FLEX: Joint UL/DL and QoS-Aware Scheduling for Dynamic TDD in Industrial 5G and Beyond
This addresses the problem of inefficient scheduling for industrial 5G deployments with dynamic traffic, offering an incremental improvement over static schedulers.
The paper tackled the challenge of dynamic asymmetric traffic demands in industrial 5G TDD networks by proposing FLEX, a QoS-aware scheduler that dynamically adjusts UL/DL ratios, achieving similar throughput to established schedulers while maintaining minimal latency overhead of less than 1 slot duration for deterministic traffic.
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.