Abdo, Mohammed (Prof.)Benyam, Hailegnaw2018-06-252023-11-042018-06-252023-11-042016-08http://etd.aau.edu.et/handle/123456789/3097The underutilization of existing radio spectrum and scarcity of available channel become a challenge for modern era communication system. Services such as high speed data communication requires more bandwidth and wide spectrum range. The rising demand in wireless services and applications bring channel constraint on the existing frequency spectrum allocation scheme. To mitigate such a problem the idea of cognitive radio technique came into picture. Cognitive radio can be defined as a radio system that can adaptively and dynamically allow user(s) to use the spectrum when the primary user is absent. The detection and decisions of the primary signal can be facilitated by spectrum sensing technique. Among those techniques, energy detector spectrum sensing is a transmitter based spectrum sensing technique which detects the presence of primary user in cognitive radio system. Detection of primary signal is made by comparing the received signal energy to that of pre-determined energy threshold value. However the performance indicator matrices show that the energy detector algorithm has poor performance when the received SNR value is too low. This thesis work attempts to analyze and compare the performance of energy detector when adaptive Weiner filter is inserted on the front end of conventional energy detector. Based on the performances matrices value, evaluation of the systems (conventional and enhanced energy detector) response will be done. The performance matrices parameters include: Receiver operating curve (ROC), Complement Receiver Operating Curve (CROC), threshold value vs false alarm probability and Detection probability Vs SNR value. The results are presented for AWGN and Rayleigh flat fading channel model. Accordingly focus is made on how the conventional energy detector behaves when the adaptive Wiener filter is inserted on the front end. Finally simulation results show that, insertion of adaptive Wiener filter in the front end of conventional energy detector has improved all the performance matrices considered in thesis work. Keywords: Cognitive radio, primary user, spectrum sensing, energy detector, performance matrices (receiver operating curve, complementary receiver operating curve, threshold value, false alarm and detection probability), adaptive Weiner filter.enCognitive radioprimary userspectrum sensingenergy detectorperformance matricesreceiver operating curvecomplementary receiver operating curvethreshold valuefalse alarm and detection probabilityadaptive Weiner filterThesis