Electromagnetically-Consistent Modeling and Optimization of Mutual Coupling in RIS-Assisted Multi-User MIMO Communication Systems

作     者：Wijekoon, Dilki Mezghani, Amine Alexandropoulos, George C. Hossain, Ekram 

作者机构：Department of Electrical and Computer Engineering University of Manitoba Winnipeg Canada Department of Informatics and Telecommunications National and Kapodistrian University of Athens Greece 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2024年

核心收录：

主　　题：MIMO systems 

摘      要：Mutual Coupling (MC) is an unavoidable feature in Reconfigurable Intelligent Surfaces (RISs) with sub-wavelength inter-element spacing. Its inherent presence naturally leads to non-local RIS structures, which can be efficiently described via non-diagonal phase shift matrices. In this paper, we focus on optimizing MC in RIS-assisted multi-user MIMO wireless communication systems. We particularly formulate a novel problem to jointly optimize active and passive beamforming as well as MC in a physically consistent manner. To characterize MC, we deploy scattering parameters and propose a novel approach to optimize them through an offline optimization method, rather than optimizing MC on the fly. Our numerical results showcase that the system performance increases with the proposed MC optimization, and this improvement is achievable without the need for optimizing MC on-the-fly, which can be rather cumbersome. © 2024, CC BY-NC-ND.