Rate Maximization for Multi-Waveguide PASS: A Hierarchical User Scheduling and Joint Optimization Framework

2026-05-28

AI Summary

This work addresses the sum-rate limitation in multi-waveguide Pinching-Antenna Systems (PASS) caused by waveguide propagation loss and coupling effects. For the first time, it explicitly models these loss and coupling mechanisms and proposes a joint optimization framework that integrates hierarchical user scheduling (HUS) to mitigate path loss and inter-user interference, Lagrangian dual and fractional programming for power allocation, and one-dimensional search for optimizing the pinching antenna position. The proposed approach significantly outperforms random pairing and maximum ratio transmission schemes in terms of sum rate, demonstrating that accurate modeling of propagation loss and coupling effects is crucial for enhancing PASS performance.

Abstract

Pinching-antenna systems (PASS) have emerged as a promising flexible-antenna architecture capable of dynamically reconfiguring wireless channels by activating dielectric particles along waveguides. The sum rate maximization problem in multi-waveguide PASS is investigated in this study. Both in-waveguide propagation loss and coupling effects are explicitly modeled. To tackle the optimization problem, a hierarchical user scheduling (HUS) algorithm is proposed. The HUS algorithm minimizes the sum of squared distances between users and their associated waveguides to mitigate path loss. Additionally, spatially separated users are assigned within each time slot to reduce inter-user interference. Furthermore, a joint optimization framework integrating power allocation and pinching-antenna (PA) positioning is developed to further improve system sum rate. Specifically, PAs' positions are optimized via one-dimensional search, while the power allocation problem is solved by using the Lagrangian duality and fractional programming. Numerical results show that the HUS algorithm clearly outperforms random pairing, and the proposed power allocation algorithm shows a marked performance improvement over the maximum ratio transmission algorithm. Moreover, the results explicitly demonstrate the considerable impact of in-waveguide propagation loss and coupling effects on the performance of PASS.

Problem

• sum rate maximization
• multi-waveguide PASS
• propagation loss
• coupling effects
• user scheduling

Innovation

• Pinching-Antenna System (PASS)
• Hierarchical User Scheduling
• Joint Optimization
• Power Allocation
• Waveguide Propagation Loss