Performance of multicode DS/CDMA with noncoherent M-ary orthogonal modulation and successive interference cancellation

An accurate approximation is derived for the bit error rate of uplink multicode direct-sequence code-division multiple-access (DS/CDMA) with noncoherent M-ary modulation in wideband fading channels, when successive interference cancellation is used at the receiver. The receiver noncoherently combines the multipaths via equal-gain combining. The analysis takes into account the effect of error propagation due to incorrect decisions and the fact that all codes of a multicode user fade along the same propagation path. The obtained analytical expression is shown to closely match the Monte Carlo system simulations, especially for a larger number of users.