Iterative multiuser detection with soft feedback with a subsequent stage utilizing Hopfield networks for error search and correction

In this paper, a second stage for algorithms applying iterative soft decision interference cancellation (ISDIC) (R. R. Muller and J.B. Huber, 1998) (A. Lampe et. al., Jan., 2001) (J.F. Robler J. B. Huber Nov., 2002) and for multiuser detection is proposed performing error search and correction. Analysis by simulations shows for the considered downlink scenario that the bit error ratio of a matched filter (MF) ISDIC can he lowered by a factor of nearly 100 for high signal-to-noise ratios with the subsequent second stage approaching the performance of a more complex minimum mean-squared error (MMSE) ISDIC. Furthermore, the MMSE ISDIC can he improved by the proposed second stage by up to 0.5 dB. It is shown that the ISDIC scheme with additional second stage can approach the matched filter bound up to 1 dB for the analyzed channel and 4QAM transmission.