Performance assessment of MC-CDMA and MC-DS-CDMA in the presence of high power amplifier non-linearities

The combination of code division multiple access (CDMA) and multi-carrier modulation (MCM) (referred to as multi-carrier CDMA) has been proposed as a possible candidate for future generations of wireless/mobile systems. Much work has been done on the performance of such schemes in various environments, with different channel models, predominantly assuming linear channels. Accordingly, in this paper we explore the influence of the effects of non-linearities (introduced by the transmitter high power amplifier (HPA)) on multi-carrier CDMA systems using higher order modulation schemes. We consider two techniques for combining CDMA with MCM: multi-carrier CDMA (MC-CDMA) and multi-carrier direct sequence CDMA (MC-DS-CDMA) and analyse their performance in the presence of an HPA and additive white Gaussian noise (AWGN), paying particular attention to the total degradation and the spectral spreading.