Fluid antenna systems (FAS) offer a promising paradigm for enhancing wireless communication by exploiting spatial diversity, yet a rigorous analytical framework for their error probability has been notably absent. To this end, this paper addresses this critical gap by unveiling the \textbf{fundamental scaling laws} that govern the symbol error rate (SER) of FAS in realistic, spatially correlated channels. To establish these laws, we derive a tight, closed-form asymptotic expression for the SER applicable to a general class of modulation schemes. This result is pivotal as it establishes the fundamental scaling law governing the relationship between SER and the channel's spatial correlation structure. Based on this framework, we provide a complete characterization of the diversity and coding gains. The analysis culminates in a definitive design directive: SER can be fundamentally improved by expanding the antenna's movement space to increase diversity, while merely increasing port density within a constrained space yields diminishing returns.
We study the scaling laws of the signal-to-interference-plus-noise ratio (SINR) and the area spectral efficiency (ASE) in multi-antenna cellular networks, where the number of antennas scales with the base station (BS) spatial density $λ$, under the assumption of independent and identically distributed (i.i.d.) channels. We start with the MISO case with $N_t(λ)$ transmit antennas and a single receive antenna and prove that the average SINR scales as $\frac{N_t(λ)}λ$ and the average ASE scales as $λ\log\left(1+\frac{N_t(λ)}λ\right)$. For the MIMO case with single-stream eigenbeamforming and $N_r…
We study the scaling laws of the signal-to-interference-plus-noise ratio (SINR) and area spectral efficiency (ASE) in multi-antenna cellular networks, where the number of antennas scales with the base station (BS) spatial density $λ$. We start with the MISO case having $N_t(λ)$ transmit antennas and a single receive antenna and prove that the average SINR scales as $\frac{N_t(λ)}λ$ and the average ASE scales as $λ\log\left(1+\frac{N_t(λ)}λ\right)$. For the MIMO case with single-stream eigenbeamforming and $N_r(λ) \leq N_t(λ)$ receive antennas, we prove that the scaling laws of the conditional …
Fluid antenna represents a concept where a mechanically flexible antenna can switch its location freely within a given space. Recently, it has been reported that even with a tiny space, a single-antenna fluid antenna system (FAS) can outperform an L-antenna maximum ratio combining (MRC) system in terms of outage probability if the number of locations (or ports) the fluid antenna can be switched to, is large enough. This letter aims to study if extraordinary capacity can also be achieved by FAS with a small space. We do this by deriving the ergodic capacity, and a capacity lower bound. This let…
Fluid antenna is a novel technology that can make an antenna appear instantly at one of N preset locations in a predefined space. An important application is to adopt fluid antenna in a small space of mobile device for obtaining the tremendous diversity hidden in the small space. Previous results have revealed that a single-antenna fluid antenna system, even with a very small space, can outperform a multiple antenna maximum ratio combining (MRC) system if $N$ is large enough. This paper explores the potential of using fluid antenna for multiple access through performance analysis. Fluid antenn…
In this paper, we examine the benefits of multiple antenna communication in random wireless networks, the topology of which is modeled by stochastic geometry. The setting is that of the Poisson bipolar model introduced in [1], which is a natural model for ad-hoc and device-to-device (D2D) networks. The primary finding is that, with knowledge of channel state information between a receiver and its associated transmitter, by zero-forcing successive interference cancellation, and for appropriate antenna configurations, the ergodic spectral efficiency can be made to scale linearly with both 1) the…
This paper considers large random wireless networks where transmit-and-receive node pairs communicate within a certain range while sharing a common spectrum. By modeling the spatial locations of nodes based on stochastic geometry, analytical expressions for the ergodic spectral efficiency of a typical node pair are derived as a function of the channel state information available at a receiver (CSIR) in terms of relevant system parameters: the density of communication links, the number of receive antennas, the path loss exponent, and the operating signal-to-noise ratio. One key finding is that …
