2024/06/04 by Ignacio Santamarı́a, Mohammad Soleymani, Santamaria, Ignacio +5 · 6 citations
Engineering · Mathematics · #Advanced MIMO Systems Optimization #Advanced Wireless Communication Technologies #Computer science #Diagonal #Energy Harvesting in Wireless Networks #FOS: Computer and information sciences #FOS: Electrical engineering #Geometry #Information Theory (cs.IT) #MIMO #Mathematical optimization #Mathematics #Maximization #Signal Processing (eess.SP) #Statistics #electronic engineering #information engineering
paper · pdf · doi:10.48550/arxiv.2406.02170
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2024/06/04 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
This paper addresses the problem of maximizing the capacity of a multiple-input multiple-output (MIMO) link assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS). We maximize the capacity by alternately optimizing the transmit covariance matrix, and the BD-RIS scattering matrix, which, according to network theory, should be unitary and symmetric. These constraints make the optimization of BD-RIS more challenging than that of diagonal RIS. To find a stationary point of the capacity we maximize a sequence of quadratic problems in the manifold of unitary matrices. This leads to an efficient algorithm that always improves the capacity obtained by a diagonal RIS. Through simulation examples, we study the capacity improvement provided by a passive BD-RIS architecture over the conventional RIS model in which the phase shift matrix is diagonal.