Massive connectivity with ultra-low latency and high reliability necessitates fundamental advances in future communication networks operating under finite-blocklength (FBL) transmission. Fluid antenna systems (FAS) have emerged as a promising enabler, offering superior spectrum and energy efficiency in short-packet/FBL scenarios. In this work, by leveraging the simplicity and accuracy of block-correlation channel modeling, we rigorously bound the performance limits of FBL-FAS from a statistical perspective, focusing on two key performance metrics: block error rate (BLER) and outage probability (OP). Furthermore, we introduce a novel complex-integral simplification method based on Gauss-Laguerre quadrature, which achieves higher approximation accuracy compared to existing Taylor-expansion-based approaches. Numerical results validate the robustness of the proposed analysis and clearly demonstrate the superiority of FBL-FAS over conventional multiple-antenna systems with fixed antenna placement.

翻译：在有限块长传输条件下，实现超低时延与高可靠性的海量连接，对未来通信网络提出了根本性变革的需求。流体天线系统凭借其在短包/有限块长场景下卓越的频谱与能量效率，已成为一种极具前景的使能技术。本研究利用块相关信道模型兼具简洁性与准确性的优势，从统计角度严格推导了有限块长流体天线系统的性能界限，重点关注两个关键性能指标：块错误率与中断概率。此外，我们提出了一种基于高斯-拉盖尔积分的新型复积分简化方法，相较于现有基于泰勒展开的近似方法，该方法实现了更高的近似精度。数值结果验证了所提分析框架的鲁棒性，并清晰展示了有限块长流体天线系统相对于传统固定天线布局多天线系统的优越性。