There is a battle going on over control of the spectrum allocated for broadcast of HDTV. The FCC has drawn a line in the sand as to when the switchover will take place – It may yet prove to be a dotted line, but at least it is a line – and the industry is preparing for the wholesale spectrum switch that will result.

One key question is what will happen in unused spectrum in a particular area. There are huge swaths of so-called white spectrum that has been allocated to particular channels but not used in particular vicinities. The technology exists today to build devices that can sniff the airwaves and adjust to use spectrum that is unused, whether that spectrum is licensed or not. These “smart� or “cognitive� radio devices could fill in these gaps quite effectively, and the FCC has released a Notice of Proposed Rulemaking to allow unlicensed devices to use this spectrum as long as they adhere to a set of rules that should prevent interference with licensed use of the spectrum.

This could be a huge advance for unlicensed communications like the 802.11 family, Bluetooth, or any number of other protocols. To date they have had to inhabit the tag-ends of the spectrum, but if these rules come to be there could be an explosion of creative applications with real range and throughput capabilities.

Predictably, the broadcasters are attempting to block this usage. One could speculate on their motives, but the bottom line is that they have thrown up a number of objections based on how much these usages would interfere with their licensed operation.

A group of three major heavyweights have come out with a paper that effectively addresses these objections, as reported in EE Times. This paper is not only technically interesting, but it is also a tutorial on how Powell’s FCC (He is the one that originated this attitude before he left) is taking on the established commercial interests. We can only hope that there is enough backbone still left at the FCC to follow through with initiatives like this.

Larry Mittag