On the physical layer security of CR-NOMA assisted intelligent transportation networks

For the intelligent transportation system driven by mobile communication, we study the physical layer security (PLS) performance of the wiretap cooperative non-orthogonal multiple access (NOMA) network with an untrusted near primary user. To protect communication security, we propose an artificial noise-assisted overlay cognitive cooperation framework. The closed-form expressions of the outage probability (OP) for all users, the intercept probability (IP) of the untrusted primary user eavesdropping on primary and secondary network security information, and the approximate results under the high signal-to-noise ratio (SNR) are derived. Numerical results verify the theoretical analysis, and we conclude: 1) the OPs of all users decrease with the SNR increasing, and the OP of the untrusted user exists a ceiling; 2) increasing the SNR, the IPs of the untrusted user to the primary and secondary network security information increase until convergence to the same fixed constant; 3) reasonable configuration of parameters can better optimise system performance.