Wireless secure communication method using reconfigurable intelligent surface-non-orthogonal multiple access under complex channel conditions

A wireless secure communication method using reconfigurable intelligent surface-non-orthogonal multiple access (RIS-NOMA) under complex channel conditions, wherein the RIS-NOMA refers to a RIS-NOMA communication system comprises:

• a base station (BS), a reconfigurable intelligent surface (RIS), a legitimate NOMA user, and an eavesdropper (Eve);
• the legitimate NOMA user comprises a legitimate remote user Dm and a legitimate near user Dn, and the base station communicates with the RIS;
• the RIS communicates with the legitimate NOMA user;
• the Eve intercepts a signal transmitted by the RIS;
• an arbitrary channel link obeys K-u shadow fading;
• each node in the RIS-NOMA communication system encounters a residual hardware impairment (RHI);
• the method comprising:
• 1) calculating a signal to interference plus distortion noise ratio (SIDNR) for the legitimate NOMA user and the eavesdropper in the presence of RHI in the RIS-NOMA communication system;
• 2) approximating a probability density function and cumulative distribution function for the k-u shadow fading;
• 3) calculating an outrage probability of the legitimate NOMA user and an intercept probability of the eavesdropper;
• and
• 4) transforming a calculation of the outrage probability of the legitimate NOMA user and the intercept probability of the eavesdropper into solving a cumulative distribution function of equivalent channel coefficients of corresponding joint channels, whereby measuring physical layer secure transmission performance of the system.