lower than those utilised by regular Wi-Fi, the signals can travel much further, and are able to penetrate further into buildings.

Neul – headed by CSR co-founder James Collier – and one of the companies in the consortium, says it has a production-ready system which can deliver up to 16Mbps at a range of 10km.

Cambridge Consultants unveiled the opportunity to Business Weekly last year and said it was homing in on a share of a $100 billion wireless marketplace with a revolutionary approach to maximising the digital dividend. It said that while major players like Google and Microsoft were seeing whitespace as a potential goldmine, Cambridge Consultants was championing a cognitive approach to solving a whitespace dilemma.

Cambridge Consultants commercial director, Tim Fowler, said the TV spectrum was prime; it was chosen because it has “very nice propagation characteristics and is a very good spectrum for wireless communication.

“But you need to ensure that secondary users are not going to interfere with the primary users. You can do that in two ways; one by detecting they are there – a cognitive approach – listening to see if there are people in the band and making using of it if there’s nobody there.

“The alternative is a database look-up solution; you know exactly where you are and can inquire in the database and ask if there is anyone using spectrum in this area.

“The FCC in America ran a number of tests on the cognitive approach and  found nothing that worked to their satisfaction and so have erred on the side of a database look-up mechanism. The problem with that is it imposes a number of constraints; if you want to use the spectrum to connect you to the internet you need an alternative technology available to check the database to see if you can connect to the internet. If I want to use whitespace to connect to the internet I don’t have any way of checking the database until I’m actually using the spectrum.

“We believe the best solution is a combination of the two; you would probably struggle to keep a database up to date sufficiently and know enough to make a database useful. You’d end up prescribing some fairly aggressive rules in a database if you don’t have any way of learning how good that data is, which will counter the whole point of having secondary use of the spectrum.

“We have some novel technology to detect users in a spectrum. It’s a good cognitive approach. The regulator doesn’t want the spectrum to lie fallow; it’s a national asset after all. But from numerous tests a significant ammount of the spectrum appears to be unused in a number of places.

“The advantage of a cognitive approach is that it is more dynamically allocated based on people needing to use it and ensures more efficiency throughout the spectrum. Our whitespace initiative is a pioneer in this change of regulatory approach.

“We are probably at the same stage with whitespace as we were with 2.4Gb in 1985 when the FCC first said people could communicate in the 2.4 GB. People had been using 2.4 gb for other uses for a very long time - predominantly industrial heating and then microvwave ovens. You couldn transmit and receive in band.

“Then in 1985 everything opened up. And by the early ’90s some proprietary technologies were coming out. The original thought behind 2.4gb was that maybe some garage door openers or things like that might appear in the space. By the end of the ’90s WiFi was starting to emerge.

“We now have WiFi, Bluetooth, Zigbee - a whole range of things occupying that 2.4 gb; it’s a mssive volume market and heavily used. It’s pretty congested now. So we’re 25 years after that initial regulatory step today. It was 15 yrs after the spectrum was opened up that Bluetoth emerged.

“Whitespace is at a similar embryonic stage; I’m not saying it will be 25 years before we know what will happen but it’s very early stage. Our cognitive detection approach could operate in any band to sense if a spectrum is free. That’s quite a challenge because of the hidden node problem.”

In wireless networking, the hidden node problem occurs when a node is visible from a wireless access point (AP), but not from other nodes communicating with said AP. This leads to difficulties in media access control. A and B can each communicate with the hub, but are hidden from each other. Cambridge Consultants has relevant technology today and can demonstrate that it does the detection.

Fowler said: “I think our solution is a potential turning point because it moves from a wholesale allocation of the spectrum to users to a dynamic allocation of spectrum to users. While it’s only curently prescribed for the TV band, our solution could become the way all spectrum is regulated.”

Cisco estimates that by 2014 global data traffic will increase 39 times, reaching 3.6 exabytes, or 3.6 billion gigabytes per month.

• Photograph shows: Cambridge Consultants commercial director, Tim Fowler