A method of limiting the processing delay of the improved multi-stage variable group hybrid interference cancellation scheme for CDMA systems

The improved variable group hybrid interference cancellation (I-VGHIC) proposed by Ang and Krzymien (see Proc. IEEE Int. Symp. on Personal, Indoor and Mobile Radio Comms., Osaka, Japan, 1999) outperforms both the parallel (PIC) and successive (SIC) interference cancellation in AWGN and flat Rayleigh fading channels. Due to the adaptive nature of the I-VGHIC, its processing delay varies according to the signal power spread of the users seen at the base station. The processing delay of the I-VGHIC is shown to be smaller than that of the SIC when the number of users is large. A method of limiting the I-VGHIC processing delay is proposed. There is no performance loss in the AWGN channel. However, in Rayleigh fading channel, there is a trade off between the BER performance and processing delay