Iterative Frequency-Domain Soft Interference Cancellation for Multicode DS- and MC-CDMA Transmissions and Performance Comparison

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can significantly improve the BER performance of DSand MC-CDMA systems in a severe frequencyselective fading channel. However, since the frequency-distorted signal cannot be completely equalized, the residual inter-code interference (ICI) limits the BER performance improvement. 4G systems must support much higher variable rate data services. Orthogonal multicode transmission technique has flexibility in offering variable rate services. However, the BER performance degrades as the number of parallel codes increases. In this paper, we propose an iterative frequency-domain soft interference cancellation (IFDSIC) scheme for multicode DSand MC-CDMA systems and their achievable BER performances are evaluated by computer simulation. key words: DS-CDMA, MC-CDMA, frequency-domain equalization (FDE), multicode, interference cancelation