A trial at London Zoo has paved the way for Ofcom guidelines on using the unused “White Space” parts of the radio spectrum in the 470 to 790 MHz frequency band.
Three webcams were set up: two in the meerkats' home and one in the otters' enclosure. All three were linked to a web server using White Space radio as TVWS – TV White Space.
Normally the process of hiding the cameras in the enclosure behind trees and tyres would mean a poor radio connection but, because White Space is at a lower frequency than Wi-Fi, the signal propagation is better. TVWS signals are able to penetrate foliage and buildings to establish a fast data connection capable of streaming high quality video to YouTube.
The current denizens of that spectrum are Digital Terrestrial Television (DTT), including local TV, and Programme Making and Special Events (PMSE), including in particular wireless microphone users. Yet, much like the meerkats in the zoo, they are not using all of the space all of the time, so local sparrows might nip in and have a scratch around.
With White Space radio things are a little more regulated. The sharing will take place dynamically, controlled by databases which will hold information on the location of DTT and PMSE users and White Space devices. They use this information to allow White Space devices access to the spectrum band, but only to the extent that this does not cause harmful interference to the existing users of the spectrum.
This is the first time Ofcom has decided to implement spectrum sharing using a database approach.
How all this will be done is laid out in a new Ofcom document (PDF).
Equipment for White Space use is largely still in the early stages of development. While there is an ETSI harmonised standard, and Ofcom will specify minimum technical requirements that equipment must meet to operate in White Space, the organisation admits that they do not yet know what the actual characteristics of mass consumer White Space equipment will be.
“All this provides a high degree of uncertainty about how use of White Spaces,” say the authors of Ofcom's Implementing TV White Spaces document. “The market in White Space devices will develop and we therefore have taken the view that, to begin with, we need to set our protection criteria in a conservative way.”
The applications which were looked at in the experimental stage included public Wi-Fi, webcam backhaul, rural and maritime broadband services, remote sensing, academic research, digital signage, local broadcasting and CCTV distribution.
We've been waiting a while for all this. In November 2012 we reported predictions that it was a year away.
The meerkats can be seen taking a break from selling insurance here. ®