Date Added: Apr 2012
There have been significant advancements towards realizations of cognitive radios, as well as towards the development of the various enabling technologies needed for the diverse potential application scenarios of CRs. Nevertheless, the authors have also seen that a lot of further research and development work is definitely needed before general cognitive wireless networks can be realized. Cognitive Radios (CRs) can exploit vacancies in licensed frequency bands to self-organize in opportunistic spectrum networks. Such networks, henceforth referred to as Cognitive Radio Networks (CRNs), operate over a dynamic bandwidth in both time and space. This inherently leads to the partition of the network into clusters depending on the spatial variation of the Primary Radio Network (PRN) activity.