Implementation of Embedded Controllers for Scalable RIS Assemblies

Abstract

This dissertation explores the development of a control system for RISs using embedded microcontrollers. RISs are programmable surfaces composed of multiple elements capable of manipulating electromagnetic waves in a controlled manner, allowing them to reflect, redirect, or focus signals in a desired direction.

This work focuses on developing a four-tile RIS setup control system on two different embedded platforms, the ESP32 and the Pico-Ice. The software was implemented on both controllers to allow real-time configuration of a RIS system. These controllers can perform a determined action based on a series of high-level commands that are sent from a central controller using serial communication. Namely, the software enables the control of each tile or, alternatively, it can control the four tiles simultaneously.

After the implementation, the overall performance of the control software was tested and optimized. Improvements, such as trigonometric lookup tables and precomputed conversion constants, were implemented to reduce computation time. The optimized versions were evaluated across several tile sizes, and a comparative analysis between the two microcontrollers was performed.

Results show that the ESP32 achieved significantly lower execution times than the Pico-Ice when running the beamforming algorithm. However, because the Pico-Ice also has a built-in FPGA, it could later be explored for offloading some calculations to further decrease computation time.

This work demonstrates that developing an effective RIS control system is feasible on low-power microcontrollers and lays a foundation that can be built upon to introduce further enhancements.