Center-Fed Pinching Antenna System (C-PASS): Modeling, Analysis, and Beamforming Design

2026-02-16

AI Summary

This work proposes a general modeling framework for the centrally fed pinched antenna system (C-PASS) to address the limitations in degrees of freedom (DoF) and power efficiency under high-attenuation scenarios. The study establishes the first theoretical model for C-PASS, revealing that its DoF scale linearly with both the number of ports and receive antennas. Building on closed-form derivations, the authors jointly optimize transmit precoding, power allocation, pinch locations, and radiation coefficients via an alternating optimization approach combined with block coordinate descent. Results demonstrate that a single-waveguide C-PASS outperforms conventional single-waveguide PASS in both DoF and power gain, and achieves over 10 dB sum-rate improvement compared to multi-waveguide PASS in high-attenuation environments.

Technology Category

• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Distributed Search
• Machine Learning: Hardware-aware ML

Application Category

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

Abstract

A generalized framework for the novel center-fed pinching antenna system (C-PASS) is proposed. Within this framework, closed-form expressions for the degree of freedom (DoF) and power scaling law of the proposed C-PASS are first derived. These theoretical results reveal that the achievable DoF scales linearly with the number of input ports, $M$, and the number of receive antennas, $K$. Furthermore, the derived power scaling laws demonstrate that the C-PASS achieves a power gain of order $\mathcal{O}(P_T M)$, where $P_T$ denotes the transmit power. Based on the proposed C-PASS modeling, a sum-rate maximization problem for the joint optimization of transmit and pinching beamforming is then formulated. To solve this highly coupled non-convex problem, an efficient alternating optimization algorithm is developed. More particularly, the transmit precoding and power splitting ratios are updated via derived closed-form solutions, while the pinching antenna positions and radiation coefficients are optimized using block coordinate descent (BCD) methods. Finally, our numerical results reveal that the single-waveguide C-PASS: 1) achieves superior DoF and power scaling laws compared to the single-waveguide PASS; and 2) outperforms the multi-waveguide PASS in high-attenuation regimes, yielding a substantial gain exceeding $10$ dB.

Problem

• center-fed pinching antenna system
• degree of freedom
• power scaling law
• beamforming design
• sum-rate maximization

Innovation

• center-fed pinching antenna system
• degree of freedom
• power scaling law
• beamforming design
• alternating optimization