Date Added: Jan 2011
In this paper one of the most important cognitive radio task i.e. spectrum sensing is explained in detail. Cognitive radio is an intelligent wireless communication technology in order to increase the spectrum efficiency. Increasing efficiency of the spectrum usage is an urgent need as an intrinsic result of the increasing demand for higher data rates, better quality of services and higher capacity. There are several spectrum sensing techniques proposed in literature for cognitive radio based systems like Non cooperative and cooperative spectrum sensing. But there are some practical challenges and limitations in these techniques.