Dual RIS Configuration for Signal Enhancement in L-Shaped Corridors

This paper addresses the challenge of severe signal attenuation in indoor Non-Line-of-Sight (NLOS) environments, particularly in L-shaped corridors. The study introduces a novel configuration that utilizes dual Reflective Intelligent Surfaces (RISs) strategically placed on adjacent walls to enhance signal strength in shadowed areas. A simulation framework based on geometrical and physical optics was developed to evaluate the performance of this setup. The proposed approach exploits the well-defined geometry of the corridor to set up a lightweight and efficient ray tracing algorithm. The results show that a single RIS placed near a corner can significantly improve signal coverage in obstructed corridors, but can produce coverage gaps. Instead, the dual RIS configuration provides more uniform coverage and consistent signal levels throughout the area, demonstrating its potential for practical implementation in complex indoor environments.