Cognitive radio (CR) is a kind of wireless communication wherein a transceiver can intelligently sense the vacant and occupied communication channels and promptly move into vacant channels while staving off occupied ones. This enables the optimum use of available Radio-Frequency (RF) spectrum whereas avoiding the interference to other users. Cognitive radio is a key technology that came up with the solution of the problem of underutilization of radio frequency. To explore the capabilities and benefits of CR in better way, researchers now a days are interested in adaptive control paradigms such as fuzzy logic, artificial neural networks, neuro-fuzzy approach etc. The work presented in this book mainly composed of the analysis of available frequency and its allocation to the Secondary Users (SUs) / CRs by using fuzzy logic. A new approach of Spectrum management is introduced in it by resolving the issue regarding the allocation of bandwidth to the appropriate secondary user or the cognitive radio which can use the frequency band for its transmission.