The proposed upgrade to the digital terrestrial television network would create capacity allowing HD channels on Freeview as early as 2009.
Ofcom said the upgrade could be completed in time for digital switchover in the Granada television region, which is due to take place in late 2009 to early 2010.
The new services would then be available while switchover was rolled out across the rest of the UK, completing with four HD services being available by 2012.
“Viewers who wanted to access the new services on offer would need to buy a new DTT set-top box or integrated television, which was compatible with MPEG4 and DVB-T2,” Ofcom said today.
“However, viewers with existing DTT set-top boxes or integrated televisions would still be able to access Freeview services with their current equipment.”
The media watchdog also expected the upgrade to bring benefits worth four to six billion pounds to the UK economy over 25 years, by making better use of the spectrum reserved for broadcasting.
“Our proposals to upgrade Digital Terrestrial Television represent a major opportunity to build on its success with wider, richer and more varied television services, including the potential for HDTV to be made available to millions of people free to air,” said Ofcom chief executive Ed Richards.
“We look forward to hearing the views of viewers and from right across the industry.”
The proposals come on the back of BBC, ITV, Channel 4 and Five signing a preliminary agreement to deliver HD channels on Freeview by the completion of digital switchover.
The four terrestrial broadcasters signed a non-binding deal which could see them share space on Freeview multiplexes in order to offer HD services to viewers by 2012.
More than 14 million UK homes are now using Freeview, the company confirmed yesterday (20 November).
The consultation will close on 30 January 2008.
Ofcom will publish results in March. After that it will invite broadcasters to make channel launch applications.