A reconfigurable intelligent surface (RIS) can shape the wireless propagation channel by inducing controlled phase shift variations to the impinging signals. Multiple works have considered the use of RIS by time-varying configurations of reflection coefficients. In this work we use the RIS to control the channel coherence time and introduce a generalized discrete-time-varying channel model for RIS-aided systems. We characterize the temporal variation of channel correlation by assuming that a configuration of RIS' elements changes at every time step. The analysis converges to a randomized framework to control the channel coherence time by setting the number of RIS' elements and their phase shifts. The main result is a framework for a flexible block-fading model, where the number of samples within a coherence block can be dynamically adapted.
翻译:可重新配置的智能表面(RIS)可以通过诱导受控的相位转移变异到阻塞信号来影响无线传播频道。多部作品考虑了通过反射系数的时序配置来使用RIS。在这项工作中,我们利用RIS来控制频道的一致性时间,并为RIS辅助系统引入一个通用的离散-时间变异信道模式。我们通过假设RIS元素在每一个步骤上的变化配置来描述频道相关性的时间变异。分析汇集到一个随机化的框架来通过设定RIS元素的数量及其相位变换来控制频道的一致性时间。主要结果是一个灵活区块形状模型的框架,在这个框架中,一个一致性区块内的样品数量可以动态地调整。