Uplink performance Analysis of RIS-Assisted UAV Communication Systems With Random 3-D Mobile Pattern

Reconfigurable intelligent surface (RIS) is playing a growing and ever-more significant role in constructing six-generation (6G) wireless networks due to its properties of low-cost and easy-integration. Current studies about RIS-assisted communication generally assume the RISs are deployed at fixed position or devices, however with the rapid development of unmanned aerial vehicle (UAV) technology, this readily flying wireless access platform is increasingly used to realize reliable communication. If the RISs are mounted on random 3-D (three-dimension) mobile UAVs, how to investigate the uplink transmission of RIS-assisted UAV communication systems would be a great challenge. To resolve this open issue, we establish a novel theoretical model to analyze the uplink performance of RIS-assisted UAV communication systems with random 3-D mobile pattern. In the modeling process, we firstly provide a random 3-D mobile model for UAVs, where the random waypoint and uniform mobility models are simultaneously used. Next we build an end-to-end (E2E) transmission model for RIS-assisted UAV communication system, where the impacts of channel fading type, RIS configuration, UAV's mobility and association policies are comprehensively considered. Combining the above two models, we derive the analytical expressions of uplink transmission metrics, and make a bound performance analysis on this base. Finally, we evaluate the uplink performance of RIS-assisted UAV communication system with random 3-D mobile pattern, and verify the proposed theoretical model.