2024/04/01 by Özlem Tuğfe Demir, Emil Björnson, Demir, Özlem Tuğfe +1 · 4 citations
Computer Science · Engineering · #Antenna Design and Optimization #FOS: Computer and information sciences #FOS: Electrical engineering #Information Theory (cs.IT) #Satellite Communication Systems #Signal Processing (eess.SP) #Wireless Communication Networks Research #electronic engineering #information engineering
paper · pdf · doi:10.48550/arxiv.2404.00982
openalex publication_date 2024/04/01 · openalex created_date 2024/04/03 · openalex updated_date 2026/07/28
Following the promising beamforming gains offered by reconfigurable intelligent surfaces (RISs), a new hardware architecture, known as beyond diagonal RIS (BD-RIS), has recently been proposed. This architecture enables controllable signal flows between the RIS elements, thereby providing greater design flexibility. However, the physics-imposed symmetry and orthogonality conditions on the non-diagonal reflection matrix make the design challenging. In this letter, we analyze how a BD-RIS can improve a wideband channel, starting from fundamental principles and deriving the capacity. Our analysis considers the effects of various channel taps and their frequency-domain characteristics. We introduce a new algorithm designed to optimize the configuration of the BD-RIS to maximize wideband capacity. The proposed algorithm has better performance than the benchmarks. A BD-RIS is beneficial compared to a conventional RIS in the absence of static path or when the Rician κ-factor is smaller than 10.