Thesis (Ph.D.) - Cairo University - Faculty of Engineering- Department of Electronics and Communications

With the increasing demand on wireless communications, the scarcity of the spectrum has become a persistent problem, as the conflict between spectrum supply and demand is increasing. Cognitive Radio (CR) technology is proposed in order to promote the efficient use of the spectrum and revive the lack of spectral resource. The goal of this research is to propose new methods to optimize the performance of CR systems in terms of Receiver Operating Characteristic (ROC). Firstly, novel schemes for spectrum holes sensing for cognitive radio based on the estimation of the Stokes parameters of monochromatic and quasi monochromatic polarized electromagnetic waves are proposed. A closed-form expression for the polarization detection is derived using Ü{u2212}{u03E5} generalized fading model, which in turn provides expressions for the special cases of Nakagami- and Weibull models as well as their derivatives

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