New TV white space technology could help to fill the communications gap and realise the vision of a global smart grid, believes Cambridge-based TTP, an independent technology development company.
White space has the potential to deliver information at high data rates over long distances, with low latency and at low cost, making it ideal for applications ranging from smart metering to distribution network automation and demand response signalling.
Like the white spaces between words on a page, spaces that carry no information also exist in radio spectrum across frequency, time and space domains for the same reason – to minimise interference. In particular, empty channels and guard bands in the television spectrum offer sufficient bandwidth to carry rich information with excellent signal propagation – as long as there is no interference.
TTP has already been achieving speeds of greater than 8Mbps over a 5.5km white space link using a single TV channel, compared to wired ADSL broadband that can struggle to achieve 2Mbps with less than half the range. White space devices with real time intelligence communicate with a central database in order to tell them which frequencies and powers they must use to prevent interference with the broadcast TV signals.
“Currently, data backhauled from some smart meters might use three or even four different communications technologies en route, from powerline and fixed ADSL to cellular radio and long range point-to-multipoint radio,” says Mathew Palmer, business development manager for Communications at TTP. “White space offers an exciting alternative that takes advantage of unused spectrum and meets the future smart grid communications challenges at low cost.”
Regulators have indicated a preference for the use of white space without the need for licensing; so in effect the use of the spectrum costs nothing in the same way as for WiFi, Bluetooth and Zigbee. And TV white space spectrum sits in a ‘sweet spot’ where bandwidth, signal propagation and antenna size are all attractive for smart grid applications.
In the US, the regulator FCC has already acted to allow the use of white space devices without a licence. In Europe, the UK’s Ofcom has recently announced it intends to allow white space devices to operate licence-exempt, and regulation is expected to be in place to allow technology deployment in 2013.
“The technical challenges are being solved so the task in hand today is convincing the licence holders and regulators worldwide that licence-exempt white space works for everyone on a global scale,” adds TTP’s Mathew Palmer.
