Espectro

The Great Spectrum Famine
MOBILE BROADBAND IS CONSUMING THE AVAILABLE RADIO SPECTRUM. SERVING UP MORE WON’T BE EASY By Mitchell Lazarus

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SPECTRUM.IEEE.ORG

Not even sci-fi writers foresaw what we’d be doing with our phones once technology put color screens and a lot of computing power in our pockets.
Now we know: We use them to stream YouTube andFacebook videos; we watch TV shows; we download and store songs and movies; we take pictures of everything going on around us; we read (and some of us even write) novels; we play video games; we surf the Web. Sometimes we even talk to each other. These days you can unleash a gusher of bits over the air that would have choked even a wired connection to the Internet not so long ago. Thesetransmissions consume radio bandwidth—lots of it. And they will take increasing amounts of this precious commodity as the iPad and its Androidgenous kin proliferate. People are already feeling the pinch. Re g u l ato r s h ave fe w options to head off the coming bandwidth crisis. They can’t realistically expect to reduce demand. Nor can they expand the overall supply. That leaves the daunting chore ofsqueezing today’s users into narrower slices of the radio spectrum, thereby eking out more space for other things. That’s sometimes possible, but it’s not easy. To reengineer existing radio systems—or their users—is a bit like trying to overhaul a car’s engine while it’s barreling down the highway. Policymakers, at least in private, sometimes hold out hope for a fourth option: that some game-changingtechnical breakthrough will save the day at the 11th hour. But nothing now on the drawing board suggests that technolo alone can get us out of this predicament. In a sense, history is just repeating itself. Two decades ago, people who accessed the Internet typically did so with phone-line modems chugging along at 14.4 kilobits per second. That was fine for the largely static, text-based Internet ofthe day. But as the use of graphics and sound, and then video, expanded, so did the bandwidth needed, prompting more people to obtain broadband Internet con28
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nections. The spread of faster connections in turn spurred Web designers to load up their sites with multimedia. Technolo and content each drove the other. Now we are seeing an equally vicious cycle inthe wireless realm. Smartphones, along with fully mobile laptops and tablets, are spreading fast, and people are using them ever more hours of the day. Estimates show the amounts of such wireless data doubling or tripling annually. We can expect a hundredfold expansion in just a few years.

Where will all the new capacity come from? Addressing this issue demands first an understanding of why allradio spectrum is not created equal.

Every application of radio works
best within a certain range of frequencies, and mobile broadband is no exception. Its sweet spot is relatively narrow, roughly in the range of 300 to 3500 megahertz. That’s because radio waves that are much above 3500 MHz (shorter than about 9 centimeters) do not penetrate well into buildings or through rugged terrain,leading to frustrating dead spots. Lower frequencies are better in this regard, but they require awkwardly large antennas for efficient transmission; 300 MHz is roughly the lowest frequency compatible with a reasonably e cient antenna that’s small enough to fit in a handheld device. Not sur pr isingly, this swath of the spectrum is already staked out in

much of the world. Finding ways that use lessradio bandwidth to carry out these communications is not impossible, but it requires the adoption of some new technologies. Telecommunications regulators try to anticipate such developments, and sometimes they even help to bring them about. But much of their work consists simply of codifying and institutionalizing established ways of doing things, which can interfere with e orts to use the...