Bit-Error Probability of Asynchronous Multicode DS-CDMA Systems in Rayleigh Fading

摘要

A precise bit-error probability analysis method for multicode DS-CDMA systems in Rayleigh fading is derived. The proposed method applies to a multicode DS-CDMA system with an arbitrary number of multiple code sequences and any selection of multiple code sequences. The method gives accurate results for Rayleigh fading while requiring only a single numerical integration of an integrand involving the well-known Q-function. The solution discriminates the effect of the selection of different multiple code sequences on the bit-error probability, whereas Gaussian approximations do not. Numerical examples show that the differences between exact and approximate methods for a multicode DS-CDMA system operating over Rayleigh fading channels may be more significant than for a single code system in Rayleigh fading channels or for a multicode system in AWGN channels when the spreading factor is not significantly large compared to the number of multiple code sequences.