An analytical method of nonlinear distortion in direct sequence spread spectrum multiple access communication systems in baseband

We analyse the effects of the nonlinearity, which resides in a transmission line, on the baseband signal in a direct sequence spread spectrum multiple access (DS-SSMA) communication system, assuming that the nonlinearity is represented by the power series of the input signal. We have studied the dominant part (up to the 3rd order) of the signal distorted by the nonlinear circuit in the line using the Fourier method, and propose an analytical method of the S/N at the output of the correlation detector. We also justify our method by comparing calculated results with the simulated ones in the case when the nonlinear circuit model is expressed by the error function as a typical example.<>