with the introduction of new standards at a fast pace, wireless communication is experiencing great development and growth, thereby raising the level of demand for radio spectrum. The spectrum, however, is a limited resource and cannot be subdivided indefinitely to satisfy any use. As a result, spectrum scarcity arises. This scarcity represents the main problem that faces the future of wireless networks. This scarcity is due to the inefficient fixed spectrum allocation technique. The Dynamic

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... ctrum Access (DSA) is a successful solution to reduce the spectrum scarcity that wireless communications currently face. DSA allows users without a spectrum license known as Secondary Users (SUs) to temporarily use the unused licensed spectrum. This work focuses on analysis, and design of the Cognitive Radio (CR) system forOrthogonal Frequency Division Multiplexing modulation. The OFDM transceiver system has been implemented in the first stage using the Quadrature Phase Shift Keying (QPSK) modulation technique by Xilinx System Generator Inter-Symbol InterferenceSimulink (XSG) based on MATLAB. The second stage of the proposed system is to design energy detection of the OFDM transceiver. This system was analyzed under the Adaptive White Gaussian Noise (AWGN) channel based XSG. In this work, the energy detector is also designed using the XSG ISE14.1 Simulink and obtained all the signals successfully. Index Terms— CR, Spectrum Sensing, OFDM, QPSK, ED, AWGN.