In this paper, we consider the information leakage and outage probabilities of a multipleinput 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. INDEX TERMSCooperative attack, Energy harvesting, Information leakage probability, Internet of Things, NOMA, UAV friendly jammer.

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In this paper, we analyze the secrecy outage probability (SOP) and the fairness of average packet transmission time for a non-orthogonal multiple access (NOMA) system which consists of a base station (BS) and two legal NOMA users in the presence of an eavesdropper (Eve). In order to extract the superimposed signal, the Eve is considered in two modes, i.e., successive interference cancellation (SIC) mode and parallel interference cancellation (PIC) mode. Accordingly, we analyze the secrecy performance of the considered system by deriving a new exact expression for SOP. Furthermore, the optimal power allocation between two legal users is determined such that the average transmission time from BS to two legitimate users are approximately equal to achieve the fairness of average packet transmission time. Monte Carlo simulations are provided to verify our analytical results. INDEX TERMS NOMA, secrecy outage probability, packet timeout probability, fairness of average transmission time.

Recently, non-orthogonal multiple access (NOMA) has been considered as a promising technique in 5G network, and many investigations have addressed on the physical layer security to improve the security performance. In this paper, an alternative problem, where the eavesdropping process is considered as a legal activity, will be analyzed to track suspicious communications. More specifically, we study a wireless surveillance system in which the legitimate monitor is equipped with multi-antenna to overhear the messages between the suspicious receiver and the suspicious transmitter. Suspicious users are grouped into pairs and use the NOMA technique to transmit signals to a suspicious base station. Meanwhile, the legitimate monitor (LM) simultaneously transmits jamming signals, listens to suspicious links, decodeand-forward (DF) the eavesdropped information to the legitimate eavesdropper (LE). Based on the proposed mechanism, we investigate the power allocation policies for jamming signals of the legitimate monitor under deterministic and non-deterministic interference channel. Accordingly, we derive the closed-form expression of the successful eavesdropping probability for the best and the worst user to evaluate the system performance. Monte Carlo simulations are provided to verify our analytical results.