Monday, July 31, 2006

Mental models for wireless spectrum

Technologist David Reed once said, “There's no scarcity of spectrum any more than there's a scarcity of the color green." [1] This quip presumes the technically correct meaning of spectrum as a range of vibration frequencies of electromagnetic waves. However, it’s clear that when most people talk about spectrum, they don’t mean a vibration frequency. What do they mean?

I've been working through examples of how lay people conceive of spectrum, and talk about spectrum policy. An early draft (Word doc; source data in spreadsheet form) explains why some policies and proposals make sense to us, and other things don’t. I’m not making claims about how experts think, though I suspect that the metaphors I’ll describe is at the root of their thinking, too.

In summary, spectrum is conceived of as a spatial resource, with two common variants: spectrum as a set of containers (bands), and spectrum as land. There are two common mental models of wireless signals: as objects moving through space, and as sounds, particularly speech. This leads to two mental models for interference, which entail conflicting, and sometimes incorrect, deductions.

Spectrum, as the concept is treated by regulators and politicians, is a resource used for communication which is, in the first instance, under state control. Its assignment is thus the stuff of politics, that is, arguments over the distribution of scarce resources. The spectrum-as-land model is “natural” to most people because the underlying spatial metaphor, of real estate in particular, fits our notion of land resources.

The results of this analysis can be used to identify policy-making pitfalls. For example, Hatfield & Weiser [2] explain why the transition to a property rights model for spectrum is far more complex than commonly portrayed; this work hopes to explain why a model of real property rights is attractive in the first place.


[1] Quoted by David Weinberger in The myth of interference, Salon 12 March 2003. Curiously, if one considers electromagnetic radiation in optical fiber, there is indeed “a scarcity of the color green” because each fiber supports a finite number of wavelengths. For example, links in the National LambdaRail network use dense wavelength-division multiplexing (DWDM), which allows up to 32 or 40 individual optical wavelengths to be used (depending on hardware configuration at each end). Once those wavelengths are occupied, no more are available.

[2] Hatfield, Dale N and Philip J Weiser (2006), “Property Rights in Spectrum: Taking the Next Step,” University of Colorado Law School, Paper Number 06-20, June 2006,

Sunday, July 16, 2006

Ted’s Tubes and Larry’s Lanes

The digerati are having a good snigger at Ted Stevens, Chairman of the US Senate committee that’s deciding how the Internet will be regulated. The Daily Show recently lampooned (video clip) his attempts at explaining network neutrality. Senator Stevens said, to much derisive merriment among the net-savvy studio audience:
“The Internet is not something that you just dump something on. It’s not a big truck. It’s, it’s a series of tubes. [...] And if you don’t understand that those tubes can be filled, and if they’re filled when you put your message in it, it gets in line, it’s gonna be delayed by anyone who puts in that tube enormous amounts of material, enormous amounts of material.”

It was amusing because homespun analogies seem out of place coming from a person deciding our high tech future. Ted got a bad rap, though, because no-one can avoid this kind of language. Cognitive science suggests that we have no choice but to use mental models based on the tangible world to reason about intangible things like interpersonal relationships (“we’ve been close for years, but we’re drifting apart”), mathematical abstractions (“the real numbers are points on a line”), and the Internet.

Everyone in this debate misuses metaphor, including Larry Lessig, the house theoretician for network neutrality. An op-ed he wrote for the Washington Post last month with Robert McChesney was premised on an extend (and well-worn) metaphor: The Internet-as-Highway. Some excerpts:

“Congress [will decide whether cable and phone companies] can put toll booths at every on-ramp and exit on the information superhighway. [...] Net neutrality means simply that all like Internet content must be treated alike and move at the same speed over the network. [... Those companies] would be able to sell access to the express lane to deep-pocketed corporations and relegate everyone else to the digital equivalent of a winding dirt road.”

Sen. Stevens uses the Internet-as-Pipes metaphor, and Prof. Lessig prefers Internet-as-Roads. There’s little to choose between them. Both convey some truth, and both have shortcomings.

The superhighway metaphor is inaccurate in that the networks making up the Internet are owned by private agents, whereas most of the highway network is owned by the state. The notion of “speed” is also technically inaccurate: all packets on the Internet move the same speed (some fraction of the speed of light). More packets get through per second on some parts of the network, but because “there are more parallel lanes” rather than because they speed along faster. The Highway metaphor also implies that two distinct Internets will be created side-by-side (echoes of Separate But (Un)equal) , whereas in fact all traffic will move over the same infrastructure, but be prioritized differently.

The choice of analogy has consequences, though. One could mangle poor McLuhan again by saying that the Metaphor is the Message. We think of the highways as a public good, provided by the state for the benefit of all, where everyone is entitled to equal access. This resonates with those on the Left, like Prof. Lessig. The ownership of tubes and pipes varies, but is open to notions of private property and investment, which is agreeable to those on the Right, like Sen. Stevens. Plumbing is invisible, and can safely be left to experts to worry about, whereas roads are something we all feel we have a daily stake in.

The highway metaphor is the more common one in the debate to date. It is perhaps more intelligible; we have more experience with roads than plumbing. However, one shouldn’t forget that it was forged during the last rewrite of the telecom act, which happened during a Democratic administration. I wouldn’t be surprised to see the Right experimenting with alternative metaphors which are better at connoting their values and agenda – plumbing, perhaps, or airlines.

Wednesday, July 12, 2006

Follow the clicks

Spyware is the current BusinessWeek cover story, The Plot to Hijack Your Computer. The technology is now officially mainstream.

Spyware, or “adware” in the terminology of its proponents, figures out our preferences by tracking what we do on the web, and then presents us with tailored pop-up ads. It got a bad name because the software often installs without a user knowing about it, monitors user behavior and relays it back to base, and sometimes disables PCs in the course of trying to disable competing spyware programs.

However, spyware/adware part of the future personal computing because it’s a way to make the dream of “ad supported software” come true. BusinessWeek reports that a company with access to 10 million computers can make about $100,000 a day; that’s 1c/day/computer, or $3/year. According to Om Malik writing for Business 2.0 magazine, Google makes around $16 per user per year in advertising; another $3 would be a 30% increase.

Spyware will be tamed over the next few years, and its technologies incorporated into Yahooglesoft products. If Yahoo, Google and Microsoft were as savvy about regulatory politics as the phone companies, they’d be in Washington DC and Brussels right now trying to craft safe harbor regulations which would allow them to take this technology into the mainstream while marginalizing the cowboys. And consumers will probably lap it up: they don’t like being spied on, but they don’t like paying for stuff even more strongly.