ABSTRACT
This chapter provides the basic concepts of cognitive radio networks (CRNs). They are cognitive cycle, functions of the Cognitive radio (CR) framework and the paradigms of CR access. The CR framework is based on interactions among different entities within the network as well as with the surrounding environment. The CR paradigms can be classified into three main categories: interweave, underlay, and overlay paradigms. The main feature of the CR paradigm is dynamic spectrum access, as opposed to conventional wireless paradigms, which abide by a static spectrum allocation policy. A typical CR transceiver consists of two key elements: the radio front end and the baseband processing unit. A comprehensive spectrum management process consists of four major elements: Spectrum sensing and awareness, Spectrum decision, Spectrum sharing and Spectrum mobility. Each component of the spectrum management process must coordinate with the other components. The chapter also presents an overview of the key concepts discussed in the subsequent chapters of this book.
