Covert Performance of Pinching-Antenna Enhanced Non-Orthogonal Multiple Access Communications

Abstract

This letter investigates the covert performance of a pinching-antenna system (PASS) assisted non-orthogonal multiple access (NOMA) network in a heterogeneous propagation environment. In the considered setup, a pinching antenna is deployed along a dielectric waveguide to flexibly control the radiation position and enhance spatial diversity. Two non-colluding user-specific wardens located in different regions attempt to detect the covert transmission of the legitimate NOMA users. Closed-form expressions for the false alarm probability and missed detection probability for an individual warden are derived by exploiting the statistical properties of the PASS geometry and the Gaussian–Chebyshev quadrature method, based on which the corresponding detection error probability (DEP) is obtained. Numerical results demonstrate that PASS-assisted NOMA significantly improves covert communication performance and increases the warden’s detection uncertainty compared with conventional antenna systems (CASS) assisted NOMA and PASS-assisted orthogonal multiple access (OMA). Furthermore, the impact of imperfect channel state information (CSI) at the wardens on the covert detection performance is also analyzed.