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.

Secrecy Outage Probability of a NOMA Scheme and Impact Imperfect Channel State Information in Underlay Cooperative Cognitive Networks Security performance and the impact of imperfect channel state information (CSI) in underlay cooperative cognitive networks (UCCN) is investigated in this paper. In the proposed scheme, relay R uses nonorthogonal multiple access (NOMA) technology to transfer messages     e 1    ,     e 2     from the source node S to User 1 (U     1    ) and User 2 (U     2    ), respectively. An eavesdropper (E) is also proposed to wiretap the messages of     U 1     and U     2    . The transmissionxe2x80x99s security performance in the proposed system was analyzed and performed over Rayleigh fading channels. Through numerical analysis, the results showed that the proposed systemxe2x80x99s secrecy performance became more efficient when the eavesdropper node E was farther away from the source node S and the intermediate cooperative relay R. The secrecy performance of U     1     was also compared to the secrecy performance of U     2    . Finally, the simulation results matched the Monte Carlo simulations well.