Average Achievable Rate Analysis of Cell-Free Massive MIMO in the Finite Blocklength Regime with Imperfect CSI

2025-08-24

AI Summary

Modeling the average achievable rate of cell-free massive MIMO under finite blocklength and imperfect channel state information (CSI) remains challenging—particularly for ultra-reliable low-latency communication (uRLLC), where high-dimensional channel estimation is severely constrained. Method: This paper proposes the first analytical framework based on the Laplace domain, combining stochastic geometry, Laplace-domain transformation, and Monte Carlo simulation for rigorous validation. Contribution/Results: We derive the first closed-form expression for the average achievable rate under imperfect CSI, explicitly characterizing channel dispersion and capacity via the Laplace transform of large-scale fading. Theoretically, we prove that the cell-free (CF) architecture significantly mitigates performance degradation induced by CSI estimation errors. Numerical results demonstrate excellent agreement between analytical predictions and simulations, confirming the framework’s high accuracy and robustness under stringent uRLLC constraints.

Technology Category

• Planning, Routing, and Scheduling: Scheduling under Uncertainty
• Machine Learning: Calibration & Uncertainty Quantification
• Reasoning under Uncertainty: Stochastic Optimization

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Web performance, measurement, and characterization
• User Modeling, Personalization and Recommendation: Practical large-scale studies of user experience

Abstract

Acquiring perfect channel state information (CSI) introduces substantial challenges in cell-free massive MIMO (CF-mMIMO) systems, primarily due to the large dimensionality of channel parameters, especially under ultra-reliable low-latency communication (uRLLC) constraints. Furthermore, the impact of imperfect CSI on the average achievable rate within the finite blocklength regime remains largely unexplored. Motivated by this gap, this paper proposes a novel analytical framework that provides a closed-form expression for the average achievable rate with imperfect CSI in the Laplace domain. We demonstrate analytically that both the channel dispersion and the expected channel capacity can be expressed explicitly in terms of the Laplace transform of the large-scale fading component. Numerical simulations confirm that the derived expressions match closely with Monte Carlo simulations, verifying their accuracy. Furthermore, we theoretically show that although imperfect CSI degrades performance in the finite blocklength regime, the inherent characteristics of CF-mMIMO architecture effectively mitigates this loss.

Problem

• Analyzing average achievable rate with imperfect CSI
• Exploring finite blocklength regime impacts on performance
• Developing closed-form expressions for channel capacity

Innovation

• Closed-form rate expression in Laplace domain
• Explicit channel dispersion via Laplace transform
• CF-mMIMO architecture mitigates imperfect CSI loss