Clipping Noise-Aided Message Passing Algorithm for SCMA-OFDM System

Sparse code multiple access combined with orthogonal frequency division multiplexing (SCMA-OFDM) is a promising wireless air-interface technology for fifth generation (5G) networks to support massive connections. The existing problem for SCMA-OFDM system is that the peak-to-average power ratio (PAPR) is unbearable high. The clipping method is often adopted to reduce the PAPR. However, the clipping brings extra noise to the SCMA-OFDM system. Due to the conventional message passing algorithm (C-MPA) didn't consider the clipping noise, it will cause the C-MPA decoding to be inaccurate and degrade the bit error rate performance. To tackle this issue, a novel clipping noise-aided MPA scheme, named CNA-MPA, which take both the additive white Gaussian noise (AWGN) and the clipping noise into consideration for decoding accurately is proposed. Simulation results show that the analysis of the clipping noise is accurate and the proposed CNA-MPA scheme leveraging both the AWGN and clipping noise can handle the phenomenon of the performance deterioration occurred in the C-MPA scheme at high E
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