Low-Complexity Random Rotation-based Schemes for Intelligent Reflecting Surfaces

TL;DR

This paper introduces four low-complexity, energy-efficient schemes for IRS-assisted wireless communication that utilize random phase rotations to enhance performance with limited channel information, achieving significant gains and full diversity.

Contribution

The paper presents a novel analytical framework and four new schemes based on random rotations, reducing complexity and energy consumption in IRS-aided systems.

Findings

All schemes achieve full diversity order.

Significant improvements in outage probability and energy efficiency.

Limited channel knowledge required for effective performance.

Abstract

The employment of intelligent reflecting surfaces (IRSs) is a potential and promising solution to increase the spectral and energy efficiency of wireless communication networks. Despite their many advantages, IRS-aided communications have limitations as they are subject to high propagation losses. To overcome this, the phase rotation (shift) at each element needs to be designed in such a way as to increase the channel gain at the destination. However, this increases the system's complexity as well as its power consumption. In this paper, we present an analytical framework for the performance of random rotation-based IRS-aided communications. Under this framework, we propose four low-complexity and energy efficient schemes, based on a coding or a selection approach. Both of these approaches employ random phase rotations and require limited knowledge of channel state information. Specifically, the coding-based schemes use time-varying random phase rotations to produce an equivalent time-varying channel. On the other hand, the selection-based schemes select a partition of the IRS elements based on the received signal power at the destination. Analytical expressions for the achieved outage probability and energy efficiency of each scheme are derived. It is demonstrated that all schemes can provide significant performance gains as well as full diversity order.