Power Focusing with Intelligent Reflective Surfaces for Wireless Indoor Communication Systems

Abstract: Intelligent reflective surfaces (IRS) are envisioned to have a significant number of applications in future wireless network systems by reconfiguring the signal propagation to improve system performance. In particular, the IRS's cell elements can independently reflect the incident signal by tuning its phase and achieving passive beamforming to enhance the received signal of the user equipment. We study the IRS-aided point to point multiple-input single-output (MISO) wireless system where one IRS is deployed to assist the wireless communication network from a multi-antenna base station to a single-antenna user. The user receives the signal transmitted directly from the base station as well as that reflected by the IRS. We aim to maximize the total received signal power at the user by jointly optimizing the (active) transmit beamforming at the base station and (passive) reflect beamforming by the IRS's reflective cells. First, we propose a signal model for the passive IRS-aided wireless network for empty-room and dead-zone scenarios. Second, we propose a beamforming optimization algorithm to analyze the received signal power's maximization for the given scenarios. The performance of the proposed methods is analyzed in an ideal indoor environment where all the antennas both in the base station and the IRS are in a perfect line-of-sight propagation environment. Furthermore, numerical results show significant performance enhancement with the use of IRS in typical wireless networks compared to benchmark schemes. The numerical results show how the IRS-aided wireless system compensates for the attenuation loss blocking by the obstacle wall with different materials in the dead-zone scenarios. Moreover, we present the relationship between the size of the IRS and the received signal power and the size of the IRS and the IRS deploying positions, respectively. It is verified that the IRS can drastically enhance the link quality and coverage over the traditional setup without the IRS.