Performance Analysis of Intelligent Reflecting Surface Assisted Wireless Communication System

In this paper, we investigate the end-to-end performance of intelligent reflecting surface (IRS)-assisted wireless communication systems. We consider a system in which an IRS is deployed on a uniform planar array (UPA) configuration, including a large number of reflecting elements, where the transmitters and receivers are only equipped with a single antenna. Our objective is to analytically obtain the achievable ergodic rate, outage probability, and bit error rate (BER) of the system. Furthermore, to maximize the system's signal-to-noise ratio (SNR), we design the phase shift of each reflecting element and derive the optimal reflection phase of the IRS based on the channel state information (CSI). We also derive the exact expression of the SNR probability density function (p.d.f.) and show that it follows a non-central Chi-square distribution. Using the p.d.f., we then derive the theoretical results of the achievable rate, outage probability, and BER. The accuracy of the obtained theoretical results is also verified through numerical simulation. It was shown that the achievable rate, outage probability, and BER could be improved by increasing the number of reflecting elements and choosing an appropriate SNR regime. Furthermore, we also find that the IRS-assisted communication system achieves better performance than the existing end-to-end wireless communication.