Cognitive Radio System: Overview of Research Challenge

software defined radio, defined by IEEE as 802.22 aimed at using cognitive radio (CR) techniques to allow sharing of unused spectrum as it is aware of wireless environment, its internal state policies. It automatically and dynamically adapt its self from the surroundings and learn from its past experience. Based on software-defined radio, it provides flexibility and also offers much more efficiency for the overall usage of the radio spectrum[1]. CRS has been emerging as a key technology targeted at providing very high spectral efficiency. In this paper we present an overview and challenges of spectrum management for CRS