Robust and Secure Blockage-Aware Pinching Antenna-assisted Wireless Communication

In this work, we investigate a blockage-aware pinching antenna (PA) system designed for secure and robust wireless communication. The considered system comprises a base station equipped with multiple waveguides, each hosting multiple PAs, and serves multiple single-antenna legitimate users in the presence of multi-antenna eavesdroppers under imperfect channel state information (CSI). To safeguard confidential transmissions, artificial noise (AN) is deliberately injected to degrade the eavesdropping channels. Recognizing that conventional linear CSI-error bounds become overly conservative for spatially distributed PA architectures, we develop new geometry-aware uncertainty sets that jointly characterize eavesdroppers position and array-orientation errors. Building upon these sets, we formulate a robust joint optimization problem that determines per-waveguide beamforming and AN covariance, individual PA power-ratio allocation, and PA positions to maximize the system sum rate subject to secrecy constraints. The highly non-convex design problem is efficiently addressed via a low computational complexity iterative algorithm that capitalizes on block coordinate descent, penalty-based methods, majorization-minimization, the S-procedure, and Lipschitz-based surrogate functions. Simulation results demonstrate that sum rates for the proposed algorithm outperforms conventional fixed antenna systems by 4.7 dB, offering substantially improved rate and secrecy performance. In particular, (i) adaptive PA positioning preserves LoS to legitimate users while effectively exploiting waveguide geometry to disrupt eavesdropper channels, and (ii) neglecting blockage effects in the PA system significantly impacts the system design, leading to performance degradation and inadequate secrecy guarantees.