Research On Trajectory Optimization And Resource Allocation In UAV Secure Communication

Unmanned aerial vehicles(UAVs)are widely used in wireless communication to enhance the communication dimension and quality of service of the ground communication system due to their deployment flexibility and mobility.On the one hand,because UAV is easy to establish a Line of Sight(Lo S)link,it can carry out fast information transmission with user nodes.On the other hand,because of the broadcast nature of the wireless channel,Lo S also increases the risk of being eavesdropped.As a supplement to the upper encryption technology,the physical layer security can make use of some characteristics of the wireless channel itself to make the system achieve ideal security without the need for a security key.This paper studies the resource optimization scheme of UAV security communication in two different scenarios,and its main work is as follows:(1)UAV utilize their excellent maneuverability to emit artificial noise to assist ground base stations in secure transmission with multiple users.In view of the incomplete uncertainty of the location information of multiple eavesdroppers and the problem of nofly zone during UAV flight,the bounded error model and cylindrical geometric modeling are used to describe them respectively.A joint optimization algorithm was proposed to optimize the trajectory of unmanned aerial vehicles,interference power,and ground base station transmission power,maximizing the minimum average safety capacity of the system in the worst-case scenario.Through comparative simulation,it was verified that the proposed optimization scheme not only ensures system security but also enhances system robustness.The UAV also avoids the no-fly zone with the most effective flight path,saving more time for jamming eavesdroppers.(2)In urban scenarios,UAV serve as aerial base stations,multiplexing the spectrum of primary users to securely communicate with a secondary user on the ground.In response to the problem of obstruction of the Lo S link of drones and excessive interference from secondary users to primary users in crowded building scenarios,Intelligent Reflecting Surface(IRS)is introduced to assist drones in secure communication.By utilizing the feature of IRS,channel parameters can be reconfigured to control the direction of UAV communication links,thereby enhancing the channel quality of the main link and weakening the channel quality of eavesdropping and interference links.A joint optimization algorithm for optimizing UAV trajectory,transmission power,and IRS phase shift matrix has been proposed to maximize the safety capacity of secondary users.Through comparative simulation,it was verified that the optimization scheme not only ensures the security of information transmission,but also significantly improves the channel quality of the transmission link,and significantly suppresses the interference suffered by primary users.