On secrecy performance for IoT enabled SWIPT multi-relaying NOMA systems

In this paper, we evaluate the secrecy performance in terms of secrecy outage probability (SOP) for Internet of things (IoT) enabled multi-relaying non-orthogonal multiple access (NOMA) networks with energy harvesting over Nakagami-m fading channels. Specifically, we consider the scenario that a power-constrained source and N (N⩾1) IoT relays first harvest energy from a dedicated power beacon under a time switching mode, and then the source sends a confidential information to a legitimate user via a selected IoT relay, which forwards the decoded signal together with its own information data under a NOMA protocol to two legitimate users in the presence of an eavesdropper. Moreover, a two-stage relay selection criterion is also adopted to enhance the system’s secrecy performance. As a benchmark, we also adopt a random relay selection scheme to analyze the secrecy performance. To clearly reveal the benefits of our proposed schemes, the analytical expressions for SOP under those two schemes have been obtained and validated through Monte-Carlo simulations.