RF Energy Harvesting and Security Offloading Protocol for MEC-enabled NOMA Networks with Passive Eavesdropper

Mobile edge computing (MEC) and Non-orthogonal multiple access (NOMA) are two emerging technologies recently attracting significant attention. MEC enables offloading computation tasks from mobile devices (MDs) to proximity edge servers, while NOMA allows multiple MDs to share the frequency and time resources with power domain multiplexing. However, MD security and energy consumption remain critical in many communication scenarios, especially for resource-constrained devices. Radio frequency energy harvesting (RF EH) and physical layer security (PLS) have been proposed as promising solutions to this problem. In this paper, we investigate the RF EH for MEC-enabled NOMA networks, where an MD can harvest energy from the hybrid access point (HAP) and offload security to APs with the existence of a passive eavesdropper over Nakagami-m fading channel. Accordingly, we propose a security offloading protocol for the system, evaluated by the parameter secrecy successful computation probability (SSCP). We examine SSCP under various system parameters such as power transmit power, time switching ratio, task division ratio, bandwidth, and power allocation coefficient. Our results show that the system performance is improved if the optimal time switching ratio, the power allocation coefficient, is used.