JWCN_V4_N3_A1 Maninder Kaur Journal On Wireless Communication Networks 2320 - 2351 4 3 1 7 Cognitive Radio, Software Defined Radio, SpectrumManagement, Physical Layer, Link Layer Radio Communication Networks rely on the radio frequency spectra which are the set of frequencies ranging from3 KHz to 300 GHz. With increasing demand for wireless communication, this radio frequency spectra has become an expensive commodity. Thus, the efficient use the spectrum resources have become an essential issue. The alternative to inefficient fixed spectrum allocation is the sharing of the spectra amongst the licensed and unlicensed users. Cognitive radio, which is a form of wireless communication is the key technology which provides the best solution by allowing a group of secondary users to share the radio spectrum originally allocated to the primary users. This sharing of the spectrum is termed as Dynamic Spectrum Access (DSA) or Dynamic Spectrum Allocation. The major components of the DSA are the spectrum sensing, spectrum decision, spectrum sharing and spectrum mobility.Management of these tasks collectively is termed as spectrum management. These tasks are handled with the assistance of different layers of the OSI model namely, physical layer, link layer, network layer, transport layer and application layer. This paper reviews the role of different layers of the OSI model in the working of a cognitive radio leading to spectrum management. October - December 2015 Copyright © 2015 i-manager publications. All rights reserved. i-manager Publications http://www.imanagerpublications.com/Article.aspx?ArticleId=4844