Open Spectrum

David Weinberger, David Reed, and others are on a kick to deregulate the airwaves in order to achieve greater democracy, invite the audience into the conversation, and save the world. One of the ideas in Framing Open Spectrum is on the border of rationality, although it’s awfully hard to tease it out of the rat’s nest of 60s idealism in which it’s housed: frequency-agile digital radios are capable of selecting clean portions of local spectrum, and don’t need quite all of the old-fashioned single use management that’s been the FCC’s business for lo these many years. There are still practical limits to frequency-hunting, however, and most of them have to do with the time it takes to discover clean spectrum, the responsiveness of agile radios to occasional interference, and the different needs of infrastructure devices (access points) and mobile devices.

I wouldn’t shut down the FCC just yet, but there is an argument to be made for more flexible spectrum policies, and the FCC is already on to it.

But at the same time, the ability of smart radios to recognize sources of interference and route around them to different frequencies isn’t as robust in contemporary systems such as WiFi as it needs to be in order for self-managed spectrum to work, with or without the FCC. Here’s a trivial example: A WiFi mobile system can only use the frequency selected by its Access Point. But it may find itself in a position where it can see two Access Points operating at the same frequency who can’t see each other because they’re too far apart (but the mobile node is in the middle, where the signals overlap). WiFi doesn’t provide a hook for the mobile node to tell its Access Point to shift to a different channel because of the interference it sees. So the system has a problem.

It’s a solvable problem, but not by the control procedures invented to deal with the environment assumed by WiFi’s designers when the standards were created. And if WiFi needs enhancement to work in a smart radio environment, what do you suppose has to be done to all the other RF protocols that are even more rudimentary than WiFi?

Right, we’re not there yet.

Link via Dan Gillmor.