arXiv subjects

Pigi P. Papanikolaou

Publications and source records attributed to Pigi P. Papanikolaou.

3 recordsLinked to original sources

arXiv2026

Secure ISAC with Sensing Privacy under Eavesdropper Uncertainty

This paper investigates the joint protection of confidential data and legitimate-user directional information in integrated sensing and communication (ISAC) networks. We consider a multiuser downlink in which passive multi-antenna eavesdroppers (Eves) attempt to decode confidential signals while exploiting legitimate-user reflections for unauthorized angular sensing. To address both threats, we develop a robust covariance-design framework that jointly limits Eve decoding, maintains the transmitter's accuracy in estimating the Eves' directions and shifts the dominant passive-sensing response toward prescribed deceptive directions. A Bayesian angular prior and the corresponding Bayesian Cramer-Rao bound (BCRB) characterize the transmitter's eavesdropper-angle estimation accuracy. Angular uncertainty is represented through geometry-consistent samples, such that each candidate Eve direction jointly determines the corresponding transmitter-Eve channel, user-Eve bearing, and deceptive direction. The resulting design balances worst-user secrecy, sensing accuracy, sensing privacy, and deception power. Robust Eve-decoding constraints are handled through finite sufficient conditions with intersample margins, while continuous ghost dominance is enforced using interval sum-of-squares (SOS) constraints. The resulting nonconvex problem is addressed through successive convex approximation (SCA) and semidefinite relaxation. Numerical results show that the proposed design effectively preserves secrecy and sensing privacy under Eve-angle uncertainty, provides controlled angular deception in single- and multiple-Eve scenarios, and outperforms benchmarks.

eess.SP↗

arXiv2025

Physical Layer Security with Artificial Noise in MIMO Pinching-Antenna Systems

As next-generation wireless networks emerge, security is becoming a critical performance metric. However, conventional multiple-input-multiple-output (MIMO) systems often suffer from severe path loss and are vulnerable to nearby eavesdroppers due to their fixed-antenna configurations. Pinching-antenna systems (PASs) offer a promising alternative, leveraging reconfigurable pinching antennas (PAs) positioned along low-loss dielectric waveguides to enhance channel conditions and dynamically mitigate security threats. In this paper, we propose an artificial noise (AN)-aided beamforming framework for the PAS downlink that maximizes the secrecy rate (SR) by jointly optimizing the information beams, the AN covariance, and the PA positions. We examine both perfect and imperfect channel state information (CSI) for the eavesdropper's channel. For the latter, location errors are mapped via a Jacobian into an ellipsoidal channel uncertainty set to accurately formulate the problem. We derive a closed-form solution for the single-waveguide scenario, yielding the optimal PA location and an information/AN power-splitting rule. For multiple waveguides and users, we develop a deep neural network (DNN)-aided joint optimizer that outputs beams, AN, and PA placements. Numerical results demonstrate that the proposed scheme improves SR consistently over PAS baselines in single- and multi-user settings under both perfect and imperfect CSI.

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arXiv2025

Secrecy Rate Maximization with Artificial Noise for Pinching-Antenna Systems

Security is emerging as a critical performance metric for next-generation wireless networks, but conventional multiple-input-multiple-output (MIMO) systems often suffer from severe path loss and are vulnerable to nearby eavesdroppers due to their fixed-antenna configurations. Pinching-antenna systems (PAS) offer a promising alternative, leveraging reconfigurable pinching antennas (PAs) positioned along low-loss dielectric waveguides to enhance channel conditions and dynamically mitigate security threats. In this paper, we propose an artificial noise (AN)-based beamforming scheme for downlink transmissions in PAS, with the goal of maximizing the secrecy rate. A closed-form solution is derived for the single-waveguide scenario, while an alternating optimization approach addresses more complex multiple waveguide setups. Numerical results show that the proposed scheme significantly outperforms conventional MIMO and existing PAS security schemes.

eess.SP↗