The case is being made for opening the premium spectrum used by broadcasters in an article in The Economist and Shirky's Writings. The focus is on interference which previously required geographic monopolies managed by regulators, but we and our radios have gotten smarter since then. If we can get past the issue of interference, it means more than returning a public trust to a public commons, it unleashes innovation in areas we have just begun to explore.
The sheer waste of this system—the “opportunity cost” of services and technologies not offered because entrenched interests are squatting on the spectrum—is behind the third major intellectual current, after central planning and property rights, in recent thinking about spectrum. Starting in the 1980s and gathering steam in the 1990s, there have been calls for “open spectrum”, or a spectrum commons. These initially met with scepticism, since economists and most other people are familiar with “the tragedy of the commons”—the idea that a scarce resource will be inefficiently over-exploited (as in the case of over-fishing, the classic instance). For sceptics, the same fate would await the airwaves.But this is wrong, says Kevin Werbach at the University of Pennsylvania's Wharton business school and founder of Supernova Group, a consultancy. He argues that the assumption that public sharing of spectrum would lead to chaos presumes that spectrum is scarce; but this reflects a flawed understanding of the physics of electromagnetism. A common myth about electromagnetic waves is that they bounce off one another if they meet. They do not. Instead, they travel onwards through other waves forever (even though they eventually attenuate to the point where they become undetectable). Radio interference, in other words, is not a physical phenomenon, but always and only a technological problem, the result of dumb radios and dumb antennae mixing the waves up after receiving them.
Of course, spectrum owners disagree:
“Unlicensed spectrum is sounding like crack cocaine: the ultimate high that solves all your problems,” says Brian Fontes, a lobbyist who works for Cingular, America's second-largest mobile-phone company (and the largest once its acquisition of AT&T Wireless, a rival, is complete). But, “prove that you're not going to interfere; I mean prove it, don't just say it,” he insists.
Clay provides proof:
Unlike the 2.4 Ghz band, which was already used by microwave ovens and other appliances, the broadcaster's spectrum is only used for communications, so they will have to be shown that new devices can not only cooperate with one another, but operate without disrupting current signals. (The prospects for this are good -- in a related test in February concerning low-power radio, the company performing the interference tests concluded, "Due to the lack of measurable interference produced by [low-power] stations during testing, the listener tests and economic analysis scheduled for Phase II of the LPFM field tests and experimental program should not be done." Report in PDF.)
Setting interference aside, if not putting the issue to bed, enables us to focus on the opportunities of distance with yet to be deregulated bands of spectrum. Clay points out physical constraints and the value of some monopolized bands:
Like the diminishing height of waves that emanate outward from a rock dropped in a pond, the power of a wave radiating outward from a broadcasting antenna falls as the distance from the antenna increases. Worse, this falloff isn't just related to distance, it is the square of that distance. This pattern, called the inverse square law, says that power at distance N will be 1/N2 -- two miles from a given broadcaster, the signal will be 1/4th the strength of the signal at one mile, at three miles, it will be 1/9th, and so on....Because of the tradeoff between penetration and data rate, most of the useful radio frequencies are in the kilohertz (Khz) to Gigahertz (Ghz) range -- low enough to travel through walls, high enough to carry the data required for voice or video signals.
Nobody anticipated the level innovation that has occured with the scrap of spectrum left over for Wifi. Based on the success they have had, some even suggest that its enough: Dewayne Hendricks, boss of Dandin Group, a wireless internet-access provider, does not care whether governments open up more spectrum because, “all the spectrum we need is already in play.”
But wireless will not realize the death of distance until more useful radio frequencies are opened. The lower hanging fruit is providing services behind walls or across cornfields. But much prophesized decentralized architectures such as mesh networks also require new spectrum to play with.
I have long held that mesh networking with current architectures is crippled by economies of span. That is, each time a node intermediates in a path it introduces latency, a transaction cost that adds up quickly in mesh architecture. A digital signal is slowed down when processed. In a mesh, this cost is somewhat offset with the risk benefits of additional redundancy. But an optimal mesh uses a few intermediate nodes as possible. A structure less like a filter and more like a network.
The latent potential of open spectrum has yet to be realized, because innovation banned from frequencies with low latency in implementation. If we can get past issues of interference, benefit from new allocations and get down to building new architectures, there is ample room for innovation.
