The A to Z of wireless

S is for Spectrum

Radio spectrum is the Kate Moss of the wireless world - many people desire it; few can afford it; fewer still will ever get a whiff of it. But it's powerful and valuable stuff: UK telecoms regulator Ofcom estimates business activity that is largely dependent on spectrum contributes £37bn, or three per cent, of the UK's GDP.

Ofcom is tasked with overseeing UK spectrum usage to, among other things, prevent interference between different wireless devices. It also runs auctions to sell swathes of spectrum when it becomes available.

The characteristics of spectrum bands vary - with some being more desirable to power mainstream comms technologies owing to the radiowaves' ability to travel long distances and more easily penetrate buildings. For instance, the likes of FM and digital radio, mobile phones and satellite TV operate in the higher frequency bands (between 30MHz to 30GHz), with very low frequency bands reserved for niche uses such as submarine comms.

Ofcom dubs spectrum below 15GHz as "the most sought after and congested frequencies". But arguably the most valuable spectrum lies in the so-called sweet spot of the UHF (Ultra High Frequency) band: the 300MHz to 3GHz tranche.

One UHF section, in the frequencies 470MHz to 862MHz, will soon be freed up for auction by the switching off of the analogue TV services in 2012 as television broadcasts go fully digital.

This spectrum, known as the Digital Dividend, is particularly attractive to mobile operators as the longer wavelengths would mean a network using the spectrum would need fewer base stations to generate a good signal - ergo cheaper network infrastructure. The spectrum's in-building coverage is better too.

But it's not just mobile operators that the Digital Dividend could appeal to: suitable uses for this spectrum could include WiMax, mobile television and broadband, local TV stations and additional Freeview channels, according to Ofcom.

Unlike some of its previous spectrum auctions the regulator has decided to auction the Digital Dividend spectrum on a "service-neutral basis", so technology developments that could use the spectrum aren't hamstrung by restrictions on what it can be used for.