Movable-Antenna-Aided Covert ISAC-NOMA Networks: Joint Antenna Positioning and Resource Allocation

Integrated sensing and communication (ISAC) systems face critical security vulnerabilities when dual-functional waveforms are used for covert operations, as static antenna architectures inherently lack the spatial agility to harmonize communication reliability, covertness, and sensing accuracy. To address this challenge, we propose a novel movable antenna (MA)-assisted covert ISAC framework integrated with non-orthogonal multiple access (NOMA), where a multi-antenna ISAC base station (BS) dynamically serves two types of user-pairs, public pairs demanding high throughput and covert pairs requiring low-probability-of-detection transmissions, through shared communication-and-sensing (C&S) beams. Each user, in a pair, is equipped with a single MA to enable dynamic spatial reconfiguration and obscure covert signals from warden. To achieve these goals, we minimize the Cramér-Rao bound (CRB) for target estimation while satisfying communication rate requirements, covertness constraints, as well as power allocation and successive interference cancellation (SIC) feasibility. The formulated problem involves highly coupled variables of the transmit beamforming vectors, the NOMA power coefficients, and the MA position vectors of the users. The paper solves the resulting non-convex optimization problem using a block coordinate descent (BCD) algorithm that decomposes it into two subproblems: 1) beamforming and power allocation via successive convex approximation (SCA) augmented with the proper penalty correction step, and 2) MA position optimization using gradient-assisted SCA. Extensive simulations demonstrate significant gains and trade-offs over fixed position antennas and orthogonal multiple access benchmarks.