OFDM Enabled Over-the-Air Computation Systems with Two-Dimensional Fluid Antennas
School of Electronics and Information Technology, Sun Yat-sen University（中山大学电子与信息工程学院）；School of Computer Science and Engineering, Sun Yat-sen University（中山大学计算机科学与工程学院）
Fluid-Antenna-Assisted Distributed Joint Decoding for Cell-Free Massive MIMO Unsourced Random Access
Southeast University（东南大学）；National Mobile Communications Research Laboratory, Frontiers Science Center for Mobile Information Communication and Security, Southeast University（国家移动通信重点实验室，移动信息与安全前沿科学中心，东南大学）；Purple Mountain Laboratories（紫金山实验室）
Group Relative Policy Optimization for Robust Blind Interference Alignment with Fluid Antennas
Harbin Institute of Technology, Shenzhen（哈尔滨工业大学（深圳））；Guangdong Provincial Key Laboratory of Aerospace Communication and Networking Technology, Harbin Institute of Technology, Shenzhen（广东省航天通信与网络技术重点实验室，哈尔滨工业大学（深圳））；Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences（中国科学院深圳先进技术研究院）；KeyLaboratory of Systems and Control, Institute of Systems Science, Academy of Mathematics and Systems Science (AMSS), Chinese Academy of Sciences (CAS)（中国科学院数学与系统科学研究院系统与控制重点实验室）；School of Information Science and Engineering, Southeast University（东南大学信息科学与工程学院）；Southern University of Science and Technology（南方科技大学）
Off-Grid Position Optimization under Mutual Coupling in Fluid Antenna Arrays
National Mobile Communications Research Laboratory, Frontiers Science Center for Mobile Information Communication and Security, Southeast University（东南大学国家移动通信重点实验室、移动通信与信息安全前沿科学中心）；Purple Mountain Laboratories（紫金山实验室）；Key Laboratory of Intelligent Support Technology for Complex Environments, Ministry of Education, Nanjing University of Information Science and Technology（南京信息工程大学教育部复杂环境智能支撑技术重点实验室）
Fluid Antennas Assisted RIS-NOMA Communication Networks
Beihang University（北京航空航天大学）；North China University of Water Resources and Electric Power（华北水利水电大学）；Manchester Metropolitan University（曼彻斯特城市大学）；Queen Mary University of London（伦敦玛丽女王大学）
In this paper, we present a novel framework that can be used to study the capacity and power scaling properties of linear multiple-input multiple-output (MIMO) $d\times d$ antenna amplify-and-forward (AF) relay networks. In particular, we model these networks as random dynamical systems (RDS) and calculate their $d$ Lyapunov exponents. Our analysis can be applied to systems with any per-hop channel fading distribution, although in this contribution we focus on Rayleigh fading. Our main results are twofold: 1) the total transmit power at the $n$th node will follow a deterministic trajectory thr…
Finite-blocklength Fluid Antenna Systems With Spatial Block-Correlation Channel Model
National Mobile Communications Research Laboratory, Southeast University（东南大学国家移动通信重点实验室）；School of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；Department of Electronic and Electrical Engineering, University College London（伦敦大学学院电子电气工程系）；Yonsei Frontier Lab., Yonsei University（延世大学延世前沿实验室）；Department of Signal Theory, Networking and Communications, University of Granada（格拉纳达大学信号理论与网络通信系）；Telecommunications Research Institute (TELMA), University of Malaga（马拉加大学电信研究所（TELMA））；School of Integrated Technology, Yonsei University（延世大学综合技术学院）
Secure Transmission for Fluid Antenna-Aided ISAC Systems
School of Information Science and Engineering, Shandong University（山东大学信息科学与工程学院）；Information Technology Service Center, People’s Court, Beijing（北京市人民法院信息技术服务中心）
Artificial Noise Versus Artificial Noise Elimination: Redefining Scaling Laws of Physical Layer Security
Nanyang Technological University（南洋理工大学）；University of Electronic Science and Technology of China（电子科技大学）；Khalifa University（哈利法大学）；Princeton University（普林斯顿大学）
Cramer-Rao Bounds for Activity Detection in Conventional and Fluid Antenna Systems
National Mobile Communications Research Laboratory, Southeast University（东南大学国家移动通信重点实验室）；School of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；Department of Electronic and Electrical Engineering, University College London（伦敦大学学院电子电气工程系）；Yonsei Frontier Lab., Yonsei University（延世大学延世前沿实验室）；School of Integrated Technology, Yonsei University（延世大学综合技术学院）
Fluid-Antenna-Aided Active User Detection With 1D-CNN Channel Reconstruction for Unsourced Random Access
