Using information theory to more fully exploit the electromagnetic spectrum: lessons for regulators

This paper takes tools arising from information theory, used to analyze modulation and coding trade-offs in digital system design, and extends them to the regulation of the electromagnetic spectrum. The benefits to existing spectrum users under the regulatory regime of technical flexibility are demonstrated in the use of the bandwidth-efficiency plane, which shows that extra communications capabilities can be created without sacrificing competitive system performance, if extra communications resources of power or bandwidth are available. Other regulatory policies that encourage spectrum leasing and facilitate secondary markets would permit licensees to take these extra communications capabilities more directly to the marketplace. In addition, it is demonstrated that the imposition of a requirement external to the goals of system design-e.g., operating at a noise level other than that of the original design-would appear to be a "tax" on either the performance of the system or the communications resources themselves. Regulatory decisions have been made that permit increased licensed and unlicensed access based on findings that, while such a "tax" exists for particular circumstances, it is minimal and its impact, "acceptable."