I just found out about a wonderful explanation of open spectrum that Tim Shepard submitted to the FCC in 2002. When I explain what's possible in open spectrum I typically make analogies to human vision in the presence of sunlight. Tim's explanation is in terms of sound and human hearing, in a football stadium!
What is Open Spectrum?
Every national government regulates the use of wireless spectrum - a result of interference problems that arose in the early decades of the 20th century. Since then, there's been enormous progress in wireless technology. Unfortunately we prohibit the use of this new technology in almost all of the spectrum. This has enormous cost for society. Consider where would our economy be if computers only used technology which existed in 1953 (the year current US color TV broadcasting standards were frozen)? Consider, under current regulations, most wireless spectrum is effectively empty most of the time, even in major cities like New York, London, Tokyo or Beijing.
Today, it's possible to design robust wireless systems that would function reliably even if there were no spectrum regulations at all. Unfortunately, currently deployed wireless systems (radio, TV, navigation, etc.) depend upon current regulations for their reliable operation so, as Tim Shepard puts it, "The path into the future will be tricky."
None-the-less, we owe it to ourselves to navigate that tricky path. If nothing else, we need spectrum to provide "broadband" in rural areas around the world, and to provide high capacity mobile connectivity in both urban and rural areas.