Performance Analysis of CR-Enabled AmBC NOMA Under IQI and Sensitivity Constraints

Considering tag sensitivity and in-phase and quadrature-phase imbalance (IQI), this paper investigates the reliability and security of a cognitive radio (CR)-aided ambient backscatter communication (AmBC) non-orthogonal multiple access (NOMA) system. Herein, the source communicates with its NOMA users in the presence of an eavesdropper, and to bolster security, artificial noise (AN) injection is introduced. The effects of non-ideal successive interference cancellation (SIC) and AN removal on system performance are also examined. Subsequently, outage probabilities (OPs) and interception probabilities (IPs) of the tag and NOMA signals are derived, with asymptotic results for further insights. Finally, simulation results are provided to validate the theoretical analysis. It is observed that both reliability and security remain stable even as interference or maximum transmission power increases up to a certain threshold. Furthermore, the reliability under NOMA mechanism outperforms that of orthogonal multiple access. Notably, IQI can consistently enhance the confidentiality of NOMA but selectively strengthen backscatter transmission, albeit at the expense of reliability. This paper comprehensively underscores the potential for real-world implementation by incorporating sensitivity constraints, IQI, AN, and imperfect SIC into the system model.