PAPR Characteristics Analysis of MC-CDMA System

The multi-carrier CDMA (MC-CDMA) is a multi-carrier CDMA system based on the frequency-domain spreading. In the performance of anti-ISI, it has a distinct advantage over conventional single-carrier CDMA when transmitting high-speed data. However, the MC-CDMA system inherits higher peak-average power ratio (PAPR) problem from the OFDM systems, which will lead to the nonlinear distortion in a high power amplifier (HPA). In this paper, the MC-CDMA system model was studied. Besides, the relationship between the envelope power of MC-CDMA signal and the periodic autocorrelation functions and the periodic cross-correlation functions of the spreading code sequences were analysed. For the PAPR in a 16-user MC-CDMA system, the simulations were given based on the orthogonal Gold code sequences and the Go lay complementary sequences. The simulation results show that when Go lay complementary codes are selected as the spreading codes of MC-CDMA system, the PAPR of the system becomes less. Consequently, the correlations of codes should be emphasized while selecting the spreading code sequences.