Robust Fluid-Antenna Assisted Covert ISAC via Joint Beamforming and Position Optimization

Abstract

This paper investigates a FA-assisted covert integrated sensing and communication (ISAC) system, where fluid antenna (FA) reconfiguration brings extra spatial degrees of freedom (DoFs) to boost both sensing performance and covert communication. We maximize the worst-case sensing mutual information (MI) via joint optimization of dual-functional beamformers and transmit FA positions, subject to Bob’s QoS constraint, covertness requirement at Willie, transmit power budget, physical mobility limits of FAs, and bounded CSI uncertainties. To tackle the resultant nonconvex optimization problem, we develop an alternating optimization (AO) algorithm based on the Dinkelbach transformation, semidefinite programming (SDP), the $\mathcal{S}$-procedure, and successive convex approximation (SCA). Simulation results validate the effectiveness of our proposed scheme and demonstrate obvious MI enhancement while ensuring reliable covert transmission.