The synergy of metasurface-based holographic surfaces (HoloS) and reconfigurable intelligent surfaces (RIS) is considered a key aspect for future communication networks. However, the optimization of dynamic metasurfaces requires the use of numerical algorithms, for example, based on the singular value decomposition (SVD) and gradient descent methods, which are usually computationally intensive, especially when the number of elements is large. In this paper, we analyze low complexity designs for RIS-aided HoloS communication systems, in which the configurations of the HoloS transmitter and the RIS are given in a closed-form expression. We consider implementations based on diagonal and non-diagonal RISs. Over line-of-sight channels, we show that the proposed schemes provide performance that is close to that offered by complex numerical methods.

翻译：基于超表面的全息表面与可重构智能表面的协同作用被视为未来通信网络的关键技术。然而，动态超表面的优化需要借助数值算法（例如基于奇异值分解与梯度下降的方法），这类算法通常计算强度高，尤其在元素数量较大时尤为显著。本文针对可重构智能表面辅助全息通信系统，分析了低复杂度设计方案，其中全息发射机与可重构智能表面的配置以闭式表达式给出。我们考虑了对角与非对角两种可重构智能表面实现方式。在视距信道条件下，研究表明所提方案可获得与复杂数值方法相近的性能。