Brits are unlikely to benefit from 4G networks until 2015, Ofcom has warned.

According to the regulator's Draft 2012/13 Annual Plan, next-generation mobile networks won't be "widely available" for another three years at least.

4G networks utilise the 800Mhz and 2.6Ghz radio spectrums, which are currently used for television broadcasts, to offer faster mobile broadband services, with speeds thought to be as much as 'up to' 100Mbps. 4G networks will also be able to cope with a greater capacity than existing 3G services, as use of mobile broadband increases. The 800MHz band is currently used for terrestrial TV broadcasts, but the digital switchover means it can now be assigned for mobile broadband use.

These spectrums will be auctioned off to the UK's mobile networks. Initially, Ofcom said the auction would take place at the beginning of 2012. However it has now revised its timescale and moved the auctions expected start date to mid-way through the year following the threat of legal action by O2, which claimed auction was illegal under EU law. O2 believes as itself and Vodafone already own some 900mhz spectrum, Ofcom will ensure a certain amount of new 800mhz spectrum goes to their rivals, but says the two spectrums aren't directly comparable and the move would give their rivals an advantage when all operators should start with a clean slate.

Ofcom is continuing to claim it will hold the auction for the 800Mhz and 2.6Ghz spectrums in the 2012-2013 financial year, although it's subject to clearing the spectrums and ensuring the services that use the 800Mhz band are moved to another spectrum.

Mobile networks including O2 and Orange are already trialling 4G networks in the UK.