Hybrid Uplink-Downlink NOMA for Secure Coordinated Multi-Point Networks

In this paper, we propose a novel hybrid uplink-downlink non-orthogonal multiple access scheme (HUD-NOMA) for coordinated multi-point (CoMP) networks. By using NOMA technology and network coding for effective interference control, the proposed HUD-NOMA scheme improves the transmission rate of edge users. Although there is a slight decrease in signal reception reliability to the users with strong received signals, the sum rate of the whole system is increased. Since the intended interferences are effectively manageable by the legitimate users, the HUD-NOMA scheme is resistant to eavesdroppers. Then, by using a stochastic geometry approach, we further analyze the secrecy outage probability (SOP) of the CoMP network applying the proposed HUD-NOMA. Numerical results verify that our scheme outperforms the existing method in terms of higher transmission rates and lower SOP.