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Don't kill FM for broadband: Build a new internet

Ofcom is planning a digital switch-off for FM radio and eyeing the frequencies for more broadband services. An exciting alternative is already available
Written by Rupert Goodwins, Contributor

Although the move from analogue to digital wireless has seen many new and exciting services, the process of clearing old services is slow and expensive with little innovative in their place. So how about free ultra-reliable nationwide wireless broadband on unused frequencies that are available now?

There's not much sign that big ideas are on the agenda yet. According to The Wall Street Journal, Ofcom is considering liberating the radio spectrum that carries FM stations and giving it over to broadband. The thinking goes that with the move to digital radio, up to 50 percent of the band between 88 and 108MHz could carry wireless data; the frequencies are good at going long distances and penetrating buildings, making them especially suitable for rural areas.

Unfortunately for Ofcom, the FM band is also really good for broadcasting. With FM radios available new for a couple of pounds upwards, universally installed in cars, and capable of receiving four national BBC networks and 10 or so local and independent stations, it's no surprise that the public has been cool towards moving to the new digital radio stations. Also, it's been a long, expensive and complicated ride for the digital switchover for television: there are many times more radios than TVs in households and no real reason to turn them all off.

Band I

Ofcom's argument is that there is huge pressure on spectrum for new services, so the old must give way. Yet this has already happened. Down below the FM waveband, between 30-88MHz, is a nearly forgotten chunk of spectrum called Low Band VHF, or Band I. (FM is Band II, while DAB — digital audio broadcasting — is in Band III, at around 200 MHz.)

Old radios

Rather than eating into FM frequencies to create more wireless broadband, why not delve into the Band I spectrum? Photo credit: bestfor/richard/Flickr

Originally used during the war for Chain Home radar and Bomber Command communications, Band I became the home for two-way radios for the military, the Fire Brigade, the Gas Board, the AA and so on, though the major incumbent was black-and-white 405-line TV. The band was largely vacated in the mid-1980s when the last 405-line TV transmitters were turned off for economic reasons.

By now, the two-way radio traffic, military and otherwise, has largely departed to new, digital systems; apart from a new amateur radio band and a scattering of things like baby alarms, Band I has sat there unloved ever since. Even with gaps for the remaining services, that's getting on for 50MHz of bandwidth, silently waiting.

It does have problems. The lower the frequency, the longer the wavelength; while mobile phones use frequencies with wavelengths of a few tens of centimetres, allowing compact antennas, Band I starts with three-metre wavelengths and goes down to 10 metres. You can use small antennas, but they're not very efficient. Also, as the bottom of the band is close to shortwave frequencies, it's more affected by atmospheric conditions, including anomalous long-distance reception.

But otherwise it's really useful. In-building and past-line-of-site coverage is better even than Band II, it's not particularly prone to atmospheric noise, and it's free. You don't have to boot off The Archers to use it. Still, it's avoided commercial pressure: the other chunks of spectrum are easier to use for mass-market money-making systems, and that's where the focus has been.

It's when you divorce yourself from the model of spectrum being primarily a revenue generator and look at it as a national resource that the game changes.

Mesh network

One interesting model would be a national open mesh network (or "Nomen": why not?). Mesh networks work by each station also acting as a router, relaying data from surrounding stations and steering it towards its destination. As stations appear and disappear from the network, it adjusts the map it has of itself, so each station always knows the most effective way to send messages on.

The system could work by having individuals install a Wi-Fi-to-Band I gateway that automatically configures itself to connect to its nearest neighbours. The range is good enough that a few stations dotted around will have a footprint sufficient to make it worth others joining, and home-based systems will have plenty of room for a discreet external antenna.

One of the secrets of mesh is that the more people join in, the greater the frequency re-use and the greater the bandwidth available, so the more people who use it, the more attractive it becomes to others. Once there's a bit of interest, it will build quickly.

This would produce a large, cheap and above all infrastructure-free network that could operate largely independently of any other wired or wireless system. Gateways into the internet would provide the connectivity most people need, but hosting your own data or running your own services — even in the event of a major network failure elsewhere — would be very viable.

Even remote communities could be part of the mesh, just by pointing a directional antenna at the nearest station: the engineering is simple and cheap enough that community effort will be more than enough.

Hard to jam and easy to reconfigure, it would be unperturbed by anomalous propagation, as stations appearing and disappearing are natural to mesh topology. In terms of a useful addition to the national infrastructure, it would add a new, independent and supremely flexible layer of connectivity, and it would provide the lowest possible cost of access for the digitally disadvantaged.

Low cost

How low a cost? It'd be an extra chip — if that — in a Wi-Fi router; all the protocols and engineering have been done and are freely available, and with no infrastructure there are no bills to pay. With nobody trying to squeeze money out of the system, it will be free to develop along the lines of maximum utility, effectiveness and efficiency, and the engineering is well within the reach of the sort of open hardware experts who have already built an open-source GSM system. A single payment — £50, say — and you're done.

It would never replace the megabits of 3G or cable, but then that wouldn't be its job. Cheap, reliable, usable and flexible: it would be the original internet reborn.

And we could start doing it tomorrow, by Ofcom declaring a chunk of Band I open for business with the lightest of regulatory touches.

All it takes is vision and will. Over to you, Ofcom.

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