Power Optimization for Intelligent Reconfigurable Surfaces in Indoor Environment Using Discrete Phase and Amplitude Shifts

Abstract

Reconfigurable Intelligent Surfaces (RISs) have the ability to make the concept of smart radio environments a reality, by utilizing the special characteristics of meta-surfaces. In this paper, we discuss how an IRS-assisted enhance link quality and coverage between an access point (AP) located on a wall and an antenna user in an indoor environment. specifically, we formulate and solve a non-convex constraint issue to minimize transmit power at the antenna of the transmitter and maximize the received power at user-end by optimizing both phase/amplitude shifts, as well as maximizing Energy Efficiency (EE) by proposing an Optimizing Alternating (OA) technique to solve that issue. The result of simulation show that IRS helps the indoor environment to gain a strong signal and make a virtual link between the AP and USER. Moreover, it is verified that the IRS by joint amplitude/phase shifts and OA are able to make a significant improvement of about 10 dBm by maximizing both discrete phase/amplitude shifts. Also, the IRS be able to create “signal hot-spots” in some points between the IRS and USER to deliver a strong signal and produce 30% improvement as well as maximizing the energy efficiency and keep it highest until 30 dB of (signal to noise ratio) SNR. In this paper, we assume that the user is in a bad situation and not be able to receive a good signal from the base station in which by helping RIS the user receives a higher SNR. Finally, we compare our work with a reference system that only uses non-direct NLOS transmission.