The optimization scheme for joint iterative detection and decoding of polar coded SCMA system.

• The PC-SCMA technology can enhance the performance of communication system. • JIDD scheme can make full use of the intermediate messages to improve performance. • S-JIDD can effectively reduce complexity and achieve ideal error performance. • Adding CRC early stopping criterion can further reduce the BER of the system. Polar coding and sparse code multiple access (SCMA) technique are excellent candidates for 5G, and have a promising prospect in optical communication, the joint design of polar coded sparse code multiple access (PC-SCMA) system is important to enhance the overall system performance. In this paper, a serial joint iterative detection and decoding scheme is proposed by passing message between serial max-log message passing algorithm and soft cancellation (SCAN) algorithm, the strategy can accelerate the algorithm convergence speed by reducing the number of required iterations, decrease the computational complexity and achieve ideal bit error rate (BER) performance. In order to further improve the BER performance, a cyclic redundancy check (CRC) is added in the joint iterative process as an early stopping criterion to avoid decoding divergence caused by a low signal to noise ratio (SNR). Simulation results demonstrate that the addition of a termination mechanism can obtain an excellent performance gain compares with the conventional JIDD algorithm. [ABSTRACT FROM AUTHOR]