Secure GreenOriented Multiuser Scheduling for WirelessPowered Internet of Things In this paper, we consider the secure greenoriented multiuser scheduling for the wirelesspowered Internet of Things (IoT) scenario, in which multiple source sensors communicate with a controller assisted by an intermediate sensor with the existence of a passive tapping device. Due to the limited energy, all sensors must acquire energy from external power beacons (PBs). Specifically, for the security improvement, we introduce two multiuser scheduling schemes possessing the optimal PB chosen by the relay, i.e., the best source sensor is scheduled in a random way (BSR), while the best source sensor is decided by the best PB (BSBP). Furthermore, for every scheme, we derive the analytical expressions for the secrecy outage probability (SOP) and investigate the secure energy efficiency (SEE) optimization problem with constricted transmission power in PBs. Simulation results reveal that the BSBP scheme provides better secrecy performance, and elevating the PBs quantity or reducing both the ratio of distance from PBs to source users and the total communication distance to some extent is helpful for improving SEE. In addition, the timeswitching factor shows an important effect upon secrecy performance of the considered system.

Secure Communication in Cooperative SWIPT NOMA Systems with NonLinear Energy Harvesting and Friendly Jamming This paper studies the secure communication of a nonorthogonal multipleaccess (NOMA) relaying system in the presence of an eavesdropper in which the NOMA communication between a source and two users is assisted by an energyharvesting (EH) relay. The relay extracts a part of its received signal strength using a powersplitting (PS) policy then harvests energy using a nonlinear EH (NLEH) circuit. A friendly jammer sends jamming signals to help secure communication. The jammer is exploited as an additional energy source. A storeandtransmit (SaT) scheme which allows the EH relay to perform energy storing and information transmitting is proposed. For performance evaluation, the closedform expressions for three metrics, secrecy outage probability (SOP), average achievable secrecy rate (AASR) and average stored energy (ASE) are derived. These results enable studies on the effects of various system parameters, such as NOMA powerallocation factors, target secrecy rates, jammerxe2x80x99s location, and relayxe2x80x99s power levels, on the system performance.