Fancy being a mobile phone operator, but don't have ten billion pounds to spend on a licence? Want to run your own network, but don't know any major footballers happy to endorse your product? Your chance may be coming up -- and it's all due to an obscure piece of radio regulation called a guard band.
The story starts in the early 1990s, when the digital GSM mobile phone system was showing signs of doing rather well. Back then, it coexisted with analogue mobile on the 900MHz band, but room was tight and new operators were champing at the bits. So a new band was needed. It wasn't the only one -- digital cordless phones were coming onto the market, and they needed a home in the spectrum too. Europe decided to allocate two bands at around 1800MHz, one to a variant of GSM called GSM1800 and the other to the digital cordless standard, DECT. The two services sat right next to each other -- too close for comfort.
One of the many problems in radio design is coping with unwanted signals close to the ones you're after. Too strong a signal nearby, and your radio can get temporarily deaf -- desensitisation, in other words. You can also get a wide variety of interesting spurious virtual signals appearing in your band, which aren't there really but get created inside your radio from bits and pieces of others. It can be quite a mess, even after you've worked out what's happening: a lot of the reported unreliability and compatibility issues with 802.11b cards are due to poor radio design causing problems like this.
With GSM 1800 and DECT, the RA decided to play it safe. You can't get problems with strong signals next door if nobody's allowed to transmit there -- and so, a 3.3MHz-wide guard band was left fallow between the two services. Result: happiness.
That was then. These days, unused spectrum attracts attention like a fresh ox carcass in the desert attracts vultures. Every idle Hz is under review, and the GSM1800 guard band is too tempting to leave. Radios are better these days than they were, and the RA has done some tests that show there's not much chance of any problems if the band is reused -- besides, other European countries never bothered with it, and they're fine. So what shall we do with our megahertz?
There are three main options. One is to do nothing: the band and the rest of the GSM1800 allocation is due to be turned over to 3G usage at some point, so why bother fiddling in the meantime. Also, it turns out that it's not as empty as the band plan makes out -- because it's so close to the mobile phone frequencies, the RA has been handing out test and development licences to the phone companies to let them fiddle about on-air, so that could just carry on. Another option is just to hand it over to the GSM bods for commercial use, either for a new operator or as extra room for the existing four. That'd be easy, useful and quick. The third option is the most intriguing: turn it into an effectively unregulated GSM band.
What the RA envisions is you, me and the bloke next door being able to go out and buy our own cell base station. In the office, this would turn everyone's mobiles into extensions on the work phone system -- something that's been promised for many years. At home, it means you won't need another cordless phone, and you can switch automatically between being on your mobile network and your landline. Again, something that's been on the cards for ages but never rolled out. Commercially, retailers can offer a phone service with advertising via SMS when you're out shopping, but the way would be open for villages, streets and other ad-hoc communities to deploy their own effectively free mobile phone system at the drop of an antenna.
It would be a brand new kind of phone service, one with the massive advantage that everyone owns the access terminals already -- fifty million handsets in use in the UK. Base stations might look big and expensive, but GSM technology is now so mature and cheap that you can build one the size of an ordinary modem and costing not much more. Stir in broadband and voice over IP, and we the people can build international, low-cost mobile communication networks overnight. Blimey.
The deal's not done yet -- there are lots of other things to think about, but it's clear from the RA's consultation document that someone's rather keen on the idea. We've got until the end of July to respond, so if you've got something to add to the debate you should hurry on over to the appropriate document and chip in. You might even get to put your name on the football shirts of your local Screwfix Direct Western League team -- why should Vodafone have all the fun?
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