Quality-of-control-driven uplink scheduling for networked control systems running over 5G communication networks

Abstract

The emerging 5G networks will enable control-oriented applications where sensors, actuators, processors and controllers are geographically distributed and wirelessly connected. One major challenge of networked control systems (NCSs) is how to guarantee the stability of all control loops in the presence of communication delay. Addressing this problem, the control community generally focuses on designing new controllers or adjusting the sensor's sampling period to adapt to the network. Alternatively, we address the problem from the communication perspective in this paper. To this end, we consider all control loops as network applications (i.e. keeping controllers, sensors and actuators unchanged), and develop a control-aware network scheduler to handle the control performance degradation caused by communication delay. We further investigate how to interpret the Quality-of-Control as a Quality-of-Service (QoS) measure to guide the scheduler design. The proposed QoS metric represents the instantaneous Linear Quadratic Gaussian (LQG) cost of a control system, which quantifies the energy deviation of the system to its optimal condition. By leveraging the proposed QoS metric, we develop a novel QoS-driven uplink scheduler. Simulation results confirm the efficiency of the proposed scheduler for networked control services.