Huge investment
The technology and application neutral licences will be auctioned off by March 2007.
A similar auction of third-generation (3G licences) in 2000 raised £22.5bn, but left many operators struggling to find a return on their huge investments.
Ofcom has previously said it will take these issues into account when conducting the auctions.
About a third of the spectrum is currently owned by the military, but Ofcom has plans for a gradual sell-off of more than 400MHz of the remainder over the next few years - more than the total spectrum currently used for mobile telecoms.
Buyers will be able to trade the licences with each other, with an initial minimum period of 15 years.
Possible uses for the spectrum include mobile TV services using DVB-H (Digital Video Broadcasting - Handheld) or DMB (Digital Multimedia Broadcasting) technologies and broadband wireless access using WiMAX technology.
