Published:
25-Nov-08
On November 4 2008, the US Federal Communications Commission (FCC) approved unanimously a measure to open up national 'white space', the signal area around and between terrestrial television scattered throughout the 200-800MHz range (VHF and UHF). Due to the nature of US network transmission, locally there tends to be a number of "free" channel slots, which can be utilised by other applications. Since this patchwork of signal space is not consistent across the country, and often sits directly next to or between active DTT spectrum, the dual issues of interference and tracking across free spectrum for mobile devices have been contentious.
The final run-up to digital switch-over, in February 2009, has seen large tech companies, notably Microsoft, Google, Philips and Motorola endorsing the open use of this spectrum. This has been widely and publically contested by broadcasters, mobile phone operators and users of wireless microphone technology, such as stadiums, theatres and mobile news production, primarily concerned about the interference from consumer devices operating in white spaces. In addition, mobile operators have expressed concern that an open spectrum will compete with expensive walled-garden infrastructure around mobile networks. The FCC decision to allow open usage within this sensitive part of the spectrum is in the hope of replicating the innovation and spend following the success of unlicensed wireless devices in the public 2.4 GHz frequency in the nineties- now an industry worth in excess of $30bn and spawning remote control cars, DECT phones and Wi-Fi internet.
In an effort to legitimise the move, the FCC will certify all white space consumer devices, which will be required to operate at a low output, especially when in frequencies near active channels, and to employ technology to recognise active spectrum in order to avoid interfering, technology which the FCC has currently only put through technical trial, without much success. Part of this will include an online database of locations sensitive to white space interference, such as broadcast transmitters, cable headends and production locations such as stadiums. While proof of concept has not been easy to come by, the hope is that these will pacify the incumbent while allowing innovation from new entrants in the CE space.
Our take...
The furore about the use of white space is not a new development, and has been in some form for over four years since first suggested to the FCC. The VHF and UHF frequencies which house terrestrial television are arguably the most valuable space in any country's spectrum since signals are high enough to carry large amounts of data to relatively small antenna, but low enough to be robust for use in terrestrial transmission at near line of sight, making network build cost relatively low compared to higher frequency technologies.
While the FCC ruling might suggest a brave new world, it is far too early to say how much success vendors will have in adopting the stringent rules to seamlessly slip into already crowded frequencies. While in its infancy, the promise of more efficient usage of terrestrial spectrum is an exciting prospect, with many portions of spectrum allocated to niche uses which might be paired up with another usage which doesn't directly compete, such as several defence frequencies or maritime radar. The technologies required to implement the white spaces ruling might allow further use of narrow capacity which currently sits unused in the overall spectrum.
USA,
