Modeling and Beamforming Optimization for Pinching-Antenna Systems

2025-02-09

AI Summary

This work addresses the challenge of establishing low-power, highly reconfigurable line-of-sight (LoS) links in flexible wireless communications. We propose the Pinching-Antenna Systems (PASS) framework, jointly optimizing transmission and pinching-based beamforming. Our key innovation is modeling passive pinching antennas as physics-driven open-circuit directional couplers, enabling a dielectric waveguide coupling signal model and supporting both equal and proportional power allocation mechanisms. Leveraging coupled-mode theory and directional coupler modeling, we design a penalty-function-based alternating optimization algorithm and a low-complexity zero-forcing (ZF) scheme—both unifying support for continuous and discrete antenna activation patterns. Experiments demonstrate over 95% transmit power reduction versus conventional and massive MIMO baselines; the ZF algorithm achieves near-optimal performance relative to the penalty-based method; and discrete activation incurs negligible loss, while proportional power allocation matches the performance of equal-power allocation.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• User Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation

Abstract

The Pinching-Antenna SyStem (PASS) is a revolutionary flexible antenna technology designed to enhance wireless communication by establishing strong line-of-sight (LoS) links, reducing free-space path loss and enabling antenna array reconfigurability. PASS uses dielectric waveguides with low propagation loss for signal transmission, radiating via a passive pinching antenna, which is a small dielectric element applied to the waveguide. This paper first proposes a physics-based hardware model for PASS, where the pinching antenna is modeled as an open-ended directional coupler, and the electromagnetic field behavior is analyzed using coupled-mode theory. A simplified signal model characterizes the coupling effect between multiple antennas on the same waveguide. Based on this, two power models are proposed: equal power and proportional power models. Additionally, a transmit power minimization problem is formulated/studied for the joint optimization of transmit and pinching beamforming under both continuous and discrete pinching antenna activations. Two algorithms are proposed to solve this multimodal optimization problem: the penalty-based alternating optimization algorithm and a low-complexity zero-forcing (ZF)-based algorithm. Numerical results show that 1) the ZF-based low-complexity algorithm performs similarly to the penalty-based algorithm, 2) PASS reduces transmit power by over 95% compared to conventional and massive MIMO, 3) discrete activation causes minimal performance loss but requires a dense antenna set to match continuous activation, and 4) the proportional power model yields performance comparable to the equal power model.

Problem

• Optimizing beamforming for Pinching-Antenna Systems
• Minimizing transmit power in wireless communication
• Enhancing signal transmission with low propagation loss

Innovation

• Dielectric waveguides reduce signal loss
• Physics-based model optimizes antenna coupling
• Zero-forcing algorithm minimizes transmit power