{"ID":2829201,"CreatedAt":"2026-06-01T04:54:23.091178241Z","UpdatedAt":"2026-06-01T04:54:23.091178241Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2512.13941","arxiv_id":"2512.13941","title":"Fundamental Limits of Localization with Fluid Antenna Systems: A Fisher Information Analysis","abstract":"In this letter, we investigate the fundamental limits of localization in fluid antenna systems (FAS) utilizing a Fisher-information-theoretic framework. We develop a unified model to quantify the localization information extractable from time-of-arrival (ToA) and angle-of-arrival (AoA) measurements, explicitly capturing the synthetic aperture effects induced by FAS. Closed-form expressions are derived for the equivalent Fisher information matrix (EFIM) and the corresponding positioning error bound (PEB) in both user-side and base-station (BS)-side FAS configurations. Also, we propose optimal port-selection strategies based on greedy algorithms and convex relaxation to maximize the information gain under a constrained number of activated ports. Numerical results demonstrate that the proposed port-selection schemes can substantially tighten the PEB compared with random activation, thereby confirming the strong potential of FAS to enable high-precision localization. These results offer analytical insights and practical design guidelines for FAS-aided positioning in future-generation wireless networks","short_abstract":"In this letter, we investigate the fundamental limits of localization in fluid antenna systems (FAS) utilizing a Fisher-information-theoretic framework. We develop a unified model to quantify the localization information extractable from time-of-arrival (ToA) and angle-of-arrival (AoA) measurements, explicitly capturin...","url_abs":"https://arxiv.org/abs/2512.13941","url_pdf":"https://arxiv.org/pdf/2512.13941v1","authors":"[\"Abdelhamid Salem\",\"Kai-Kit Wong\",\"Hyundong Shin\",\"Yangyang Zhang\"]","published":"2025-12-15T22:23:20Z","proceeding":"eess.SP","tasks":"[\"eess.SP\"]","methods":"[]","has_code":false}