The demand for unprecedented performance in the upcoming 6G wireless networks is fomenting the research on THz communications empowered by Reconfigurable Inteligent Surfaces (RISs). A wide range of use cases have been proposed, most of them, assuming high-level RIS models that overlook some of the hardware impairments that this technology faces. The expectation is that the emergent reconfigurable THz technologies will eventually overcome its current limitations. This disassociation from the hardware may mask nonphysical assumptions, perceived as hardware limitations. In this paper, a top-down approach bounded by physical constraints is presented, distilling from system-level specifications, hardware requirements, and upper bounds for the RIS-aided system performance. We consider D-band indoor and outdoor scenarios where a more realistic assessment of the state-of-the-art solution can be made. The goal is to highlight the intricacies of the design procedure based on sound assumptions for the RIS performance. For a given signal range and angular coverage, we quantify the required RIS size, number of switching elements, and maximum achievable bandwidth and capacity.

翻译：即将到来的6G无线网络对前所未有性能的需求，正推动着由可重构智能表面（RISs）赋能的太赫兹通信研究。尽管已有广泛的应用场景被提出，但其中绝大多数均基于对RIS的高层级模型假设，忽视了该技术面临的某些硬件损伤。人们期望新兴的可重构太赫兹技术能最终克服其当前局限。这种与硬件的脱节可能掩盖非物理性假设，而将其误判为硬件限制。本文提出了一种受物理约束约束的自顶向下方法，从系统级规范、硬件需求及RIS辅助系统性能的上界出发进行提炼。我们考虑了D波段室内与室外场景，这些场景能够对现有技术方案进行更实际的评估。其目标在于基于合理的RIS性能假设，突出设计过程的复杂性。针对给定的信号范围与角度覆盖，我们量化了所需的RIS尺寸、切换元件数量以及可实现的最大带宽与容量。