A three-dimensional wideband mmWave multiple-input multiple-output channel model for aerial reconfigurable intelligent surface-assisted communication systems

This paper presents a wideband millimeter wave (mmWave) channel model for aerial reconfigurable intelligent surface (ARIS) communications, in which the reconfigurable intelligent surface (RIS) is attached to an unmanned aerial vehicle (UAV) to enable intelligent signal reflections in the air. The model is established according to standard 3GPP channel models and considers important propagation factors, for example, large-scale fading, small-scale fading, and radiation pattern of reflection units (RUs). In addition, the model assumes three-dimensional (3D) rotations of RIS and can capture its effects on channel characteristics. Based on the model, we propose a design method for RIS reflection phases. Statistics including channel amplitude, spatial, temporal, and frequency correlation functions (CFs), and space-Doppler power spectral density (SD-PSD) are obtained. The impacts of RU number, UAV height and speed, and RIS rotation on channel statistics are investigated. Results suggest that the designed reflection phases can effectively mitigate multipath fading and Doppler effect. Compared to the yaw angle of the UAV platform, channel characteristics are more sensitive to the roll and pitch angles. This study presents a mmWave channel model for aerial reconfigurable intelligent surface (ARIS) communications, in which the RIS is attached to an unmanned aerial vehicle to enable intelligent signal reflections in the air. Statistics including channel amplitude, spatial-temporal-frequency correlation function, and space-Doppler power spectral density are obtained. The impacts of reflecting unit number, UAV altitude and speed, and RIS rotations on channel statistics are clarified.image