Abstract: One of the fundamental problems for the future wireless systems is where to find suitable spectrum bands to fulfil the demand of future services. While basically all of the radio spectrum is allocated to different services, applications and users, observation provide proof that utilization of the spectrum is actually quite low. In order to overcome this problem and enhance the spectrum utilization, cognitive radio concept has been proposed, an application with this radio is spectrum sensing which is the biggest issue that can detect the spectrum holes or detects the presence of primary users. Cognitive radios works on dynamic spectrum allocation method where any spectrum hole detected by spectrum sensing is then allocated to the secondary user without interfering the primary users. This paper gives a summary of spectrum sensing techniques and dynamic spectrum allocation methods.

Keywords: Cognitive Radio, Spectrum Sensing, Dynamic Spectrum allocation, Primary user, Secondary user.