Beyond diagonal reconfigurable intelligent surface (BD-RIS) is a novel branch of RIS which breaks through the limitation of traditional RIS with diagonal scattering matrices. However, the existing research focuses on BD-RIS with fixed architectures regardless of channel state information (CSI), which limit the achievable performance of BD-RIS. To solve this issue, in this paper, we propose a novel dynamically group-connected BD-RIS based on a dynamic grouping strategy. Specifically, RIS antennas are dynamically divided into several subsets adapting to the CSI, yielding a permuted block-diagonal scattering matrix. To verify the effectiveness of the proposed dynamically group-connected BD-RIS, we propose an efficient algorithm to optimize the BD-RIS with dynamic grouping for a BD-RIS-assisted multi-user multiple-input single-output system. Simulation results show that the proposed dynamically group-connected architecture outperforms fixed group-connected architectures.

翻译：超越对角线可重构智能表面（BD-RIS）是RIS的一个新兴分支，突破了传统RIS对角线散射矩阵的限制。然而，现有研究主要关注基于固定架构的BD-RIS，而未考虑信道状态信息（CSI），这限制了BD-RIS的性能。为解决此问题，本文提出一种基于动态分组策略的新型动态组连接BD-RIS。具体而言，RIS天线根据CSI自适应地划分为若干子集，生成置换块对角散射矩阵。为验证所提动态组连接BD-RIS的有效性，我们针对BD-RIS辅助的多用户多输入单输出系统，提出了一种高效算法以优化动态分组下的BD-RIS。仿真结果表明，所提动态组连接架构优于固定组连接架构。