Cognitive Radio (CR) was introduced by Mitola in [1], in order to improve the distribution of the frequencyspectrum to satisfy the growing evolution in wireless applications. Therefore, the major goal of CR is toidentify the non-presence of Primary User (PU) which has the legal right of transmission [1] [2]. In case ofabsence of PU, the CR can allocate the unused band to a Secondary User (SU). The SU should stop histransmission if PU starts to be active, in order to avoid any interference. In fact, many techniques have beenintroduced in order to estimate the opportunity of free bandwidth; those techniques could be classified as:Blind and Cooperative. The cooperative techniques need a priori information about the PU to do the sensingof the channel, while the blind techniques do not.