Spectrum Access and sharing is mainly focused on utilizing the unused spectrum of licensed users, without interference and enlarge the spectrum usage. The frequency spectrum is selected to operate at a given location, at a given period of time to optimize the use of idle spectrum and deny interference with other radios or other system are said to be DSA. CRN focuses majorly towards primary users and this concept is accepted in DSA as the primary users are to be protected, by maximizing the performance of secondary users, considering the metrics of false alarm and missed detection. In order to face the requirements of the probability of missed detection, traditional spectrum sensing techniques can unnecessarily increase the probability of false alarm with opportunistic reuse of spectrum by lowering the ability to influence the spectrum hole. The probability of interference and the new metric of spectrum sensing consider solving this interference and missed detection. In this the secondary users pay to the primary users while accessing the band temporarily.