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arXiv · 2307.09807

A Low-Complexity Beamforming Design for Beyond-Diagonal RIS aided Multi-User Networks

Tianyu Fang·Yijie Mao
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Abstract

Beyond-diagonal reconfigurable intelligent surface (BD-RIS) has been proposed recently as a novel and generalized RIS architecture that offers enhanced wave manipulation flexibility and large coverage expansion. However, the beyond-diagonal mathematical model in BD-RIS inevitably introduces additional optimization challenges in beamforming design. In this letter, we derive a closed-form solution for the BD-RIS passive beamforming matrix that maximizes the sum of the effective channel gains among users. We further propose a computationally efficient two-stage beamforming framework to jointly design the active beamforming at the base station and passive beamforming at the BD-RIS to enhance the sum-rate for a BD-RIS aided multi-user multi-antenna network.Numerical results show that our proposed algorithm achieves a higher sum-rate while requiring less computation time compared to state-of-the-art algorithms. The proposed algorithm paves the way for practical beamforming design in BD-RIS aided wireless networks.

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Tianyu Fang, Yijie Mao. 2023-12-26. A Low-Complexity Beamforming Design for Beyond-Diagonal RIS aided Multi-User Networks. https://arxiv.org/abs/2307.09807

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