Joint Secrecy and Covertness Analysis of RSMA-Assisted AAV Communications With an Internal Eavesdropper and External Wardens

This article investigates the internal secrecy and external covertness of a mixed-trust autonomous aerial vehicle (AAV) communication system assisted by rate-splitting multiple access (RSMA). In this setting, a semi-trusted user with partial decoding capability poses an internal eavesdropping threat, while multiple distributed wardens attempt to detect the transmission from the AAV to the semi-trusted user, creating an external covertness challenge. To characterize these security aspects, a unified analytical framework is developed. First, the internal eavesdropping capability of the semi-trusted user is quantified by deriving a closed-form expression for its eavesdropping-success probability (ESP). Based on the outcome of the eavesdropping attempt, tractable expressions for the secrecy outage probability (SOP) of the legitimate user are obtained. Furthermore, the external covertness performance is analyzed by deriving closed-form false-alarm probability, missed-detection probability, and detection-error probability (DEP) for an individual warden, together with the optimal detection threshold and the corresponding minimum DEP. The cooperative global detection performance with multiple wardens is further characterized under conservative fusion rules. Extensive Monte Carlo simulations validate the analytical results and, through a joint evaluation of secrecy, reliability, and covertness metrics, illustrate the feasible operating regions enabled by RSMA power allocation in comparison with a nonorthogonal multiple access (NOMA) baseline. The results provide a comprehensive theoretical basis for the design of secure and covert AAV communication strategies in mixed-trust environments.