The media regulator has asked the public service broadcasters to submit bids for the fifth HD slot on DTT, essentially Freeview, to join those already available - BBC HD, BBC One HD, ITV1 HD and Channel 4 HD.
Since the Freeview HD platform was commercially launched in May 2010, sales of Freeview HD devices have topped 1.8m in the UK. Coverage of the subscription-free service is currently around 50% of UK households, including Manchester, London, Newcastle, Leeds, Birmingham, Liverpool and the majority of Wales, and that will rise to 98.5% by the end of the digital switchover in 2012.
DTT spectrum is a finite natural resource that is in very high demand. HD spectrum also requires roughly four times as much as standard definition, and getting HD on Freeview was only made possible by the reorganising of existing TV services and the introduction of two new technologies - MPEG-4 and DVB-T2.
The initial plan for Freeview HD was for the BBC to have just one HD slot for BBC HD, with ITV1 HD and Channel 4 HD taking the others. A fourth slot was earmarked for the launch of Five HD, but the now Richard Desmond-owned broadcaster ruled out a launch in March 2010 due to its then financial problems, meaning Ofcom handed the capacity back to the BBC for the launch of BBC One HD.
It is widely expected that Channel 5 will now look to use the extra spectrum for the launch of Channel 5 HD on Freeview, as the channel is already available on Sky and Virgin Media.
Alternatively, the BBC could pitch for the spare spectrum to launch BBC Two HD, or another PSB may seek to gain the valuable capacity, such as ITV for the launch of ITV2 HD on Freeview.
The closing date for applications is October 17 and all bids will be judged against a series of criteria, including "an assessment of how the new capacity will contribute to enhancing the range and diversity of high-quality television services available on DTT". It is expected that the new channel will be ready to launch by April 1, 2012.