Channel Characterization of IRS-assisted Resonant Beam Communication Systems

TL;DR

This paper introduces an IRS-assisted resonant beam communication system that enhances optical wireless communication by compensating for obstructions and misalignments, using a novel channel model and dynamic power control.

Contribution

It proposes a new IRS-assisted RBC system with frequency doubling, develops a Fresnel diffraction-based channel model, and demonstrates dynamic power control to optimize communication performance.

Findings

IRS-assisted channel compensates for obstructions

Dynamic beam-splitting ratio improves power efficiency

Numerical results confirm enhanced communication robustness

Abstract

To meet the growing demand for data traffic, spectrum-rich optical wireless communication (OWC) has emerged as a key technological driver for the development of 6G. The resonant beam communication (RBC) system, which employs spatially separated laser cavities as the transmitter and receiver, is a high-speed OWC technology capable of self-alignment without tracking. However, its transmission through the air is susceptible to losses caused by obstructions. In this paper, we propose an intelligent reflecting surface (IRS) assisted RBC system with the optical frequency doubling method, where the resonant beam in frequency-fundamental and frequency-doubled is transmitted through both direct line-of-sight (LoS) and IRS-assisted channels to maintain steady-state oscillation and enable communication without echo-interference, respectively. Then, we establish the channel model based on Fresnel diffraction theory under the near-field optical propagation to analyze the transmission loss and frequency-doubled power analytically. Furthermore, communication power can be maximized by dynamically controlling the beam-splitting ratio between the two channels according to the loss levels encountered over air. Numerical results validate that the IRS-assisted channel can compensate for the losses in the obstructed LoS channel and misaligned receivers, ensuring that communication performance reaches an optimal value with dynamic ratio adjustments.