A Very Fast Joint Detection for Polar-Coded SCMA

We propose a very fast-convergence joint iterative detection and decoding (JIDD) scheme for channel-coded sparse code multiple access (SCMA). In the conventional JIDD, all users’ channel iterations are performed in parallel after variable nodes SCMA factor graph updated. The proposed JIDD scheme, however, slices into per-user decoding, inserts them deeply graph. By doing this, message enhancement by immediately propagates to connected messages graph, even within one passing algorithm iteration, while maintaining same total computational complexity per iteration. Numerical results confirm that various link scenarios, requires only two or three BER convergence, more than six iterations. downlink achieves an faster convergence rate. Moreover, uplink scenario with perfect power control, converged of is quite bit lower get level as scheme. Consequently, thanks fast dramatically reduces overall achieving convergence. addition, rate compensates multi-user latency issue, which inherent sequential algorithms, issue further overcome employing group-wise version