Research On Trajectory And Transmission Strategy Of Cellular-Connected Unmanned Aerial Vehicles With Connectivity Constraint

Among the many applications of Unmanned Aerial Vehicle(UAV),Cellular-connected UAV has become a popular application direction along with the development of 5G mobile communication.For example,the ground base station directs the drone to conduct safety inspections,fire rescue and other activities.However,limited endurance has always been a common shortcoming of drones.In many specific application scenarios(such as aerial photography,information collection,etc.),drones must return home regularly to charge them.Therefore,when deploying UAVs to perform tasks,it is particularly important to carry out reasonable path planning and reduce unnecessary flight energy consumption.This thesis uses the cellular network drone to collect ground node information as a scenario,and respectively studies how to complete the information collection task in the shortest time and how to minimize the energy consumption of ground nodes.The specific research content of this article can be summarized as follows:1.The communication design of the celluar-connected UAV from the perspective of task completion time.Consider a networked UAV data collection system.The UAV must be connected to the cellular network,and the time for the UAV to complete the information collection task is shortened as much as possible through the optimization of the trajectory.This article first uses the spiral algorithm to cluster the ground nodes according to the relative distance,and finds the center point of the cluster(stationary point,cluster head,UAV staying point).Then use the point-to-point distance algorithm based on geometric theory to obtain the distance between each stagnation point,and through the ant colony algorithm,obtain the visit order of the UAV to all stagnation points,and finally obtain the UAV’s trajectory corresponding to the minimum task completion time.Further considering that the UAV can be disconnected from the ground base station for a short time,this paper studies the trajectory optimization problem under the limited interruption time.Compared with the traditional full connection scheme,it can further shorten the completion time and serve more ground terminal.Finally,the simulation results given prove the effectiveness of the algorithm proposed in this paper.2.Cellular-connected UAV communication design from the perspective of ground node energy.Consider using Cellular-connected UAVs for data collection.On the premise of completing data transmission tasks on the ground,in order to prolong its survival time,it is necessary to reduce the energy used for information transmission on the ground as much as possible.For this reason,this paper studies the trajectory of the UAV to maximize the remaining energy of the ground node when the UAV mission is completed in a certain time.First,the improved spiral algorithm is used to find the stagnation point where the energy consumption of the node is minimized,and then the point-to-point distance algorithm and the ant colony algorithm are used to obtain the trajectory of the UAV.Further considering the limited mission time of a single UAV,this paper proposes the use of dichotomy to optimize the trajectories of two UAVs,further reducing the task completion time and increasing the remaining energy of the node.