# Fluid Antenna Systems

arXiv: https://arxiv.org/abs/2005.11561 · HTML: https://mlsanity.com/paper/2005.11561/

## Key facts

- Cited by 9 papers in the map (data through 14 Oct 2026).
- First posted on arXiv 23 May 2020.

## Built on by (most cited first, 9 of 9)

- [Joint Transmit and Pinching Beamforming for Pinching Antenna Systems (PASS): Optimization-Based or Learning-Based?](https://mlsanity.com/paper/2502.08637/) (2025)
- [Deep Learning Optimization of Two-State Pinching Antennas Systems](https://mlsanity.com/paper/2507.06222/) (2025)
- [LNN-powered Fluid Antenna Multiple Access](https://mlsanity.com/paper/2507.08821/) (2025)
- [Balancing Latency and Model Accuracy for Fluid Antenna-Assisted LM-Embedded MIMO Network](https://mlsanity.com/paper/2508.01689/) (2025)
- [Joint Channel Estimation and Computation Offloading in Fluid Antenna-assisted MEC Networks](https://mlsanity.com/paper/2509.19340/) (2025)
- [A General Deep Learning Framework for Wireless Resource Allocation under Discrete Constraints](https://mlsanity.com/paper/2603.19322/) (2026)
- [Aerial Multi-Functional RIS in Fluid Antennas-Aided Full-Duplex Networks: A Self-Optimized Hybrid Deep Reinforcement Learning Approach](https://mlsanity.com/paper/2604.14309/) (2026)
- [A Unified Two-Stage Generative Diffusion Framework for Channel Estimation and Port Selection in Multiuser MIMO-FAS](https://mlsanity.com/paper/2605.29679/) (2026)
- [Deep Learning-Based Tri-Hybrid Multi-User MIMO Precoding: The Blessing of EM-Reconfigurable Antennas](https://mlsanity.com/paper/2609.39167/) (2026)

## Abstract (arXiv)

Over the past decades, multiple antenna technologies have appeared in many different forms, most notably as multiple-input multiple-output (MIMO), to transform wireless communications for extraordinary diversity and multiplexing gains. The variety of technologies has been based on placing a number of antennas at fixed locations which dictates the fundamental limit on the achievable performance. By contrast, this paper envisages the scenario where the physical position of an antenna can be switched freely to one of the N positions over a fixed-length line space to pick up the strongest signal in the manner of traditional selection combining. We refer to this system as a fluid antenna system (FAS) for tremendous flexibility in its possible shape and position. The aim of this paper is to study the achievable performance of a single-antenna FAS system with a fixed length and N in arbitrarily correlated Rayleigh fading channels. Our contributions include exact and approximate closed-form expressions for the outage probability of FAS. We also derive an upper bound for the outage probability, from which it is shown that a single-antenna FAS given any arbitrarily small space can outperform an L-antenna maximum ratio combining (MRC) system if N is large enough. Our analysis also reveals the minimum required size of the FAS, and how large N is considered enough for the FAS to surpass MRC.