ABSTRACT
Chapter 2 introduces the concept of cognitive radio (CR) and its different elements. Spectrum sensing is one of the primary enabling technology of CR. Spectrum sensing is defined, and a classification of spectrum sensing is given in this chapter. Spectrum sensing is mainly classified into narrowband and wideband spectrum sensing. The cooperative spectrum sensing, where multiple cooperating secondary users collaborate for sensing the spectrum, is also discussed. Spectrum sensing is a classification task where CR users need to classify between the ON and OFF status of licensed users. Machine learning (ML) algorithms are found to perform excellently in classification tasks, and hence ML is being explored for spectrum sensing applications. Each spectrum sensing scheme is discussed briefly, along with the basic building block in this chapter.
