Achievable Rate Analysis of UAV-Mounted RIS-Assisted Link with UAV 3D Location Variation

Reconfigurable intelligent surface (RIS) can enhance the communication performance by contributing a virtual line-of-sight (VLoS) link between the transceivers when the LoS path is blocked. However, conventional terrestrial deployed RISs are limited to half-space reflection with restricted locations. In this paper, we consider the deployment of RIS on an unmanned aerial vehicle (UAV), which is also referred to as UAV-mounted RIS, to explore its advantages in full-space reflection and flexible mobility. We first develop a novel channel model for the proposed UAV-mounted RIS-assisted multiple input multiple output (MIMO) communications in the presence of three-dimensional (3D) location variation of the UAV-mounted RIS. Based on the proposed model, the link achievable rate is derived as a metric to investigate the impact brought by the location variation. Numerical results are provided to verify the accuracy of our derived results.