Analysis of non-linear distortions on MC-CDMA

We analyze the influence of the effects of the non-linearity due to high power amplifiers in MC-CDMA scheme using BPSK modulation. The results are compared to those obtained with the classical BPSK modulated DS-CDMA scheme. It is shown that without predistortion the total degradation for the up-link of a cellular mobile communications system is about 2 dB more for the MC-CDMA system compared to the DS-CDMA system. However, for the down-link case (assuming a full system load) the MC-CDMA system outperforms by about 1.5 dB the DS-CDMA system. In addition, the performance of an analytical predistortion technique is evaluated. The results with predistortion showed that for the up-link of a MC-CDMA system one can achieve about 1.8 dB gain. Similar gains for the down-link case are also obtained. Hence, with predistortion, the HPA non-linearities may have the same influence on the performance of the up-link of both systems, i.e. MC-CDMA and DS-CDMA systems