Performance analysis of an improved multi-carrier CDMA system under frequency-selective Rayleigh fading channels

In this article, an analytical method is proposed to study an improved orthogonal multi-carrier DS/CDMA system, which uses QPSK for both spreading and carrier modulations without redundant sub-carriers and time interleavers in each sub-channel. The article concerns in particular such a system and its performance under frequency-selective Rayleigh fading channels with various delay-power profiles. The bit error probabilities under varying multipath-diversity orders (using maximal ratio combing RAKE reception) and different numbers of resolvable multipaths are derived. It has been shown that the system, despite of its structural simplicity, performs well in mitigating frequency-selective fading. The performance is also evaluated taking into account various other parameter sets, such as numbers of users and sub-carriers, lengths of PN codes and the number of fingers in an RAKE receiver, etc.