A capacity-approaching multi-user BICM-ID scheme for multiple access channel

A multi-user access scheme is proposed by combining bit-interleaved coded modulation with iterative demapping and decoding (BICM-ID) and multi-user detection (MUD), which is called MU-BICM-ID in this paper. In the proposed scheme, amplitude-phase shift keying (APSK) constellation and serial-concatenated convolutional code (SCCC) are adopted as coded modulation scheme. Unlike traditional orthogonal multiple access (OMA) or successive interference cancellation (SIC) based superposition coding, as a practical implementation of simultaneous decoding, MU-BICM-ID can approach any point on the upper boundary of the capacity region for multiple access channel (MAC) at relative high spectrum efficiency. The extrinsic information transfer (EXIT) analysis results show that, for the case of two users both with 1/2-rate and 16-APSK over Gaussian MAC (GMAC), the reception signal-to-noise ratio (SNR) thresholds of two users are close to the theoretical limit, which is also verified by BER simulation results.