Abstract: The aim of this study is to investigated the performance of the energy detection in Rayleigh fading channel. Only single user detection situation was investigated. To design a communication link that models fading, we simulate the Rayleigh channel using the correlation matching criterion. After that, we check the quality of the transmission, the BER was analyzed for different modulations schemes. We found that BPSK modulation is less affected by errors. The numerical results of the detection are plotted as Pf Vs Pd for different values of SNR on the one hand and on the other hand depending on the number of samples used for the listening of the channel. The results show that the performance of ED depends on the number of samples and the SNR values.