In this paper, we analyze the bit error rate (BER) performance of a new modified structure of multitone code-division-multiple-access (MT-CDMA) system that is serial-to-parallel (S/P)-Replica MT-CDMA. It is shown that with the same bandwidth, the S/P-Replica MT-CDMA system outperforms the conventional system that we name it S/P MT-CDMA. We also propose a novel bandwidth-efficient-channel-coding-scheme (BECCS) based on super-orthogonal-code (SOC)-assisted serially concatenated turbo code (SCSOC) for S/P-Replica MT-CDMA system so that by using it, the coded system without extra bandwidth, significantly improves the performance of an uncoded system over fading channel.