National Mobile Communications Research Laboratory, Frontiers Science Center for Mobile Information Communication and Security, Southeast University（东南大学移动通信国家重点实验室、移动信息与安全前沿科学中心）；Purple Mountain Laboratories（紫金山实验室）；Key Laboratory of Intelligent Support Technology for Complex Environments, Ministry of Education, Nanjing University of Information Science and Technology（南京信息工程大学复杂环境智能支撑技术教育部重点实验室）；School of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）
Finite-Aperture Fluid Antenna Array Design: Analysis and Algorithm
National Mobile Communications Research Laboratory, Southeast University（东南大学国家移动通信重点实验室）；School of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；Department of Electronic and Electrical Engineering, University College London（伦敦大学学院电子电气工程系）；Department of Electronic Engineering, Kyung Hee University（庆熙大学电子工程系）；Department of Electronics and Information Convergence Engineering, Kyung Hee University（庆熙大学电子与信息融合工程系）；Kuang-Chi Science Limited（光启科学有限公司）
EM-Guided Graph Learning for Fluid Antenna Beamforming under Current-Domain Constraints
College of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；School of Cyber Science and Engineering, Southeast University（东南大学网络空间安全学院）；National Mobile Communications Research Laboratory, Southeast University（东南大学移动通信国家重点实验室）；Purple Mountain Laboratories（紫金山实验室）
National Mobile Communications Research Laboratory, Southeast University（东南大学国家移动通信实验室）；School of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；Department of Electronic and Electrical Engineering, University College London（伦敦大学学院电子电气工程系）；Department of Electronic Engineering, Kyung Hee University（庆熙大学电子工程系）；College of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；School of Information Engineering, Nanchang University（南昌大学信息工程学院）
On the Performance of Single/Dual Fluid Antenna Systems
Beijing Jiaotong University（北京交通大学）；Lancaster University（兰卡斯特大学）；The University of Hong Kong（香港大学）；Queen Mary University of London（伦敦大学玛丽女王学院）；Kyung Hee University（庆熙大学）
Indoor Fluid Antenna Systems Enabled by Layout-Specific Modeling and Group Relative Policy Optimization
Harbin Institute of Technology, Shenzhen（哈尔滨工业大学（深圳））；Southern University of Science and Technology（南方科技大学）；Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences（中国科学院深圳先进技术研究院）；Tsinghua University（清华大学）；Northeastern University（东北大学）；Southeast University（东南大学）；University College London（伦敦大学学院）；Yonsei University（延世大学）
Multiple-input multiple-output (MIMO) technology has significantly impacted wireless communication, by providing extraordinary performance gains. However, a minimum inter-antenna space constraint in MIMO systems does not allow its integration in devices with limited space. In this context, the concept of fluid antenna systems (FASs) appears to be a potent solution, where there is no such restriction. In this paper, we investigate the average level crossing rate (LCR) of such FASs. Specifically, we derive closed-form analytical expressions of the LCR of such systems and extensive Monte-Carlo si…
National Mobile Communications Research Laboratory, Southeast University（东南大学国家移动通信实验室）；School of Cyber Science and Engineering, Southeast University（东南大学网络空间安全学院）；Department of Electronic and Electrical Engineering, University College London（伦敦大学学院电子电气工程系）；Department of Electronic Engineering, Kyung Hee University（庆熙大学电子工程系）；Department of Electronics and Information Convergence Engineering, Kyung Hee University（庆熙大学电子与信息融合工程学院）
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 i…
MAGRPO: Accelerated MARL Training for Fluid Antenna-Assisted Wireless Network Optimization
Harbin Institute of Technology, Shenzhen（哈尔滨工业大学（深圳））；Guangdong Provincial Key Laboratory of Aerospace Communication and Networking Technology, Harbin Institute of Technology, Shenzhen（哈尔滨工业大学（深圳）航天通信与网络技术广东省重点实验室）；School of Information Science and Engineering, Southeast University（东南大学信息科学与工程学院）；Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences（中国科学院深圳先进技术研究院）；Southern University of Science and Technology（南方科技大学）
Peak Sidelobe Suppression in Planar Fluid Antenna Array
National Mobile Communications Research Laboratory, Frontiers Science Center for Mobile Information Communication and Security, Southeast University（东南大学移动通信国家重点实验室、移动信息与安全前沿科学中心）；Purple Mountain Laboratories（紫金山实验室）；School of Cyber Science and Engineering, Southeast University（东南大学网络空间安全学院）；College of Artificial Intelligence, Nanjing University of Information Science and Technology（南京信息工程大学人工智能学院）；Southeast Unversity（东南大学）
