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Autores principales: Zhang, Tong, Li, Qianren, Wang, Shuai, Ni, Wanli, Zhang, Jiliang, Wang, Rui, Wong, Kai-Kit, Chae, Chan-Byoung
Formato: Preprint
Publicado: 2025
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Acceso en línea:https://arxiv.org/abs/2509.15006
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author Zhang, Tong
Li, Qianren
Wang, Shuai
Ni, Wanli
Zhang, Jiliang
Wang, Rui
Wong, Kai-Kit
Chae, Chan-Byoung
author_facet Zhang, Tong
Li, Qianren
Wang, Shuai
Ni, Wanli
Zhang, Jiliang
Wang, Rui
Wong, Kai-Kit
Chae, Chan-Byoung
contents Fluid antenna system (FAS) revolutionizes wireless communications via utilizing position-flexible antennas that dynamically optimize channel conditions and mitigate multipath fading. This innovation is particularly valuable in indoor environments, in which signal propagation is severely degraded due to structural obstructions and complex multipath reflections. In this paper, we investigate the channel modeling and the joint optimization of antenna positioning, beamforming, and power allocation for indoor FAS. In particular, we propose a layout-specific channel model, and employ the novel group relative policy optimization (GRPO) algorithm for tackling the optimization problem. Compared to the state-of-the-art Sionna model, our model achieves an 83.3% reduction in computation time with an approximately 3 dB increase in root-mean-square error (RMSE). When simplified to a two-ray model, our model allows for a closed-form antenna position solution with near-optimal performance. For the joint optimization problem, our GRPO algorithm outperforms proximal policy optimization (PPO) and other baselines in sum-rate, while requiring only 50.8% computational resources of PPO, thanks to its group advantage estimation. Simulation results show that increasing either the group size or trajectory length in GRPO does not yield significant improvements in sum-rate, suggesting that these parameters can be selected conservatively without sacrificing performance.
format Preprint
id arxiv_https___arxiv_org_abs_2509_15006
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Indoor Fluid Antenna Systems Enabled by Layout-Specific Modeling and Group Relative Policy Optimization
Zhang, Tong
Li, Qianren
Wang, Shuai
Ni, Wanli
Zhang, Jiliang
Wang, Rui
Wong, Kai-Kit
Chae, Chan-Byoung
Information Theory
Fluid antenna system (FAS) revolutionizes wireless communications via utilizing position-flexible antennas that dynamically optimize channel conditions and mitigate multipath fading. This innovation is particularly valuable in indoor environments, in which signal propagation is severely degraded due to structural obstructions and complex multipath reflections. In this paper, we investigate the channel modeling and the joint optimization of antenna positioning, beamforming, and power allocation for indoor FAS. In particular, we propose a layout-specific channel model, and employ the novel group relative policy optimization (GRPO) algorithm for tackling the optimization problem. Compared to the state-of-the-art Sionna model, our model achieves an 83.3% reduction in computation time with an approximately 3 dB increase in root-mean-square error (RMSE). When simplified to a two-ray model, our model allows for a closed-form antenna position solution with near-optimal performance. For the joint optimization problem, our GRPO algorithm outperforms proximal policy optimization (PPO) and other baselines in sum-rate, while requiring only 50.8% computational resources of PPO, thanks to its group advantage estimation. Simulation results show that increasing either the group size or trajectory length in GRPO does not yield significant improvements in sum-rate, suggesting that these parameters can be selected conservatively without sacrificing performance.
title Indoor Fluid Antenna Systems Enabled by Layout-Specific Modeling and Group Relative Policy Optimization
topic Information Theory
url https://arxiv.org/abs/2509.15006