Randomized Control of Wireless Temporal Coherence via Reconfigurable Intelligent Surface

TL;DR

This paper introduces a novel framework for controlling wireless channel coherence time using reconfigurable intelligent surfaces (RIS), enabling dynamic adaptation of the block-fading model for improved wireless communication performance.

Contribution

It presents a generalized discrete-time channel model for RIS-aided systems and a randomized approach to adjust channel coherence time by configuring RIS elements and phase shifts.

Findings

Framework for flexible block-fading model

Dynamic adaptation of coherence time based on RIS configuration

Convergence to a randomized control scheme

Abstract

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.