Age of Information Optimization Scheme for an Intelligent Reflecting Surface Assisted UAV Communication System
In Internet of Things(IoT)systems,channels are highly time-varying,and direct links have a probability of being blocked.A wireless downlink system for an intelligent reflecting surface(IRS)assisted unmanned aerial vehicle(UAV)serving multiple users on the ground is designed to ensure the timely delivery of status update information.The UAV acts as a mobile base station in the downlink,flying along an optimized trajectory and hovering at a suitable loca-tion close to the user on the ground before transmitting data to users on the ground.A multi-constraint optimization prob-lem is modeled by constructing a joint optimization through time discretization and mathematical modeling.The goal is to minimize the information age of the system through the joint optimization of variables such as the UAV trajectory,flow scheduling,and IRS phase shift design.The process of IRS assisting in improving the wireless environment by transmitting signals through reflection,that is,varying the maximum data rate by changing the channel gain,is investi-gated.IRS phase shift adjustment is used to increase the time-varying channel gain to improve the communication qual-ity.Due to the non-convex formulation contained in the objective function and constraint formulation as well as the cou-pling between multiple optimization variables,optimization algorithms are designed using techniques such as successive convex approximation(SCA)and block coordinate descent(BCD)to simplify the non-convex optimization problem to find the solution of the total optimization problem.Simulation results demonstrate that the algorithm can obtain smooth curves,and the age of information in the system decreases significantly with increasing transmit power and data trans-mission rate thresholds,which imply the feasibility of the proposed algorithm.
age of informationintelligent reflecting surfaceusers schedulingtrajectory optimizationblock coor-dinate descent
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