Multi-User PD-NOMA with unreliable backhaul links in a multiple EH relay network over Nakagami-m fading channels

In this paper, we analyze the performance of cooperative power-domain non-orthogonal multiple access systems (PD-NOMA) for multiple users in a multiple energy-harvesting (EH) relay network with unreliable backhaul links over Nakagami-m fading channels. In the proposed system, multi-destination users are allocated various powers and communicate with the best transmitter (Tx) via the best relay. EH relay employs a power-splitting relaying (PSR) architecture and an amplify-and-forward (AF) protocol. To evaluate the performance of each user and the overall system, closed-form analytical expressions for the outage probability (OP) and throughput over Nakagami-m fading channels are derived. Moreover, Monte Carlo simulations are used to verify the accuracy of the analytical results. In addition, the effects of key parameters of the system, such as the shape factor of the Nakagami-m channel model, power allocation, EH efficiency, power splitting ratio, and the number of relay nodes, on both the outage probability and throughput for multiple NOMA users are analyzed. These results show that the proposed PD-NOMA system offers better user-fairness in comparison with the conventional orthogonal multiple-access (OMA) system. (C) 2021 Elsevier B.V. All rights reserved.