FLEX: Joint UL/DL and QoS-Aware Scheduling for Dynamic TDD in Industrial 5G and Beyond

TL;DR

FLEX is a novel QoS-aware scheduler for industrial 5G TDD networks that dynamically adjusts UL/DL ratios based on traffic demands, ensuring QoS compliance and low latency.

Contribution

It introduces a dynamic, QoS-aware scheduling algorithm that adapts UL/DL ratios in industrial 5G TDD, leveraging buffer state estimation and traffic prediction.

Findings

FLEX achieves throughput comparable to existing schedulers.

FLEX enforces QoS priorities effectively in both traffic directions.

FLEX maintains latency overhead below 1 slot duration for deterministic traffic.

Abstract

Industrial 5G deployments using Time Division Duplex (TDD) networks face a critical challenge: existing schedulers rely on static configuration of Uplink (UL) to Downlink (DL) resource ratios, failing to adapt to dynamic asymmetric traffic demands. This limitation is particularly problematic in Industry 4.0 scenarios where traffic patterns exhibit significant asymmetry between directions and heterogeneous Quality of Service (QoS) requirements. We present FLEX, a novel QoS-aware scheduler that dynamically adjusts the UL/DL ratio in flexible TDD slots while respecting diverse QoS requirements. FLEX introduces DL buffer state estimation to prevent starvation of high-priority DL traffic, exploiting the deterministic nature of industrial traffic patterns for accurate predictions. Through extensive simulations of industrial scenarios using 5G LENA and ns-3, we demonstrate that FLEX achieves similar throughput compared to established scheduling while correctly enforcing QoS priorities in both traffic directions. For deterministic traffic patterns, FLEX maintains minimal latency overhead (less than 1 slot duration), making it particularly suitable for industrial automation applications.