Real-Time Wireless Networked Control Systems with Coding-Free Data Transmission

Wireless networked control systems for Industrial Internet of Things (IIoT) require low latency communication techniques. In this paper, we investigate a coding-free control method to achieve ultra-low latency communications in single-controller-multi-plant networked control systems. We formulate a power allocation problem to optimize the sum cost functions of multiple plants, subject to the plant stabilization condition and the controller's power limit. Although the optimization problem is a non-convex one, we derive a closed-form solution, which indicates that the optimal power allocation policy for stabilizing the plants with different channel conditions is reminiscent of the channel-inversion policy. Also, we numerically compare the performance of the proposed coding-free control method and the conventional coding-based control methods in terms of the cost function of a plant, which shows that the coding-free method is superior in a practical range of SNRs.