Robust Beamforming for Pinching-Antenna Systems

TL;DR

This paper introduces a robust beamforming framework for pinching-antenna systems that accounts for channel uncertainty, optimizing antenna placement and beamforming to improve performance over traditional fixed-antenna setups.

Contribution

It develops a novel robust beamforming approach for PASS, including solutions for lossy and lossless waveguides, and demonstrates enhanced robustness against channel uncertainty.

Findings

Proposed a second-order cone programming solution for lossy waveguides.

Derived a closed-form maximum ratio transmission solution for lossless waveguides.

PASS outperforms fixed-antenna systems under channel uncertainty.

Abstract

Pinching-antenna system (PASS) mitigates large-scale path loss by enabling flexible placement of pinching antennas (PAs) along the dielectric waveguide. However, most existing studies assume perfect channel state information (CSI), overlooking the impact of channel uncertainty. This paper addresses this gap by proposing a robust beamforming framework for both lossy and lossless waveguides. For baseband beamforming, the lossy case yields an second-order cone programming-based solution, while the lossless case admits a closed-form solution via maximum ratio transmission. The PAs' positions in both cases are optimized through the Gauss-Seidel-based method. Numerical results validate the effectiveness of the proposed algorithm and demonstrate that PASS exhibits superior robustness against channel uncertainty compared with conventional fixed-antenna systems. Notably, its worst-case achievable rate can even exceed the fixed-antenna baseline under perfect CSI.