BER and HPA Nonlinearities Compensation for Joint Polar Coded SCMA System over Rayleigh Fading Channels

Sparse Code Multiple Access (SCMA) and Polar Coded (PC) have received a huge interest from researchers and considered as promising techniques for future wireless communication systems. They can significantly improve the capacity of wireless communication and potentially offer an energy efficiency. It is of huge importance to study the effects of nonlinear distortions due to high power amplifier (HPA) resulting from the joint combination of PC and SCMA signals. In this paper, we first study the performance of Joint Polar Coded SCMA system over Rayleigh fading channels, in terms of bit error rate (BER). Simulations are provided for various system parameters, such as polar lengths (polarN) and the input backoff (IBO). We also investigate the nonlinear effects of HPA in our system model and test the use of distortion cancellation technique, proposed in [1] based on neural networks (NNs) to significantly improve the system performance via eliminating the HPA nonlinearities at transmitter and receiver sides (Predistortion and Post-distortion). Finally, we showed, through numerical results, that the use of the Rayleigh channel fading affects the BER performance compared to the Gaussian one.