Scaling Factor Aided Iterative Multiuser Receiver for Sparse Code Multiple Access

Sparse code multiple access (SCMA) is a promising nonorthogonal multiple access scheme for the 5G system. In this letter, we introduce a scaling factor (SF) to scale the extrinsic information exchanged between the detector and the decoders to further improve the performance of iterative multiuser receiver (IMR) in SCMA. Appropriate SF is selected by using the extrinsic information transform chart analysis. Simulation results indicate that compared with the standard IMR, the proposed SF aided IMR scheme can achieve obvious gain at the performance and convergence speed under the additive white Gaussian noise and the Rayleigh fading channels.