Robust Secure Beamforming Design for Cooperative Cognitive Radio Nonorthogonal Multiple Access Networks

By the integration of cooperative cognitive radio (CR) and nonorthogonal multiple access (NOMA), CR NOMA networks can improve spectrum efficiency wireless significantly. Due to openness exposure signals, secure communication is an important issue for networks. In this paper, we investigate physical layer security design Our objective achieve maximum secrecy rate secondary user by designing optimal beamformers artificial noise covariance matrix at multiantenna transmitter under quality-of-service primary transmit power constraint transmitter. We consider practical case that channel state information (CSI) eavesdropper imperfect, model imperfect CSI worst-case model. show robust maximization problem be transformed a series semidefinite programmings based on S-procedure rank-one relaxation. also propose effective method recover solution. Simulations are provided effectiveness our proposed algorithm with comparison nonrobust traditional orthogonal schemes.