An iterative multi-user decoder with soft-interference cancellation

Two multi-user soft-interference cancellation algorithms are presented for synchronous narrow-hand BPSK users. The two techniques are designed for multiple user detection where the users use highly correlated waveforms for modulation. The techniques perform close to the optimal cross-entropy multi-user decoder on the K-symmetric channel for cross-correlations up to 0.5. For higher cross-correlations on this channel, we introduce an initial decorrelation step prior to the first iteration, which greatly improves the performance for the high values of cross-correlation. The complexity per bit per iteration increases linearly for the two interference cancellation algorithms rather than exponentially as for the cross-entropy decoder.