Performance Analysis of an Energy-Harvesting IoT System Using a UAV Friendly Jammer and NOMA Under Cooperative Attack

In this article, we consider the information leakage and outage probabilities of a multiple-input single-output (MISO) energy-harvesting (EH) Internet of Things (IoT) system in which a multiantenna ground base station (GBS) transmits messages to legitimate IoT destinations (LIDs) with the help of IoT relays (IRs) using non-orthogonal multiple access (NOMA) in the presence of a malicious jammer (MJ) and eavesdroppers (EAVs). The communication protocol is separated into two phases. In the EH phase, the IRs harvest energy from a power beacon (PB). In the information transmission (IT) phase, the communication process is further divided into two subphases: 1) The GBS broadcasts signals to the IRs using NOMA. Simultaneously, the MJ sends interfering signals to attack the IRs while the EAVs steal the confidential signals from the GBS, in a process called a cooperative attack. On the other hand, to protect the legitimate communication, an unmanned aerial vehicle (UAV) is used as a friendly jammer to defend against the EAVs. 2) A selected IR employs the time-switching-based relaying (TSR) technique to forward the received signal to the LIDs using NOMA. Similar to the first subphase, the LIDs are subjected to a cooperative attack, and the UAV attacks the EAVs in return. The secrecy performance of this communication protocol is characterized by deriving expressions for the information leakage probabilities (ILPs) for the LIDs' signals. A UAV altitude optimization algorithm is also proposed to achieve the best possible secrecy performance. Furthermore, we evaluate the system performance by deriving closed-form expressions for the outage probabilities (OPs). Accordingly, an algorithm is proposed to guarantee both the secrecy and system performance (in terms of the ILPs and OPs). Monte Carlo simulations are presented to verify our analytical results.