A novel detection and decoding receiver for Polar-Coded SCMA system

Sparse code multiple access (SCMA) and polar codes (PC) are two promising candidates for Future communication systems since they are capable of achieving high system capacity. In this paper, we develop a novel detection and decoding scheme for SCMA systems combined with channel coding candidate polar codes. First, we propose a separate detection and decoding (SDD) receiver for uplink communications. Then, we introduce a joint detection and decoding (JDD) receiver scheme. The investigation of system receiver is decomposed on message passing algorithm (MPA) based SCMA multiuser detection and soft cancellation (SCAN) algorithm based polar codes decoder. The separate and joint schemes are studied over additive white gaussian noise (AWGN) channels. JDD scheme yields a better performance gain. Moreover, the joint scheme has a lower computational complexity compared to the separate one. Numerical results show that when polar code length polar
_N
= 1024 and R = 1/2, under system loading 150%, JDD outperforms the SDD 1.8dB at BER = 10
^-2
and 3.3dB at BER = 10
^-6
over AWGN channels.