Performance of multi-code CDMA in a multipath fading channel

The authors provide a general investigation on the performance of multi-code code division multiple access (MC-CDMA) over Rayleigh fading plus additive white Gaussian noise (AWGN) channels. In MC-CDMA, high speed data sources are serial-to-parallel converted to low speed streams, which are further spread by Hadamard-Walsh orthogonal sequences and random codes. Numerical results show that, in a multipath fading channel, MC-CDMA with properly assigned Hadamard-Walsh sequences outperforms conventional CDMA when the signal to noise ratio (SNR) is low and shows comparable performance at high SNR. Furthermore, for the AWGN channel, the approximate formula developed by Lee et al. (see Proceedings of IEEE PIMRC´97, San Diego, p. 297-301, 1997) shows more variation than the authors´ formula. The new approach is capable of telling the impact of code cross-correlation on system performance while the earlier approach does not