Performance analysis of non-linear constellation precoded NOMA over Rayleigh fading channel

• NOMA is an advanced technology aimed at enhancing wireless system efficiency and managing increasing data traffic. • NCP is utilized for its maximum distance separable codes, boosting diversity gain. • The proposed NCP-NOMA scheme involves separate precoding of data for the far user (FU) and near user (NU), binary codeword generation, and QAM modulation before combining and transmitting the codewords. • Performance analysis through Monte Carlo simulations reveals that the NCP-NOMA scheme achieves a 6dB diversity gain with a bit error rate (BER) of 10^(-3), outperforming the conventional NOMA system. • Results show that integrating the NCP encoder in NOMA yields a 6 dB diversity gain, achieving a lower BER. • The impact of varying power allocation and the distance between the far user (FU) and near user (NU) is examined, confirming that optimal power allocation can further enhance BER performance. Non-orthogonal multiple access (NOMA), an advanced technology for 5G and beyond, has emerged as a promising solution to address the escalating wireless data traffic and enhance the efficiency of wireless systems. Nonlinear constellation precoding (NCP) improves the diversity gain using the maximum distance separable codes property. In this paper, we propose a novel (NCP-NOMA) scheme to enhance the diversity performance of the NOMA system. NCP pre-codes the far user (FU) and near user (NU) data separately and the binary codeword is obtained. The codeword is then subjected to QAM modulation, followed by superimposing the FU and NU codewords for NOMA transmission. This paper investigates the performance of the proposed system in terms of bit error rate (BER) for FU and NU using Monte Carlo simulation and compares the results with the conventional NOMA scheme. The simulation results demonstrate that integrating the NCP encoder achieves a 6dB diversity gain, resulting in a BER of 10 − 3 .