A predistorter for nonlinear distortion in multi-code CDMA systems

In this paper, we present a predistorter for compensating for nonlinear distortion introduced by high power amplifiers (HPAs) employed in multi-code code division multiple access (CDMA) systems. Since the multi-code CDMA system has the multi-level property in its signal amplitude, the performance of the system is severely degraded by the nonlinear effect of the HPA in the transmitter. In order to mitigate this undesirable distortion, we develop a new data predistorter, which rests upon the fixed point approach associated with the contraction mapping theorem. With utilization of the proposed predistorter, we can significantly improve the performance of the multi-code CDMA system compared to that of the system without the predistorter in terms of bit error rate. Furthermore, since the proposed predistorter employs an iterative method, its implementation is relatively simple.