Cognitive Radio Implementation Issues in Channel Sensing

Cognition means state and contextual awareness, reasoning and conclusion formulation, and a method by which application can be re-configured. Cognitive Radio (CR) is one such Intelligent Wireless Communication system that is built on Software Defined Radio which collects information from the surrounding environment and uses this learning to adapt itself to the variation in the input stimuli [7]. The major objective of a Cognition based Radio is to deliver highly reliable communication as well as highly efficient utilization of the most precious natural resource of wireless communication, the frequency spectrum. Usually spectrum access is a significant problem than the physical scarcity of the spectrum. This is due to the command and control regulations that limit the access to potential spectrum. Cognitive Radio is a measure proposed to support the efficient utilization of the frequency spectrum by making the most of the spectral gaps or unused spectrum holes. Various cognitive methods are being investigated to reuse the locally unused spectrum to increase the total system capacity. Identifying the free unused spectrum is the first step in cognition that provides opportunistic access of the spectrum by the secondary (unlicensed) users [14]. Channel sensing forms an integral part of Cognition that selects the channel, utilizes it and finally implements it. The initial sensing of the channels and the final implementation and application of end user raises many issues in Cognitive Radio Systems. Liberating the spectrum would materialize better and optimized connectivity and would enable new