Single-Reflection Point Distribution Estimation for IRS Placement Problem

Intelligent reflecting surface (IRS) has attracted a lot of attention in terms of expanding the coverage of base stations (BSs) in high frequency bands such as millimeter-wave and terahertz bands. Owing to the ability to dynamically control the amplitudes and phases of the reflected signals, IRSs can establish virtual line-of-sight (LOS) paths on non-line-of-sight (NLOS) paths by deploying them to appropriate locations. To maximize the potential of IRSs in outdoor multipath environments, we propose an IRS placement method that uses the single reflection point between a BS and user equipment (UE). This method estimates the distribution of single reflection points, which are defined as locations that have direct paths to a BS and UE. The maximum points of the estimated distribution are then selected as candidate positions for the IRSs, and the optimal positions are determined from the candidate points. The proposed method is validated through simulation experiments in an outdoor multipath environment.