Secure communication in mobile edge computing networks with RF energy harvesting
Dac-Binh Ha, Van-Long Nguyen, Van-Truong Truong, Anand Nayyar · 2024
In this chapter, we study the physical layer security (PLS) of a multiuser non-orthogonal multiple access (NOMA) radio frequency energy harvesting (RF EH) relaying system. The user selection scheme, decode-and-forward (DF) relay selection solution, users' quality of service (QoS) requirements, and time switching ratio of RF EH are considered for secure NOMA transmission. Specifically, we investigate the scenario that two legitimate user (LU) clusters with different priorities depend on their QoS requirements to offload their tasks to a server located at a base station by applying uplink/downlink NOMA with the help of multiple relays in the presence of a passive eavesdropper. To enhance the secrecy performance, we examine a relay selection scheme and a user selection method. In this context, to evaluate the secrecy performance, closed-form expressions of the existence probability of secrecy capacity and secrecy outage probability for selected LUs and relay are derived. Furthermore, we propose an optimization algorithm based on particle swarm optimization (PSO) to obtain an optimal parameter set, e.g., time switching ratio and power allocation ratio, to achieve the best secrecy performance for this considered system. To investigate the system's PLS performance, we simulate the system with essential parameters such as transmit power, power allocation coefficient, time switching ratio, number of users in clusters, and number of relays. Our theoretical results confirmed by simulation show that PLS performance can be improved by using an optimization algorithm or/and enlarging transmit power or/and increasing the number of users and relays. Moreover, the system performance under the proposed optimal algorithm and protocol is superior to that of the traditional OMA solution. Finally, these results also indicate that our proposed optimal algorithm achieves the best secrecy performance.