Modular Reconfigurable Intelligent Surfaces: Towards an Application-Adaptive Implementation

Abstract:
Within the ongoing development of the Sixth Generation (6G) wireless communications, design criteria have emerged aiming to deliver more intelligent, complete, and secure interconnections with higher data rates, more throughput, and lower latency. Reconfigurable Intelligent Surfaces (RISs), an array of elements capable of manipulating the reflective properties of propagating waves, are said to be one of the key enabling technologies to meet the expectations set in 6G. The research for the design and deployment of RIS systems has been based on specific use cases that consider the physical characteristics of the signals, the transmission medium, the frequency, and the power. Additionally, the number of elements varies depending on the application requirements. Therefore, the focus of this work is to propose a step towards a modular framework, where a pre-set number of cells is designed, and based on the application requirements, the defined modules are connected or disconnected to the ensemble. This results in a flexible RIS system offering greater versatility to different scenarios, by allowing to scale up or down a certain number of RIS elements. Moreover, in contrast to the rigidity of a standard RIS system, it is possible to scale the system cost-effectively. The proposal includes an initial approach to the management of RIS units through control boards that can handle the addition or removal of RIS subsystems according to the application needs. Notwithstanding the advantages that a modular RIS system can offer in terms of adaptability to different scenarios or in maintainability of the system, this approach also brings challenges to be explored, for instance, the coordination of the individual elements and the power management.