New regulations clear the way for wireless broadband to use the same spectrum as digital television transmissions
Ofcom has cleared the way for the deployment of broadband Internet devices using the same radio spectrum as digital television, with regulations that came into force on New Year’s Eve.
The regulations, first announced in February, mean that devices no longer need a licence to operate in the gaps – or “white spaces” – in the 470 – 790 MHz spectrum band used by digital television broadcasts.
“Based on the trials and stakeholder feedback, there is considerable interest from industry in developing this technology,” Ofcom stated. “Ofcom also plans to explore whether the white space in other spectrum bands could be used for similar innovation in future.”
The white spaces exist because high-power television transmissions need them to prevent interference. However, lower-power devices can make use of the gaps without posing a danger to existing signals, and professional radio microphones and other devices have done so for “a number of years”, Ofcom said.
Signals using the frequency can penetrate obstacles such as walls, buildings, foliage and landscape features better than the 2.4 GHz frequency used by Wi-Fi, making it practical for providing Internet connectivity across city neighbourhoods or in unconnected rural areas.
White-space technology has been used in North America to provide broadband connectivity to university campuses and residential areas, and it has been trialled for several years in the UK.
White-space devices can now be used without a licence in the UK and the Isle of Man, provided they meet certain technical requirements intended to ensure they don’t interfere with existing signals, such as a restriction on their transmission power, Ofcom said.
Such devices must also link to a database that checks which white spaces are available in the current location and switches the unit’s transmitters to make use of those gaps. The database is made available via partners including Nominet UK and Sony Europe.
“To avoid harmful interference being caused to existing spectrum users, devices will need to communicate with databases which will apply rules, set by Ofcom, to put limits on the power levels at which devices can operate,” Ofcom stated.
White-space devices may be fixed or mobile, Ofcom said.
White-space broadband Internet standards efforts currently under consideration include IEEE 802.11af, IEEE 802.22 and proposals submitted by the White Spaces Coalition.
The current deployments in North America involve linking a Wi-Fi router to a service provider using white-space spectrum as the backhaul.
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