Joint Optimization of Trajectory Control, Task Offloading, and Resource Allocation in Air-Ground Integrated Networks

In an air-ground integrated network (AGIN), low-altitude unmanned aerial vehicles (UAVs) and a high-altitude platform (HAP) operate synergistically to support computationally expensive and delay-critical applications of mobile ground devices (GDs). UAVs obtain tasks from GDs, execute the tasks, and offload some of the tasks to the HAP. In AGINs, the trajectory control of a UAV swarm should provide optimal coverage to randomly distributed mobile GDs. The limited resources of UAVs, such as energy, computation, caching, and bandwidth, result in further challenges. Therefore, a joint optimization problem is formulated in this study to minimize the task execution delay and energy consumption of UAVs by optimizing the UAV’s trajectory, GD association, task-offloading ratio, and resource allocation. The limited resources, maximum task execution delay, task queue size, and mobility of UAVs are regarded as key constraints. Solving the problem is intricate owing to the complex mixed-integer nonlinear constraints coupled with a large continuous and discrete decision space. To track the dynamics in AGINs and efficiently solve the problem above, we utilize a swarming behavior-integrated multiagent gated recurrent unit-based actor and multihead attention-based critic network (SMA-GAC) framework. Results of simulative evaluation show that the proposed SMA-GAC outperforms baseline methods.

I. Introduction

Owing to the rapid growth of delay-sensitive and computationally intensive Internet of Things (IoT) applications, future wireless networks will be inundated with challenges to satisfy the Quality-of-Service (QoS) requirements for mobile ground devices (GDs). However, GDs have limited battery and computational resources. Thus, to alleviate the excessive burden on resource-constrained GDs, mobile edge computing (MEC) services have been proposed [1], [2]. The GDs can offload intensive tasks to the MEC server. However, in post-disaster hotspots and remote areas, deploying terrestrial MEC servers is challenging [3], [4].