Analysis and Optimization of Outage Probability in Multi-Intelligent Reflecting Surface-Assisted Systems

TL;DR

This paper investigates the outage probability in multi-IRS-assisted wireless systems with Rician fading, analyzing and optimizing performance under various conditions, and providing asymptotic results in high SNR regimes.

Contribution

It is the first study to analyze and optimize outage probability in multi-IRS-assisted systems, considering phase shifts based on LoS components and deriving asymptotic behavior.

Findings

Optimal outage probability decreases with more IRSs and elements when LoS is strong.

Outage probability reduces as LoS power increases.

Asymptotic outage probability diminishes at high SNR regimes.

Abstract

Intelligent reflecting surface (IRS) is envisioned to be a promising solution for designing spectral and energy efficient wireless systems. In this letter, we study a multi-IRS-assisted system under Rician fading where the phase shifts adapt to only the line of sight (LoS) components. First, we analyze and optimize the outage probability of the multi-IRS-assisted system in the slow fading scenario for the non-LoS (NLoS) components. We also show that the optimal outage probability decreases with the numbers of IRSs and elements of each IRS when the LoS components are stronger than the NLoS ones. Then, we characterize the asymptotically optimal outage probability in the high signal-to-noise ratio (SNR) regime, and show that it decreases with the powers of the LoS components. To the best of our knowledge, this is the first work that studies the outage probability in multi-IRS-assisted systems.