Two Layer Security for Confidentiality in User Assisted Cooperative Noma System

User-Assisted Cooperative Non-orthogonal multiple access (UA-CNOMA) is a promising radio access technique for 5G networks allowing multiple users to share the same time-frequency resource. However, as the number of connected users continues to grow, ensuring data security has become a critical concern. This paper proposes a two-layer security scheme based on Physical Layer Security (PLS) and chaotic encryption to enhance the confidentiality of user data transmission in UA-CNOMA systems. The proposed system incorporates a user-assisted relay and employs chaotic encryption with a logistic map at the transmitter. To further enhance security, the control values of the logistic map are encrypted using PLS. The performance of the proposed scheme is evaluated to demonstrate its superiority over traditional PLS-based NOMA systems. It is inferred from the simulation that the proposed scheme provides enhanced confidentiality in data transmission than the existing techniques.