Secure Transmission Design for Cooperative NOMA in the Presence of Internal Eavesdropping

The application of successive interference cancellation (SIC) introduces critical security risks to cooperative non-orthogonal multiple access (NOMA) systems in the presence untrustworthy network nodes, referred as internal eavesdroppers. To address this potential and reliability flaw, by assuming all users are untrusted, letter investigates effective secrecy throughput (EST) for a NOMA system, where near user serves an amplify-and-forward relay help forward information far user. Considering inverse power allocation SIC decoding order, novel jamming strategy is proposed enhance performance Gauss-Chebyshev approximations ESTs over Nakagami- ${m}$ channels derived. Asymptotic EST expressions provide further insights. Numerical results demonstrate that order both essential achieving positive rates users.