Reliability-Latency-Rate Tradeoff in Low-Latency Communications with Finite-Blocklength Coding

TL;DR

This paper explores the fundamental tradeoffs between reliability, latency, and service rate in low-latency wireless communications using finite-blocklength coding, providing analytical tools and insights for system optimization.

Contribution

It introduces a novel framework based on effective capacity to characterize the reliability-latency-rate tradeoff in low-latency systems with finite-blocklength coding, including asymptotic analysis and throughput optimization.

Findings

Characterizes the reliability-latency-rate tradeoff using gain-conservation equations.

Provides asymptotic analysis in high SNR regimes for AWGN and Nakagami-m channels.

Derives a closed-form EC-approximation for throughput optimization.

Abstract

Low-latency communication plays an increasingly important role in delay-sensitive applications by ensuring the real-time information exchange. However, due to the constraint on the maximum instantaneous power, guaranteeing bounded latency is challenging. In this paper, we investigate the reliability-latency-rate tradeoff in low-latency communication systems with finite-blocklength coding (FBC). Specifically, we are interested in the fundamental tradeoff between error probability, delay-violation probability (DVP), and service rate. Based on the effective capacity (EC), we present the gain-conservation equations to characterize the reliability-latency-rate tradeoffs in low-latency communication systems. In particular, we investigate the low-latency transmissions over an additive white Gaussian noise (AWGN) channel and a Nakagami-$m$ fading channel. By defining the service rate gain, reliability gain, and real-time gain, we conduct an asymptotic analysis to reveal the fundamental reliability-latency-rate tradeoff of ultra-reliable and low-latency communications in the high signal-to-noise-ratio (SNR) regime. To analytically evaluate and optimize the quality-of-service-constrained throughput of low-latency communication systems adopting FBC, an EC-approximation method is conceived to derive the closed-form expression of that throughput. Our results may offer some insights into the efficient scheduling of low-latency wireless communications, in which statistical latency and reliability metrics are crucial.