Reconfigurable Intelligent Surface Optimized Over-The-Air Control of Networked Dynamic Systems

Recently proposed over-the-air (OTA) controllers enable spectrum-efficient data fusion and control of networked dynamical systems such as swarm of drones and smart-grids. By properly tuning wireless channels, control signals can be formed via electromagnetic superposition of nodes’ states transmitted on the same frequency, and received at the controller. However, the challenge of current OTA controllers lies in the insufficient optimization variables to compensate wireless channels for OTA control objectives. In this work, we leverage the massive channel tuning elements of a reconfigurable intelligent surface (RIS) to design a RIS optimized OTA controller for networked dynamical systems. We first formulate the RIS-assisted OTA control objective function and a non-convex minimax eigenvalue optimization problem. Then, an quadratic upper-bound of the maximum eigenvalue is found to approximate the original optimization problem into a convex form. A smart-grid case-study is explored to validate our proposed RIS-OTA controller. Simulation results illustrate better control performance of our proposed RIS-OTA controller than existing transmitter power allocation based OTA controller, showing the promising potentials of RIS-optimized OTA controller in practical networked dynamical systems.