PhysFad: Physics-Based End-to-End Channel Modeling of RIS-Parametrized Environments With Adjustable Fading

Metasurface‐Programmable Wireless Network‐On‐Chip

“…The standard deviation σ of these complex‐valued channels across different configurations is a reliable metric of the ability of the RIS to manipulate these channels in the considered setting. [ 14,23,70 ] The ability of our RIS to modulate frequencies across the entire considered 55 − 65 GHz band is now evident in Figure 3c,d.…”

“…[ 84 ] Here, the alternative route of using the simple iterative Algorithm 1 similar to those used, for example, in refs. [29, 70], was chosen.…”

“…More recently, the concept of RIS‐empowered “over‐the‐air equalization” has also been explored based on channel models. [ 66–70 ] However, refs. [67, 69] consider a simple free‐space two‐path channel, and the remaining works, with the exception of ref.…”

“…[67, 69] consider a simple free‐space two‐path channel, and the remaining works, with the exception of ref. [70], utilize channel models that are not compatible with all aspects of wave physics. Specifically, they appear to violate causality, to neglect the long‐range mescoscopic correlations at the origin of the non ‐linear RIS‐parametrization of the fading wireless channels [ 70–72 ] , and to ignore the frequency selectivity of the RIS element as well as the intertwinement of its amplitude and phase response.…”

“…[70], utilize channel models that are not compatible with all aspects of wave physics. Specifically, they appear to violate causality, to neglect the long‐range mescoscopic correlations at the origin of the non ‐linear RIS‐parametrization of the fading wireless channels [ 70–72 ] , and to ignore the frequency selectivity of the RIS element as well as the intertwinement of its amplitude and phase response. To ensure the reliability of the present work, we use full‐wave simulations which are computationally costly but guaranteed to respect wave physics.…”