Spectrum is scarce
USS Clueless wrote up a good article talking about how CDMA cellular technology squeezes more data into less radio spectrum through "spectrum sharing". Spectrum sharing (forcing processors to clean up noisy signals) is one of the key technologies open spectrum advocates invoke when arguing that all spectrum should be unregulated. I've long been skeptical of these assertions, so I asked Steve Den Beste if spectrum sharing technology can, indeed, make spectrum non scarce. He answered:
No.To do: bone up on Shannon.
Spectrum usage is subject to Shannon's work. Spectrum is a finite resource and if too many people try to use the same spectrum then no one gets anything out of it.
Technology can't fix this. It's inevitable because of the laws of physics.
Shannon's work is in part based on the Second law of Thermodynamics.