SC/FDE, OFDM and CDMA: A Simplified Approach

We apply code division multiple access CDMA to single carrier transmission with frequency domain equalization SCFDE. We use the Fourier spreading codes at the transmitter with length equal the number of users and across the active users. It leads to the cancellation of the despreading process together with the inverse fast Fourier transformation (IFFT) at the receiver, and hence, we get the performance of SCFDE-CDMA with less complexity. Nevertheless, the system is transformed to OFDM. We obtain multicarrier OFDM, by applying IFFT across an arbitrary parallel SCFDE CDMA signals. The behaviour of the peak to average power ratio PAPR of the output signal reveals Gaussian distribution, and thus, the PAPR is improved. It is therefore adequate to and effective in the nonlinear region of the power amplifier