Exact secure outage probability performance of uplinkdownlink multiple access network under imperfect CSI

In this paper, we study uplink-downlink non-orthogonal multiple access (NOMA) systems by considering the secure performance at physical layer. considered system model, base station acts a relay to allow two users left side communicate with right side. By imperfect channel state information (CSI), need be studied since an eavesdropper wants overhear signals processed downlink. To provide metric, derive exact expressions of secrecy outage probability (SOP) and evaluating impacts main parameters on SOP metric. The important finding is that can achieve higher high signal noise ratio (SNR). Moreover, numerical results demonstrate tends constant SNR. Finally, our show power allocation factors, target rates are factors affecting NOMA systems.