On the Performance of Single/Dual Fluid Antenna Systems
2026-05-25 • Information Theory
Information Theory
AI summaryⓘ
The authors study fluid antenna systems, which are antennas that can change the position of their elements to better catch signals. They look at two setups: one where a multi-antenna transmitter talks to a receiver with a fluid antenna, and another where both transmitter and receiver have fluid antennas. They calculate exact and approximate formulas to understand how often the signal drops out (outage probability) and how well these systems perform. They find that having more antenna ports and less correlation between them improves performance, and in good signal conditions, the dual fluid antenna setup does better than the single fluid antenna one.
Fluid Antenna Systems (FAS)Spatial DiversityRayleigh FadingMultiple-Input Single-Output (MISO)Outage ProbabilityPort CorrelationDiversity OrderSignal-to-Noise Ratio (SNR)Reconfigurable Antennas
Authors
Jiangsheng Huangfu, Zhengyu Song, Tianwei Hou, Anna Li, Yuanwei Liu, Arumugam Nallanathan
Abstract
The emerging technology of fluid antenna systems (FASs) represents a promising next-generation reconfigurable antenna solution, capable of exploiting the full spatial diversity within a predefined space by finely reconfiguring the positions of radiating elements. In this paper, the performance of FAS over spatially correlated Rayleigh fading channels is investigated for two distinct scenarios: a multiple-input single-output (MISO) configuration, where a receiver with a single-antenna FAS is served by a multi-antenna transmitter (MISO-FAS), and a single-input single-output setup where single-antenna FASs are equipped at both the transmitter and receiver (Dual-FAS). Exact expressions and closed-form approximations for the outage probability (OP) of both the MISO-FAS and Dual-FAS models are derived as the core contributions of this work. To provide deeper insights into system performance, the diversity orders for each model are also derived and analyzed. Analytical results demonstrate that increasing the number of ports significantly enhances system performance. The theoretical analysis is corroborated by key findings from our simulations, demonstrating that: $i$) Both the MISO-FAS and Dual-FAS models achieve considerable performance gains as the number of ports is increased; $ii$) System performance for both configurations is inversely related to the level of port correlation; lower correlation leads to better performance; $iii$) In the high signal-to-noise ratio regime, the Dual-FAS model surpasses the performance of the MISO-FAS model.