Riemannian optimization on the manifold of unitary and symmetric matrices with application to BD-RIS-assisted systems

Fuente: arXiv
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Autores principales: Santamaria, Ignacio, Soleymani, Mohammad, Jorswieck, Eduard, Gutierrez, Jesus, Beltran, Carlos
Formato: Preprint
Publicado: 2026
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author Santamaria, Ignacio
Soleymani, Mohammad
Jorswieck, Eduard
Gutierrez, Jesus
Beltran, Carlos
author_facet Santamaria, Ignacio
Soleymani, Mohammad
Jorswieck, Eduard
Gutierrez, Jesus
Beltran, Carlos
contents In this paper, we rigorously characterize for the first time the manifold of unitary and symmetric matrices, deriving its tangent space and its geodesics. The resulting parameterization of the geodesics (through a real and symmetric matrix) allows us to derive a new Riemannian manifold optimization (MO) algorithm whose most remarkable feature is that it does not need to set any adaptation parameter. We apply the proposed MO algorithm to maximize the achievable rate in a multiple-input multiple-output (MIMO) system assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS), illustrating the method's performance through simulations. The MO algorithm achieves a significant reduction in computational cost compared to previous alternatives based on Takagi decomposition, while retaining global convergence to a stationary point of the cost function.
format Preprint
id arxiv_https___arxiv_org_abs_2601_13877
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Riemannian optimization on the manifold of unitary and symmetric matrices with application to BD-RIS-assisted systems
Santamaria, Ignacio
Soleymani, Mohammad
Jorswieck, Eduard
Gutierrez, Jesus
Beltran, Carlos
Signal Processing
In this paper, we rigorously characterize for the first time the manifold of unitary and symmetric matrices, deriving its tangent space and its geodesics. The resulting parameterization of the geodesics (through a real and symmetric matrix) allows us to derive a new Riemannian manifold optimization (MO) algorithm whose most remarkable feature is that it does not need to set any adaptation parameter. We apply the proposed MO algorithm to maximize the achievable rate in a multiple-input multiple-output (MIMO) system assisted by a beyond-diagonal reconfigurable intelligent surface (BD-RIS), illustrating the method's performance through simulations. The MO algorithm achieves a significant reduction in computational cost compared to previous alternatives based on Takagi decomposition, while retaining global convergence to a stationary point of the cost function.
title Riemannian optimization on the manifold of unitary and symmetric matrices with application to BD-RIS-assisted systems
topic Signal Processing
url https://arxiv.org/abs/2601.13877