Control-Communication Co-Design for Cloud–Fog Automation Over 5G–TSN: A Coupling Loop Method Under Network Uncertainty

The cloud–fog automation (CFA) paradigm accelerates Industry 4.0 by enabling fully automated industrial systems through interconnected wired and wireless devices. However, dynamic uncertainties such as environment-induced network delays and disturbances challenge the stability and efficiency of these systems. To address these issues, this paper proposes a control–communication co-design framework named C3L (Control– Communication Coupling Loop), which integrates 5G and Time-Sensitive Networking (TSN) to coordinate transmission and control across cloud and fog layers. A hierarchical control strategy is introduced based on a delay threshold derived from Linear Matrix Inequality (LMI) analysis, enabling dynamic selection between cloud and fog control units for both stability and responsiveness. To ensure timely and reliable control input delivery under uncertain networks, we develop a deterministic transmission mechanism centered on a novel metric, Packet Loss Tolerance (PLT), which quantifies how many consecutive losses the system can endure while maintaining stability. Additionally, a new optimization criterion, Pareto Deviation Value (PDV), is proposed to avoid combining control and communication costs with incompatible physical units. Simulation results demonstrate that the proposed method enhances control robustness and communication efficiency in complex industrial networks.