08 May 2012
As analogue tv switches off, innovative applications are set to switch on
As the last elements of the UK's analogue television network are switched off, attention is turning to what industry might be able to do with the vacated spectrum, which is being referred to generically as 'white space'.
One of the pioneers in this area is Neul, set up by a number of people who were involved in the early days of CSR. In June 2011, Neul unveiled its first product, called NeulNET, which it believes will 'revolutionise' M2M communications and other wireless applications, such as rural broadband and smart meter communications.
At the time, Luke D'Arcy, vp of marketing, said: "We see a massive opportunity. It's the first time that high quality spectrum has been made available in an unlicensed way."
White space communication will operate in the range from 470 to 700MHz and is expected to offer better performance than Wi-Fi. There are a number of reasons for this, but one major benefit is that, because frequency is lower, transmission distance is further for the same output power. Frequency and time division multiplexing are used to get the most out of the available bandwidth. "While the output power is similar to that of a mobile phone," D'Arcy contended, "a typical location will have access to a bandwidth of 16Mbit/s."
Not only has the white space community inherited the old analogue tv spectrum, it has also inherited the existing channel spacing – 8MHz. This means communications need to be tightly controlled to avoid cross channel interference. Like the signals being transmitted, interference also has a long range.
Unlike Wi-Fi, for example, where interference comes from similar equipment, interference in the white space spectrum can come from devices such as wireless microphones and remaining analogue tv transmissions.
One of the solutions to the interference problems is a frequency management database. When set up, a NeulNET basestation will communicate its location to Neul's management database. This tells the basestation which channels in the area are free and which are best to use.
Developing technology is one thing; finding out whether it works in the 'real world' is another. Addressing this challenge, a number of leading companies – including Neul, Microsoft, Cambridge Consultants and TTP – created the Cambridge TV White Spaces Consortium and have spent the last few months working out whether or not the technology has a future.
The work is being done, in part, in an attempt to alleviate a looming capacity shortage. According to the Consortium, the market for mobile bandwidth is expected to all but double within the next three years, driven by demand for applications such as tv streaming, internet access, voice calling, music services and video downloads. White space is seen as one way of dealing with the problem.
The Consortium chose to trial the technology in Cambridge because of its history in developing wireless technologies. It also offers a diverse environment; everything from historic stone buildings at its centre to outlying villages with poor broadband service.
The test network comprised seven basestations: five distributed around the city, one basestation in a rural location south of the city and a further basestation acting as the network management centre.
Tracy Hopkins, Neul's vp of sales, said the work undertaken by the Consortium has been 'quite exciting'. "The trial began about a year ago to show that white space didn't interfere with primary broadcasts. Interested parties – including the BBC and communications infrastructure specialist Arqiva – have been turning white space into the next generation communications technology."
She admitted the trial wasn't large; rather, she continued, it was simply about proving the technology. "The results," said Hopkins, "look positive; white space doesn't interfere with other transmissions."
Having determined that white space doesn't interfere with other equipment, the Consortium is embarking on a range of trials. At one end of the scale, high quality video and audio content from the BBC and BSkyB will be streamed over the white space spectrum to a range of mobile devices, including some from Nokia and Samsung. But Neul is looking to examine how feasible it is to create the 'smart city'.
"We are looking to roll out applications," Hopkins noted. "This will see many more terminals in the network, consolidating and extending the work done in the initial trial. We're looking for real use cases, rather than demonstrations; things that will make a difference."
The Cambridge wide network will embrace a number of potential smart city applications. One somewhat prosaic application will be to notify the city council when particular rubbish bins need emptying, but one application with particular relevance to Cambridge will be dealing with car parking. "We're looking to create a real time database of where parking spots are," Hopkins said. Other smart city applications could include transport, traffic management, air quality sensors and street lighting; as Neul says 'things, rather than people'.
The initial version of NeulNET launched in 2011 was essentially a technology demonstrator. Now, the company is working on a smaller version of the device. "The terminals are large from an M2M point of view," Hopkins admitted, "but we are looking to reduce them to chip size." The second generation product is 50% smaller than the original, but is still too large for mainstream M2M applications. "But it's small enough to be used in the trials," she added. "We want to connect various white space terminals to a range of equipment, which can then be connected into a network."
One of the applications which Neul has in mind is smart meter reading. Working with Bglobal Metering, it has demonstrated that it is possible to generate a meter reading over a white space network and says it's the first step towards smart electricity grids.
As part of the Consortium trials, TTP and Neul have delivered a broadband service of 8Mbit/s over one 8MHz tv channel over a white space link. The transmission was made between TTP's headquarters in Melbourn and the village of Orwell 5.5km distant. TTP believes data rates of 20Mbit/s may be possible in the future.
"The cost of deployment is significantly lower and faster than fibre over long distances in remote areas," says TTP's head of wireless Richard Walker. "Consumers will simply have to purchase a second tv aerial and a white space router, while we would expect service charges to be similar to those of current adsl costs."
Neul is now looking to install a white space network along part of the A14 corridor – the busy trunk road linking Felixstowe and Rugby, passing Cambridge's northern outskirts. "This is exploring whether white space can deliver integrated traffic management systems," said Hopkins. Currently, such systems use the gsm network to communicate data from vehicle to base.
A tracked vehicle could be fitted with sensors to collect a range of data or a shipping container equipped with a simple identification device. That information could then be transmitted to the nearest white space basestation, which would not need to be by the roadside. "It could be in a nearby village and collecting other data," Hopkins concluded. "Tracking shipping containers could be one of the biggest applications for white space communications."