Since the very first radio transmitters went on the air at the dawn of the twentieth century, we have been rather obsessed with control of the RF spectrum. Rightly so in terms of potential interference; wrongly so in terms of political control. Governments in the 1920s through the 1950s were terrified that radio would become a subversive force that could be turned against them.
Licensing started early on and was given out for transmissions of a particular modulation, at a particular frequency, at a specific power, at a specific location. As technology evolved, the spectrum effectively increased, as we were able to go to higher and higher frequencies. But the licensing model changed little.
I am personally in favor of anarchy in the spectrum; it has been shown to work time and again. In the UK it worked when stodgy BBC radio programming failed to cater to teenage music pressure. Radio Luxembourg filled the gap and, most evenings, you could get a clear AM signal in the South-East of England. Then came the offshore pirates operating from ships and Martello Towers. Quickly, very quickly, the BBC changed and commercial licenses also started to be issued.
The same happened in Italy when viewers got fed up with the programming from the state broadcaster, RAI, leading to rampant video piracy and resulting changes, with commercial networks growing in competition.
But the changes didn't make any difference to the way licenses were looked upon. There is still only FM broadcasting in one VHF band; only TV in specific VHF and UHF bands; only microwave links in certain other bands -- well, you get the picture.
This was all very well for the lengthy period of time when technology did not change that fast. It is a real pain now, particularly with the proliferation of wireless devices and systems that seem to be in continual flux. In the UK, a way forward is in progress. It is being called "spectrum usage rights" (SURs). It takes the basic premise of a license (licence in BritSpeak) and turns it on its head. Instead of saying that you can use so much power at a particular frequency, it says how much interference you can cause to another user, even if he is employing a completely different modulation scheme, even with different bandwidths.
After the release of the consultation document in April 2006, Ofcom (Office of Communications) received comments from stakeholders over a couple of months and made some implementation next steps, but the system is accepted by all as doable, with the task coming up being how to define the different interference models, whether the interference is in-band or not.
Rather than trying to change existing license holders' conditions, Ofcom will wait for the next round of frequency allocations (by auction) and will then implement SURs allowing each user to define their own networks, with their own technology, without having an Ofcom policeman lurking in the corner of the basestation. From a revenue point of view it is anticipated that another billion Euros will enter the UK Government's coffers from the flexibility it will bring to the spectrum.
The next chunk of spectrum is likely to come in the UK from the turn-off of analog(ue) TV, which will begin regionally in 2008 and be history by 2012. By then, it is expected that the vast majority of users will receive Freeview TV which offers about 50 over-the-air digital channels. Want more? Subscribe to cable or a satellite service. Unlike the US, the UK turnoff is on a schedule that is not going to change and the amount of UHF spectrum that will be released is huge. You can do a lot with nearly 400 MHz. The UK won't be the first -- Dutch analog TV is already history.
But let's not stop at 400 MHz. Think small - what could you do with 1 MHz? A whole bunch of radio broadcasters in the US who have both AM and FM licenses want to jettison their AM services. Nobody is listening, they say; HD-Radio is a dud for directional antennas; the transmitter utility bill averaged per listener is daunting; the license fees are heavy.
If the AM band was evacuated in, say, five years, what could we do with it? Are there any narrowband wireless applications left?
