Finite-Aperture Fluid Antenna Array Design: Analysis and Algorithm
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arXiv
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| Auteurs principaux: | , , , , , |
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| Format: | Preprint |
| Publié: |
2026
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| _version_ | 1866909018969079808 |
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| author | Zhang, Zhentian Wong, Kai-Kit Jiang, Hao Ghadi, Farshad Rostami Shin, Hyundong Zhang, Yangyang |
| author_facet | Zhang, Zhentian Wong, Kai-Kit Jiang, Hao Ghadi, Farshad Rostami Shin, Hyundong Zhang, Yangyang |
| contents | Finite-aperture constraints render array design nontrivial and can undermine the effectiveness of classical sparse geometries. This letter provides universal guidance for fluid antenna array (FAA) design under a fixed aperture. We derive a closed-form Cramér--Rao bound (CRB) that unifies conventional and reconfigurable arrays by explicitly linking the Fisher information to the geometric variance of port locations. We further obtain a closed-form probability density function of the minimum spacing under random FAA placement, which yields a principled lower bound for the minimum-spacing constraint. Building upon these analytical insights, we then propose a gradient-based algorithm to optimize continuous port locations. Utilizing a simple gradient update design, the optimized FAA can achieve about a $30\%$ CRB reduction and a $42.5\%$ reduction in mean-squared error. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_18471 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Finite-Aperture Fluid Antenna Array Design: Analysis and Algorithm Zhang, Zhentian Wong, Kai-Kit Jiang, Hao Ghadi, Farshad Rostami Shin, Hyundong Zhang, Yangyang Information Theory Finite-aperture constraints render array design nontrivial and can undermine the effectiveness of classical sparse geometries. This letter provides universal guidance for fluid antenna array (FAA) design under a fixed aperture. We derive a closed-form Cramér--Rao bound (CRB) that unifies conventional and reconfigurable arrays by explicitly linking the Fisher information to the geometric variance of port locations. We further obtain a closed-form probability density function of the minimum spacing under random FAA placement, which yields a principled lower bound for the minimum-spacing constraint. Building upon these analytical insights, we then propose a gradient-based algorithm to optimize continuous port locations. Utilizing a simple gradient update design, the optimized FAA can achieve about a $30\%$ CRB reduction and a $42.5\%$ reduction in mean-squared error. |
| title | Finite-Aperture Fluid Antenna Array Design: Analysis and Algorithm |
| topic | Information Theory |
| url | https://arxiv.org/abs/2601.18471 |