SER performance of linear multiuser detectors for DS-CDMA downlink with transmitter nonlinear distortions

The aim of this paper is to examine the effects of the nonlinear distortions introduced by the high-power amplifier in the downlink of direct-sequence code-division multiple-access systems. By modeling the nonlinear distortion effects as a signal power loss and a superimposed colored Gaussian noise, we derive the symbol-error rate (SER) of the minimum mean-squared error (mmse) detector in additive white Gaussian noise channels. Successively, we make use of a semianalytical approach to obtain the SER performance of linear multiuser detectors, such as the RAKE, decorrelator, and mmse receiver, in frequency-selective fading channels. Simulation results confirm the effectiveness of the theoretical approach. Index Terms--Direct-sequence code-division multiple-access (DS-CDMA), downlink, multiuser detectors, nonlinear distortions.