A 3D Stochastic Channel Model for 6G Wireless Double-IRS Cooperatively Assisted MIMO Communications

Abstract

In this paper, we propose a three-dimensional (3D) stochastic channel model for double intelligent reflecting surface (IRS) cooperatively assisted multiple-input multiple-output (MI-MO) communications, where two distributed IRSs are respectively deployed near a mobile transmitter (MT) and a mobile receiver (MR). The double-IRS is distributed on the surface of buildings to assist the transmitter to transmit its own signals to the receiver, and meanwhile improve the propagation by passive beamforming at the IRSs. In this channel model, some of the signals transmitted from the MT impinge on the IRS near to the transmitter or/and the IRS near to the receiver before reaching the MR. Some of the signals emitted from the MT impinge on the cluster before arriving at the MR. Furthermore, we study the double-IRS MIMO channel propagation characteristics, i.e., spatial-temporal (ST) cross-correlation functions (CCFs), for different number and layout of the unit cells in the IRSs, as well as the IRS orientation angles. Simulation results are provided to show the channel characteristics of double- IRSs cooperatively assisted MIMO channel models.