Contemporary Techniques in Spectrum Sensing and Sharing in Cognitive Radio: A Review

Cognitive Radio (CR) is a promising technology to improve the spectrum utilization efficiency in Wireless Communications. Cognitive means "Relating to the part of mental functions deals with logic". And Cognitive Radio, in which a transceiver can intelligently detect which communication channels are in use and which are not, and instantly move into vacant channels while avoiding occupied ones. Researchers show that more than 70% of available spectrum is not used efficiently. For efficient utilization of spectrum we need to know whether the spectrum is used by primary user or not which is called Spectrum Sensing. Due to the increasing demand for wireless communication CR allows better use of the radio spectrum. CR is intelligent network that adapt to the changes in spectrum environment. The main aspect of the cognitive radio is spectrum sensing. It is one of the most challenging issues in cognitive radio systems. In this paper, a brief overview of cognitive radio, study of spectrum sensing techniques for cognitive radio and spectrum sharing is presented. Various sensing and sharing scheme for the cognitive radio are reviewed and the challenges associated with them.