A novel bandwidth efficient SOC-based turbo coding scheme mid reduced complexity MUD for SA-based MC-CDMA systems

Multiuser-detection (MUD), turbo coding and smart-antennas (SA) are powerful techniques for enhancing the performance and capacity of MC-CDMA systems. Among the MUD algorithms, the maximum-likelihood (ML) method has the best performance but its complexity increases exponentially with the number of users and constellation size. In this paper, we first propose a novel bandwidth-efficient-channel-coding-scheme (BECCS) for a super-orthogonal-code (SOC)-based serially concatenated turbo code (SCSOC) so that by using it, the coded system without extra bandwidth significantly improves the performance of an uncoded system over a fading channel. Second, in order to reduce the complexity of the ML-based turbo MUD technique, an ML algorithm based on the sensitive-bits-algorithm (SBA) and a less-complex-norm-approximation (LCNA) based Euclidean distance is proposed for a SCSOC-based BECCS assisted coded MC-CDMA system accompanied by SA techniques at the receiver. Our analytical and simulation results show that from a performance perspective, at BER=10(-2), the proposed SCSOC-based BECCS assisted MC-CDMA system performs 4 dB better than SOC-based coded systems. The latter system has 5 dB gain in comparison with an uncoded one, all in the same bandwidth and over fading channels.