Non-Orthogonal Multiple Access (NOMA) in Cooperative Relaying Power Line Communications

Most, if not all, existing studies on power line communication (PLC) systems as well as industrial PLC standards are based on orthogonal multiple access schemes such as orthogonal frequency-division multiplexing and code-division multiple access. Unlike those systems, we propose in this paper, for the first time, non-orthogonal multiple access (NOMA) for PLC systems. More specifically, we evaluate the performance of a dual-hop decode-and-forward relaying PLC system in terms of the average capacity. In this respect, accurate analytical expressions for the average capacity are derived. To quantitatively characterize the proposed system performance, we also analyze the average capacity of conventional cooperative relaying (CCR) PLC systems. In addition, Monte Carlo simulations are provided throughout to validate our analysis. The impact of several system parameters such as the branching, impulsive noise probability, cable lengths, the power allocation coefficients and input SNR are investigated. Results reveal that the capacity performance of the proposed NOMA-PLC system is superior compared to that of the CCR-PLC approach. It is also shown that NOMA-PLC can be more effective in mitigating electromagnetic compatibility issues associated with PLC and that increasing the network branches can degrade system performance. Moreover, optimizing the power allocation coefficients is found to be important to maximize the performance of the proposed system.