Optimizing Rate-CRB Performance for Beyond Diagonal Reconfigurable Intelligent Surface Enabled ISAC

Xiaoqi Zhang; Liang Liu; Shuowen Zhang; Weifeng Zhu; Haijun Zhang

doi:10.1109/LCOMM.2025.3599597

Optimizing Rate-CRB Performance for Beyond Diagonal Reconfigurable Intelligent Surface Enabled ISAC

Xiaoqi Zhang, Liang Liu, Shuowen Zhang, Weifeng Zhu, Haijun Zhang

Research output: Journal article publication › Journal article › Academic research › peer-review

Abstract

This letter considers a beyond diagonal reconfigurable intelligent surface (BD-RIS) aided integrated sensing and communication (ISAC) system, where the BD-RIS can help a multi-antenna base station (BS) serve multiple user equipments (UEs) and localize a target simultaneously. We formulate an optimization problem that designs the BS beamforming matrix and the BD-RIS scattering matrix to maximize UEs’ sum rate subject to a localization Cramér-Rao bound (CRB) constraint and an additional unitary matrix constraint for the scattering matrix. Because unitary matrices form a manifold, our problem belongs to constrained manifold optimization. This letter proposes a log-barrier based Riemannian steepest ascent method to solve this problem effectively. Numerical results verify the effectiveness of our algorithm and the performance gain of the BD-RIS aided ISAC systems over the conventional RIS aided ISAC systems.

Original language	English
Article number	11127049
Pages (from-to)	1-5
Number of pages	5
Journal	IEEE Communications Letters
DOIs	https://doi.org/10.1109/LCOMM.2025.3599597
Publication status	Published - Aug 2025

Keywords

Beyond diagonal reconfigurable intelligent surface (BD-RIS)
Cramér-Rao bound (CRB)
integrated sensing and communication (ISAC)
Riemannian steepest ascent method

ASJC Scopus subject areas

Modelling and Simulation
Computer Science Applications
Electrical and Electronic Engineering

More information

10.1109/LCOMM.2025.3599597

Cite this

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title = "Optimizing Rate-CRB Performance for Beyond Diagonal Reconfigurable Intelligent Surface Enabled ISAC",

abstract = "This letter considers a beyond diagonal reconfigurable intelligent surface (BD-RIS) aided integrated sensing and communication (ISAC) system, where the BD-RIS can help a multi-antenna base station (BS) serve multiple user equipments (UEs) and localize a target simultaneously. We formulate an optimization problem that designs the BS beamforming matrix and the BD-RIS scattering matrix to maximize UEs{\textquoteright} sum rate subject to a localization Cram{\'e}r-Rao bound (CRB) constraint and an additional unitary matrix constraint for the scattering matrix. Because unitary matrices form a manifold, our problem belongs to constrained manifold optimization. This letter proposes a log-barrier based Riemannian steepest ascent method to solve this problem effectively. Numerical results verify the effectiveness of our algorithm and the performance gain of the BD-RIS aided ISAC systems over the conventional RIS aided ISAC systems.",

keywords = "Beyond diagonal reconfigurable intelligent surface (BD-RIS), Cram{\'e}r-Rao bound (CRB), integrated sensing and communication (ISAC), Riemannian steepest ascent method",

author = "Xiaoqi Zhang and Liang Liu and Shuowen Zhang and Weifeng Zhu and Haijun Zhang",

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doi = "10.1109/LCOMM.2025.3599597",

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AU - Zhang, Xiaoqi

AU - Liu, Liang

AU - Zhang, Shuowen

AU - Zhu, Weifeng

AU - Zhang, Haijun

PY - 2025/8

Y1 - 2025/8

N2 - This letter considers a beyond diagonal reconfigurable intelligent surface (BD-RIS) aided integrated sensing and communication (ISAC) system, where the BD-RIS can help a multi-antenna base station (BS) serve multiple user equipments (UEs) and localize a target simultaneously. We formulate an optimization problem that designs the BS beamforming matrix and the BD-RIS scattering matrix to maximize UEs’ sum rate subject to a localization Cramér-Rao bound (CRB) constraint and an additional unitary matrix constraint for the scattering matrix. Because unitary matrices form a manifold, our problem belongs to constrained manifold optimization. This letter proposes a log-barrier based Riemannian steepest ascent method to solve this problem effectively. Numerical results verify the effectiveness of our algorithm and the performance gain of the BD-RIS aided ISAC systems over the conventional RIS aided ISAC systems.

AB - This letter considers a beyond diagonal reconfigurable intelligent surface (BD-RIS) aided integrated sensing and communication (ISAC) system, where the BD-RIS can help a multi-antenna base station (BS) serve multiple user equipments (UEs) and localize a target simultaneously. We formulate an optimization problem that designs the BS beamforming matrix and the BD-RIS scattering matrix to maximize UEs’ sum rate subject to a localization Cramér-Rao bound (CRB) constraint and an additional unitary matrix constraint for the scattering matrix. Because unitary matrices form a manifold, our problem belongs to constrained manifold optimization. This letter proposes a log-barrier based Riemannian steepest ascent method to solve this problem effectively. Numerical results verify the effectiveness of our algorithm and the performance gain of the BD-RIS aided ISAC systems over the conventional RIS aided ISAC systems.

KW - Beyond diagonal reconfigurable intelligent surface (BD-RIS)

KW - Cramér-Rao bound (CRB)

KW - integrated sensing and communication (ISAC)

KW - Riemannian steepest ascent method

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DO - 10.1109/LCOMM.2025.3599597

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JO - IEEE Communications Letters

JF - IEEE Communications Letters

M1 - 11127049

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Optimizing Rate-CRB Performance for Beyond Diagonal Reconfigurable Intelligent Surface Enabled ISAC

Abstract

Keywords

ASJC Scopus subject areas

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