NeTS: Small: (SRI)2: Software-defined STAR-RIS for Robust and Intelligent Internet of Things

A Reconfigurable Intelligent Surface (RIS) is a programmable structure that can control the reflection of electromagnetic (EM) waves such as 5G and 6G cellular transmissions. Simultaneous Transmission and Reflection Reconfigurable Intelligent Surfaces (STAR-RIS) can simultaneously program the transmitted and reflected EM waves. Most existing RIS panels are passive or nearly passive, limited to reflection only, and are constrained by their low power for short-range communication. Current STAR-RIS designs struggle to minimize the power required to direct incoming waves in any direction while maintaining or increasing reflection gain, due to a lack of individually controllable elements that can switch flexibly between passive and active modes. This project aims to develop a metasurface-based hybrid STAR-RIS panel capable of digitally adjusting both the amplitude and phase of the reflection and transmission coefficients of EM waves. The elements on this new panel will be programmed to function as passive or active, enabling simultaneous reflection and transmission across frequencies ranging from the sub-6 GHz band to the millimeter-wave regime. The outcome of this project will enhance the functionality of RIS, supporting the resilient operation of the 5G and future wireless networks, which are crucial for the widespread deployment of Internet of Things (IoT) devices. The objective of this project is to design STAR-RIS to support the resilient operation of massive IoT networks that are integral to 5G/6G wireless communication systems and beyond. The STAR-RIS panel elements can be passive, active, and dynamically programmable, allowing them to switch between passive and active modes as needed. A nearly passive RIS panel will first be developed on a standard printed circuit board (PCB). An active RIS panel will then be developed using patch antenna arrays with tunnel diode amplifiers and varactor diodes. Additionally, both the nearly passive RIS and active RIS will be optimized to have a hybrid fully dynamic STAR-RIS panel by incorporating an array of piezoelectric plates on a separated PCB. The RIS panels developed at each step will be characterized for reflection coefficients. The advancement of the proposed STAR-RIS will enhance the adaptability of RIS panels through dynamic programming, reducing the power necessary for modulating both amplitude and phase in wireless communication. In addition to supporting extensions to 5G and 6G services, the broader impacts of this project encompass hosting the annual “ISU-Wireless Communication Devices and Systems Day”, incorporating new findings into both graduate and undergraduate curricula, engaging undergraduate students through collaboration with existing programs, and offering opportunities for senior design projects focused on wireless communication systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.