The wireless spectrum crunch, illustrated

by Sebastian Anthony, extremetech.com
January 23rd 2013 2:18 PM

Unless you’ve been locked away in an isolated Montana cabin for the last few years, you’ll have noticed that radio frequency allocations are serious business. A few kilohertz here or a few megahertz there can cost billions of dollars to acquire, make or break a mobile carrier, or render the Global Positioning System — and the US military’s ability to use targeted munitions — null and void. What you probably don’t know, though, is why it’s so hard to get your hands on a block of radio spectrum.

The two images below should give you a better idea. The first chart shows you the frequency allocations in the US; below that is the UK. Note that both have very different color keys, but otherwise they’re the same format, starting with the lowest frequencies in the top left. I strongly suggest you open the original PDFs [US / UK], so that you can make out all of the detail.

Beyond the huge blocks of spectrum dedicated to broadcast radio, TV, and satellite, the first thing you’ll notice is just how many different allocations there are. If you zoom in, you’ll notice that these aren’t even specific allocations for companies or institutions — merely categories, such as mobile, fixed, and broadcast. Within each block, the US (FCC) and UK (Ofcom) might manage dozens or hundreds of individual licensees.

Next you should look at the thin, colored bars beneath the larger blocks that indicate whether the spectrum is allocated for civilian, governmental (military), or mixed use. On both charts, red indicates government-only use — and as you can see, both the US and UK governments have an awful lot of reserved spectrum.

It’s also interesting to see just how many categories there are. Not only are large blocks reserved for amateur radio (ham), but also for amateur satellites. There are blocks allocated for space research (astronomy), space operations (communicating with ISS, Curiosity, etc.), and inter-satellite comms. For some reason (probably historical), huge swathes of the lowest frequencies are reserved for maritime mobile comms. In both the US and UK, allocations start to get really crazy around the 1GHz mark — a sweet spot where signals can penetrate obstacles, but where there’s also enough bandwidth for large amounts of data.

We’ve spoken a lot about the spectrum crunch on ExtremeTech, but after looking at these charts it’s clear that there is a lot of spare spectrum out there, and a ton of bandwidth — the blocks and allocations just need to be moved around a bit. The problem, of course, is that most of these allocations have existed for decades, and updating or replacing the relevant software and hardware just isn’t feasible. As mobile communications continue to grow, though, I suspect the FCC, Ofcom, and other regulatory bodies around the world will finally get around to cleaning our radio frequencies up.

Now read: The secret world of submarine cables

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