Ofcom has recently launched a consultation on the use of 'white spaces' – those portions of the electromagnetic spectrum which have been allocated for communications but which are not utilised in all geographic locations or are unused for part of the time. Recent developments in spectrum sharing mean that some devices can change their frequency use in response to external drivers, known as dynamic spectrum access, to accommodate the needs of other spectrum users or to avoid harmful interference. Ofcom's consultation focuses on the use of the ultra-high frequency TV band, between 470MHz and 790MHz, as this is the first range in which dynamic spectrum access will be authorised. This range is currently used for the broadcast of digital terrestrial television.
The availability of white space is very much subject to geographical location, the performance of the white space devices concerned, and the broadcast power at which they operate. Ofcom gives the example of Central London, where the best performing devices would have access to nine or more frequency channels in 100% of households, whereas in Glasgow, in around 60% of household the devices would be limited to three or more channels.
Although Ofcom intends to err on the side of caution during the early stages, there remains the potential risk that the use of dynamic spectrum access by white space devices may interfere with television services. However, the benefits may outweigh the risks, with services such as hotspot coverage (like WiFi); in-home broadband and multimedia distribution; rural broadband; and machine-to-machine ("M2M") communications potentially benefitting.
A solution for the efficient use of TV white spaces is expected to be rolled out in late 2014, but before then a pilot will be conducted involving trials around the UK by a number of different service providers. This will enable the systems and processes (including regulatory processes) to be tested. For the purposes of such trials, licences will be granted to particular operators, although following full rollout the white space devices will be licence exempt and available to use in the home.
The consultation period for the pilot closes on Friday 15 November 2013 – interested parties can respond here. The full consultation document is available here.
By Chris Eastham and Paul Barton