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Cognitive Radio and Dynamic Spectrum Access Swati Dwivedi and Alkesh Agrawal Faculty of Electronics and Communication Engineering Institute of Technology Shri Ramswaroop Memorial University Lucknow, India Emails: [email protected], [email protected] Abstract: The mobile sector continues to see dramatic growth around the world. Usage of cell phones, smartphones, and tablets is increasing at a rapid pace. With the growing popularity and ease of use of mobile devices such as iPhone, Android phones, tablets, and other portable devices, new mobile applications are coming online that increase access and capability, particularly in areas such as education, health care, transportation, and commerce. But the tremendous increase in wireless utilization is coming up against the utilization of radio spectrum availability. Cognitive networks are motivated by the lack of spectrum under the current spectrum management policies. Most of the frequency bands useful to wireless communication have already been licensed to the primary users. Recent measurements have shown that for as much as 90% of the time, large portions of the licensed bands remain unused. As licensed bands were difficult to reclaim and release, dynamic and secondary spectrum licensing was considered as an alternative to reduce the amount of unused spectrum. Cognitive radio (CR) is a cooperative communication technology for supporting dynamic spectrum access: Cognitive radio (also called smart radio) can, intelligently detect which communication channels (spectrum) are in use and which are not, and avoid occupied channels and instantly move into vacant ones by using dynamic spectrum access. It allows us to make use of the notbeing-used part of spectrum and thus optimizes the use of available spectrum while minimizing interference to other users by its spectrum sensing method. Keywords: cognitive radio, dynamic spectrum, spectrum sensing