Discrete Diffusion for Port Selection in Multiuser Pinching-Antenna Systems
Abstract
Pinching-antenna systems (PASS) reconfigure wireless channels by activating radiating elements at selected locations along dielectric waveguides. Port selection is a core issue in improving the performance of multiuser PASS systems. In this paper, we study joint port selection and precoder design for multiuser sum rate maximization, which leads to a large-scale nonconvex mixed-integer problem coupling discrete port selection with continuous precoder design. We propose a discrete diffusion method that does not require optimal or near-optimal port selection solutions as training labels and recasts the resulting optimization problem as sampling from a target distribution. Instead, we learn a potential function from local objective differences between neighboring feasible realizations. The learned potential is incorporated into a Metropolis--Hastings sampling rule to guide a parallel diffusion process while preserving the port selection constraints. Simulation results show that the proposed method approaches exhaustive search within a 0.30% sum rate gap while achieving over 150× speedup, and outperforms state-of-the-art methods including greedy and beam search. In particular, it also achieves an 18.8× speedup over greedy search.
Related
- A Unified Two-Stage Generative Diffusion Framework for Channel Estimation and Port Selection in Multiuser MIMO-FAS
- Impact of Antenna Position Errors on TDMA and NOMA in Pinching-Antenna Systems
- S-PASS: Star-Topology Pinching-Antenna Systems with Pipelined Antenna Pre-Positioning
- VGAS: Variance-Reduced Guidance and Adaptive Selection for Training-Free Reward Alignment in Discrete Diffusion
- Secrecy Sum-Rate Maximization for RSMA-Enabled Pinching-Antenna Systems
BibTeX
@misc{sun2026discrete,
title = {{Discrete Diffusion for Port Selection in Multiuser Pinching-Antenna Systems}},
author = {Wenxuan Sun and Mingjie Shao and Yanqing Xu and Ya-Feng Liu},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.32258},
eprint = {2609.32258},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.32258},
note = {CC0},
}
RIS
TY - UNPB
TI - Discrete Diffusion for Port Selection in Multiuser Pinching-Antenna Systems
AU - Wenxuan Sun
AU - Mingjie Shao
AU - Yanqing Xu
AU - Ya-Feng Liu
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2609.32258
UR - https://arxiv.org/abs/2609.32258
AB - Pinching-antenna systems (PASS) reconfigure wireless channels by activating radiating elements at selected locations along dielectric waveguides. Port selection is a core issue in improving the performance of multiuser PASS systems. In this paper, we study joint port selection and precoder design for multiuser sum rate maximization, which leads to a large-scale nonconvex mixed-integer problem coupling discrete port selection with continuous precoder design. We propose a discrete diffusion method that does not require optimal or near-optimal port selection solutions as training labels and recasts the resulting optimization problem as sampling from a target distribution. Instead, we learn a potential function from local objective differences between neighboring feasible realizations. The learned potential is incorporated into a Metropolis--Hastings sampling rule to guide a parallel diffusion process while preserving the port selection constraints. Simulation results show that the proposed method approaches exhaustive search within a 0.30% sum rate gap while achieving over 150× speedup, and outperforms state-of-the-art methods including greedy and beam search. In particular, it also achieves an 18.8× speedup over greedy search.
ER -