## 1 Introduction  
Recently, with the progress of Internet of things technology, smart home, intelligent driving, unmanned monitoring and other terminal and network fusion technology is changing our lives. It is hoped that the functions that can be implemented by terminals will become more and more complex, which means that limited capacity and capability terminals will be unable to solve computation-intensive and latency-critical tasks. Mobile edge computing (MEC) network is a new type of network architecture technology [1]. The MEC server with powerful computing storage capabilities is close to the edge of the network and can effectively reduce the energy consumption and delay caused by the data transmission distance and bandwidth limitations [2, 3]. In environments far from cities (such as emergency rescue, crop condition monitoring, and power line inspection) [4], practical problems occur, including rapid networking, low-cost network coverage, and short-term business requirements. In emergency rescue, when the unfavorable environment causes the ground communication network to be unavailable or unreliable, rapid networking is needed to ensure timely communication of detection and rescue information collected by terminal equipment [5]. The amount of data from monitoring points in agricultural areas is large, and the monitoring points are far away from wireless access points and edge cloud facilities. Monitoring points need to analyze and process crop information for a period of time to get the next stage of cultivation direction. The monitoring points have limited storage and computing capacity and need to establish temporary communication with the edge cloud [6]. The inspection environment of electric power lines is similar to that of agriculture. The location of power lines is remote, and the inspection lines are not fixed, so flexible communication networks are also needed. Evidently, the construction of a fixed MEC service site requires a certain construction period, and the investment cost is extremely low. As a new type of increasingly mature equipment, an unmanned aerial vehicle (UAV) is characterized by its deployment and flexibility [7; 8]. Combined with the MEC network and the UAV which performs MEC server functions in complex environments, the MEC can realize the rapid deployment and flexible offloading of computing tasks [9; 10; 11], with a broad application prospect. The UAV mainly performs two functions in the process of MEC network fusion. One function is to monitor and measure as a terminal device. When the UAV's own data processing ability is weak, offloading its own task to the surrounding MEC server is necessary for calculation [12; 13]. Another function of the UAV is to act as a MEC server by using computing resources on the UAV to process computing tasks sent from the terminal equipment in a timely manner. Route planning is required when the UAV is serving in a highly mobile region. The UAV is a dynamic MEC node, whereas the access point (AP) is a static counterpart, and both provide joint computing services. [PERSON] et al. [14] proposed a second-order random hierarchical game ground MEC (G-MEC) operation mode to coordinate the resources between the UAV and AP and serve users effectively. [PERSON], [PERSON] et al. [15] involved a UAV-assisted edge computing system in which the UAV serves as the ground terminal. The UAV trajectory, offloading task ratio, and user scheduling variables are jointly optimized with the maximum delay and minimum as objectives. The UAV in [16] is used to assist nodes for computing-intensive task execution by providing air and ground offloading and realizing resource scheduling between the terminal and the MEC server. The model has the characteristics of energy perception and delay perception.