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White Space trial: First Cambridge, then... THE WORLD
|27 апреля 2012|
Despite blanketing Cambridge with trials, and White Space kit becoming legal in the USA, the White Space Summit in Duxford yesterday was still focusing on trying to convince the world that the technology will change everything – and for the better.In the UK, White Space devices should be legal around the end of 2012, and yesterday marked the end of extensive trials of the technology across Cambridge. But in much of the world the idea of filling the gaps between TV channels with unlicensed radio transmitters is greeted with all the enthusiasm of a Dolly Parton fan confronted by a dancing telephone.
Dolly Parton, along with the evil dancing telephone above, was enlisted by the National Association of Broadcasters in its campaign against White Space, which detractors said would interfere with television broadcasting and knock out wireless microphones. Despite it being completely legal to use White Space in the US, the campaign did prompt the FCC to impose some fairly draconian limits on the power and frequencies that White Space devices could use: tellingly, even working within those limits, the technology has decisively proved itself.
White Space exists because the frequency being broadcast TV in, say, London can't be used in, say, Oxford, as the huge London transmitter would interfere, but on the far side of the Oxford transmitter the London frequency is empty – white – and can therefore be used for other applications without impacting the TV reception. White Space devices have to check with an online database for locally available frequencies, but a single hub can do that and pass the message on to its client devices.
In the UK we're only just behind America in White Space deployments, and we're also ahead in the applications being considered and demonstrated in Duxford. White Space frequencies have excellent propagation, they waltz through walls and echo over hills like a ghostly Maria, which is why they were chosen for TV broadcasting back in the days when whole spectrum was available to pick from, and those properties have pushed them into wireless internet access.
Deployments in the US have focused entirely on that, providing connectivity to an entire town or an oil field without needing line of sight. A single White Space base station can provide decent internet access – 4Mb/sec – to 10 homes up to 8km away. At the summit, TTP's Richard Walker demonstrated how the low cost of even the second-generation White Space kit now in production makes that a viable business.
That's also the model being espoused by OpenReach and several other companies, but Cambridge-based Neul has greater aspirations.
Neul wants a national network supporting machine-to-machine communications, and given that no one else has stepped up, it has decided to build a few city-wide examples. Neul developed Weightless, a protocol specifically designed for M2M applications which has now been passed to a Special Interest Group for development, but is still convincing people just how important such things can be.
So the test network Neul deployed in Cambridge for the trial will get expanded to seven or so base stations, rather than being dismantled, and it will switch to the Weightless protocol so the company can deploy intelligent litter bins, which know when they're full, and parking spaces, which know when they're empty, along a host of similar applications. Another UK city or two will get the same treatment over the summer, and the project is planed to go international (well, transatlantic) by the end of the year.
The idea is to have billions of intelligent devices with $2 chips speaking Weightless, a protocol so efficient it drains a battery no faster than it would naturally decay (about ten years) though with a speed and latency which make it unsuitable for typically-impatient humans.
There aren't any $2 chips yet, of course. Neul reckons to have silicon designed by the end of 2012 and in production 12 months later – so the extended trials will have to use the $200 second-generation versions which are about the size of a cereal packet. Neul doesn't want to make silicon at all, it wants to run the network and provide the IP, but there won't be a network without devices and their value still has to be proven.
M2M probably is the big market for White Space, but it will be rural broadband which claims the headlines for a few years yet; it answers a pressing need and produces smiling grandparents Skyping adorable children, as opposed to cheaply emptied bins, which make for poor television footage.
But 4G networks can also provide rural broadband, as demonstrated by BT and EE in Cornwall, and cheap microwave kit is already straddling the Welsh mountains to link up distant relatives. White Space might be a bit cheaper, but it's not world-changing in those applications.
Where White Space shines is in applications that can't be achieved in other ways: monitoring air quality or measuring traffic flow in real time, things that will ultimately prove just as important as Skype but are a harder sell than an offer of a cheaper way of doing what we already do.
Источник: The Register