A Universal Block Error Rate Bound for Fluid Antenna Systems

TL;DR

This paper derives a universal block error rate bound for fluid antenna systems, providing a practical performance benchmark that applies across different architectures and scenarios, enhancing analytical and empirical understanding.

Contribution

It introduces a general, computable BLER bound for finite blocklength fluid antenna systems, applicable with or without explicit statistical models, filling a key gap in performance analysis.

Findings

BLER bound aligns well with empirical results

The bound is simple, accurate, and universally applicable

Applicable to both model-aware and model-free scenarios

Abstract

Fluid antenna systems (FASs) offer genuine simplicity for communication network design by eliminating expensive hardware overhead and reducing the complexity of access protocol architectures. Through the discovery of significant spatial diversity within a compact antenna space, FASs enable the implementation of reconfigurable-antenna-based architectures. However, current state-of-the-art studies rarely investigate the impact of finite blocklength constraints on FAS-based designs, leaving a gap in both analytical modeling and the establishment of a solid, universally applicable performance metric for finite blocklength fluid antenna systems (FBL-FAS). In this work, we focus on the study of FBL-FAS and, more importantly, derive a block error rate (BLER) bound that serves as a general and practical performance benchmark across various FAS architectures. The proposed BLER bound is computable both with and without an explicit statistical model, meaning that the BLER performance can be characterized analytically or empirically under model-aware or model-free system scenarios. Moreover, when the statistical model is known, the analytical results derived from the proposed BLER bound exhibit strong alignment with the empirical findings, demonstrating the remarkable simplicity, accuracy, and universality of the proposed BLER bound.