Abstract:

Unmanned Aerial Vehicle （UAV） is flexible and easy to deploy， and can assist Mobile Edge Computing （MEC） to help wireless systems improve coverage and communication quality. However， there are challenges such as computational latency requirements and resource management in the research of UAV-assisted MEC systems. Aiming at the delay problem of UAV providing auxiliary calculation services to multiple ground terminals， a Twin Delayed Deep Deterministic policy gradient （TD3） based Task Offloading Algorithm for Delay Minimization （TD3-TOADM） was proposed. Firstly， the optimization problem was modeled as the problem of minimizing the maximum computational delay under energy constraints. Secondly， TD3-TOADM was used to jointly optimize terminal equipment scheduling， UAV trajectory and task offloading ratio to minimize the maximum computational delay. Simulation analysis results show that compared with the task offloading algorithms based on Actor-Critic （AC）， Deep Q-Network （DQN） and Deep Deterministic Policy Gradient （DDPG）， TD3-TOADM reduces the computational delay by more than 8.2%. It can be seen that TD3-TOADM algorithm has good convergence and robustness， and can obtain the optimal offloading strategy with low delay.

Key words: Mobile Edge Computing (MEC), Unmanned Aerial Vehicle (UAV), task offloading, trajectory, deep reinforcement learning

摘要：

无人机（UAV）灵活机动、易于部署，可以辅助移动边缘计算（MEC）帮助无线系统提高覆盖范围和通信质量，但UAV辅助MEC系统研究中存在计算延迟需求和资源管理等挑战。针对UAV为地面多个终端设备提供辅助计算服务的时延问题，提出一种基于双延迟深度确定性策略梯度（TD3）的时延最小化任务卸载算法（TD3-TOADM）。首先，将优化问题建模为在能量约束下的最小化最大计算时延的问题；其次，通过TD3-TOADM联合优化终端设备调度、UAV轨迹和任务卸载比来最小化最大计算时延。仿真实验分析结果表明，与分别基于演员-评论家（AC）、深度Q网络（DQN）以及深度确定性策略梯度（DDPG）的任务卸载算法相比，TD3-TOADM得到的计算时延减小了8.2%以上。可见TD3-TOADM能获得低时延的最优卸载策略，具有较好的收敛性和鲁棒性。

关键词: 移动边缘计算, 无人机, 任务卸载, 轨迹, 深度强化学习