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被认为是未来通信网络的关键方面。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和梯度下降的方法，这些方法通常计算密集，尤其在元素数量庞大时更为突出。本文分析了RIS辅助全息通信系统的低复杂度设计方案，其中全息发射机和RIS的配置以闭式表达式给出。我们考虑了基于对角和非对角RIS的实现方式。在视线信道条件下，我们证明所提出的方案性能接近复杂数值方法所提供的性能。