Fuzzy adaptive parallel interference cancellation and vector channel prediction for CDMA in fading channels

We propose a fuzzy PIC multiuser detection/vector channel prediction scheme in Rayleigh fading channels. The vector channel prediction is based on the first-order auto-regressive model and the expectation-maximization algorithm. The signal-to-interference ratio and signal-to-noise ratio are estimated from the vector channel model´s parameters, and we adapt the weight of each interference cancellation path via fuzzy inference mechanism. The proposed fuzzy PIC and vector channel prediction cooperate in a way that fuzzy PIC´ some input parameters come from the channel predictor and fuzzy PIC makes the channel predictor more accurate at the next stage. Computing weights via the fuzzy adaptive method adds insignificant complexity because it involves only table lookup. The overall complexity is still linear in the number of users. The simulation results show that the proposed fuzzy PIC/vector channel prediction scheme performs better than previous improved PIC schemes in Rayleigh fading channels