Non è un testo divulgativo, specie quando si entra nel contesto delle ontologie, ma finora non ho trovato niente di così esaustivo come prima introduzione sull'argomento. Questo è il "problem statement" che precede la successiva discussione:
It is well known that radio spectrum (~30MHz ... 30GHz) is inefficiently used, because of our complicated radio regulation. Cognitive radios attempt to overcome this problem. Often, "agile radio" is used as synonym for "cognitive radio." Cognitive radio is not only a new radio technology, it also includes a revolutionary change in how the radio spectrum is regulated.
Today, access to radio spectrum is frustratingly difﬁcult. The access is restricted by an old radio regulatory regime that emerged over the last 100 years. Large parts of our radio spectrum are allocated to licensed radio services, in a way that is referred to as command-and-control. Open access to most of the radio spectrum is only permitted with very low transmission powers, in a so-called underlay sharing approach, as for example used by Ultra Wideband (UWB). The overlay sharing approach, i.e. the free access to open spectrum, is generally not permitted.
Only some small fractions of the radio spectrum, the unlicensed frequency bands, are more or less openly available. Unlicensed frequency bands build a tiny fraction of the entire radio spectrum, where overlay sharing is commonly used. Excitingly, over the past decades, this lead to a wide variety of new wireless technologies and services, among many others the popular Wireless Local Area Network (LAN) IEEE 802.11 and Bluetooth for Wireless Personal Area Network (PAN).
However, spectrum access remains to be a restricting bottleneck that may even slow down the development of new radio services that can substantially improve our health, safety, work environment, education of people, and quality of leisure time.
Changing the status of licensed radio spectrum can be perilous and painfully slow. It takes a concerted effort among government regulatory agencies, technology developers, and service providers to achieve efficient and timely deployment. This is one of the reasons why, paradoxically, 90-95% of the licensed radio spectrum is not in use at any location at any given time. The existing radio regulatory regime is simply too complex to handle the increasingly dynamic nature of emerging wireless applications. As a result, we waste precious spectrum.