Dynamic Spectrum Access (DSA) in Wireless Cognitive Radio Networks (WCRN)

Dynamic Spectrum Access (DSA) is a technology that senses the unused ‘free' but allocated portion of the radio frequency spectrum on a non-interfering basis. These unused bands are also known as ‘holes' or ‘white spaces'. DSA also refers to the time-varying, flexible usage of parts of the radio spectrum under consideration of regulatory and technical restrictions. This type of spectrum access is due to the dynamic behavior that the Secondary User (SU) must employ in order to access the spectrum, while avoiding interfering with a Primary User (PU). Intelligent or Cognitive Radio (CR) is a platform on which the DSA can be implemented. CRs are radio systems that autonomously coordinate the usage of spectrum. They utilize radio spectrum when it is not being used by incumbent (primary) radio systems. Underutilized spectrum can be exploited with the concepts of DSA and CR. This paper reviews the techniques that can be deployed for DSA reliably in a Wireless Cognitive Radio Network (WCRN) and models of network architecture-based DSA in Cognitive Radio Networks (CRN)