IRS Auxiliary UAV Communications: Channel Modeling and Performance Analysis

In this letter, based on the theory of electromagnetic (EM) wave, an intelligent reflecting surface (IRS) assisted channel model for unmanned aerial vehicle (UAV) communications is proposed. The proposed model reveals the relationship between the received signal power of the IRS and the horizontal rotation angle, the size, and the reflection phases of IRS reflection units. The reflection phases are designed to ensure all signals reflected by IRS are phase aligned, and the theoretical result of the received signal power of IRS assisted link is in direct proportion to the square of the total geometric area of the IRS, which accords with the measurement results obtained in the real outdoor scene. In this letter, the smallest geometric area of the IRS, for which the path loss of the IRS-assisted link is equal to that of the direct link, is investigated. With the increase of the carrier frequency, the smallest geometric area gradually decreases. Finally, we investigate the ergodic sum capacity and obtain the closed-form tight upper bound, which is validated through Monte-Carlo simulation results.