The need for the spectrum access is increasing day by day as the users are developing more interest for the utilization of the spectrum technique. But as a design issue the range of the spectrum cannot be enhanced with the need of the users and area. Hence the researchers have found the path of direction in the ideal strategy of the usage of secondary users for the spectrum in the absence of the primary users. Hence in this process, a new technique has been raised termed as the spectrum sensing for the identity of primary users with plenty of techniques and technologies, one of device used for the process of identification is the Cognitive Radio. The sensing of the spectrum criteria also involves the gathering of the signal features from the spectrum with its threshold optimized depending on the received values. Upon the detection of the threshold values the spectrum can sense the presence of the user as primary or not. The techniques that are involved in spectrum sensing are energy detection, matched filtering, correlation, etc.