Secrecy Performance of Uplink-Downlink NOMA Network at Physical Layer

Physical layer security of a composite network, which includes both the uplink and downlink non-orthogonal multiple access (NOMA) system, has been analyzed. In this network, the relay is working as interface between the uplink and downlink NOMA system. Due to deep fading and shadowing, two legitimate destinations and the eavesdropper (EAV) are able to receive the information signals from the relay only. We have considered a scenario at the relay in which the relay decodes the strongest signal first when it does not know the transmit power of the information signals. To secure the confidential information, the jammer has been considered to secure the information from the EAV. For the considered model, the secrecy outage probability is analyzed as a performance metric using MATLAB based simulation. The optimal value of the relay transmit signal to noise ratio and the worst value of the transmit signal to noise ratio of the source one is indicated.