Performance Analysis of Finite Blocklength Transmissions Over Wiretap Fading Channels: An Average Information Leakage Perspective

TL;DR

This paper investigates finite blocklength wireless transmissions' security over fading channels using average information leakage as a metric, providing analytical insights and optimization strategies for system reliability and secrecy.

Contribution

It introduces the average information leakage metric for finite blocklength physical-layer security analysis and proposes optimization methods for secrecy throughput under practical conditions.

Findings

Analytical expressions for average information leakage are validated through simulations.

Allowing small information leakage can significantly improve system reliability.

Optimized blocklength and artificial noise power allocation enhance secrecy throughput.

Abstract

Physical-layer security (PLS) is a promising technique to complement more traditional means of communication security in beyond-5G wireless networks. However, studies of PLS are often based on ideal assumptions such as infinite coding blocklengths or perfect knowledge of the wiretap link's channel state information (CSI). In this work, we study the performance of finite blocklength (FBL) transmissions using a new secrecy metric $\unicode{x2013}$ the average information leakage (AIL). We evaluate the exact and approximate AIL with Gaussian signaling and arbitrary fading channels, assuming that the eavesdropper's instantaneous CSI is unknown. We then conduct case studies that use artificial noise (AN) beamforming to analyze the AIL in both Rayleigh and Rician fading channels. The accuracy of the analytical expressions is verified through extensive simulations, and various insights regarding the impact of key system parameters on the AIL are obtained. Particularly, our results reveal that allowing a small level of AIL can potentially lead to significant reliability enhancements. To improve the system performance, we formulate and solve an average secrecy throughput (AST) optimization problem via both non-adaptive and adaptive design strategies. Our findings highlight the significance of blocklength design and AN power allocation, as well as the impact of their trade-off on the AST.