Covert performance analysis of integrated RIS and backscatter NOMA communication networks

In this work, we delve into the covertness performance of the reconfigurable intelligent surface (RIS) symbiotic ambient backscatter communication (AmBC) systems, where the RIS is partitioned into two zones to serve covert and public users. To impede with the monitor’s detection, the source deliberately transmits both information and interference signals. Specifically, we derive closed-form expressions for the detection error probability (DEP) and outage probabilities. Subsequently, the effective covert rate (ECR) is maximized by optimizing the power allocation factor and the number of each zone reflective elements. Finally, we investigate the energy efficiency (EE) of the considered system. Simulation results validate the accuracy of the analysis, underscoring that the RIS-segmented symbiotic AmBC systems can achieve better covertness by improving the interference cancellation capability and dividing the optimal RIS zones.