Performance analysis of coherent DS/CDMA systems with antenna diversity in Rayleigh fading channels

We investigate the performance of coherent direct-sequence code division multiple access (DS/CDMA) systems with antenna diversity in Rayleigh fading channels. For a DS/CDMA system operated in fading channels, the multiple access interference (MAI) is affected by fading. We determine the distribution of multiple access interference (MAI) in Rayleigh fading channels. Two simple approximation methods for MAI distribution are proposed, and compared with the exact MAI distribution. Using the exact and approximated MAI distributions, we evaluate the bit error probability (BEP) expression for coherent DS/CDMA systems with antenna diversity. Moreover, the BEP accuracy of the standard Gaussian approximation is investigated as the number of users, processing gain, and the number of antennas are varied.