Reconfigurable Intelligent Surface (RIS) Assisted Wireless Coverage Extension: RIS Orientation and Location Optimization

Recently, reconfigurable intelligent surfaces (RIS) have attracted a lot of attention due to their capability of extending cell coverage by reflecting signals toward the receiver. In this letter, we analyze the coverage of a downlink RIS-assisted network with one base station (BS) and one user equipment (UE). Since the RIS orientation and the horizontal distance between the RIS and the BS have a significant influence on the cell coverage, we formulate an RIS placement optimization problem to maximize the cell coverage by optimizing the RIS orientation and horizontal distance. To solve the formulated problem, a coverage maximization algorithm (CMA) is proposed, where a closed-form optimal RIS orientation is obtained. Numerical results verify our analysis.

I. Introduction

Reconfigurable intelligent surfaces (RIS) are an emerging wireless communication technology and is capable of shaping the propagation environment into a desired form [1], [2]. The RIS is inlaid with a large number of reflecting elements whose electromagnetic (EM) response can be tuned dynamically with onboard positive-intrinsic-negative (PIN) diodes [3]. By controlling the EM responses of the elements, the received signal strength can be optimized [4].