Analysis of Ber Degradation for Transmitted Downlink DSCDMA Signals
A Pre-Distorter-High Power Amplifier (PD-HPA) pair has become a common practice in wireless communication to compensate for nonlinear distortion due to HPA. However, the PD-HPA pair still produces severe signal distortion when the input signal exceeds the PD-HPA's saturation level. The effects of such distortion on Bit Error Rate (BER) degradation in downlink Direct Sequence-Code Division Multiple Access signals (DS-CDMA) are analyzed. The authors establish which signal characteristics at the HPA input and the factors contributing to BER. Assuming that the baseband CDMA signal is characterized as a complex Gaussian process, they develop analytic expressions for the BER and the contributing factors to BER.