Abstract: Age of Information (AoI) describes the time from the time when information is sent to the time when it is received, which can accurately measure the value of data. In order to minimize the average AoI in emergency communication, unmanned aerial vehicles (UAVs) are introduced as information relay and a task assignment and trajectory optimization algorithm based on deep reinforcement learning framework is proposed. Firstly, the relationship between the original AoI minimization problem and UAV-assisted emergency communication is analyzed and proved, and the AoI minimization problem is divided into two stages to solve. Secondly, in order to reduce the ineffective flight time of drones, new planning strategies have been developed to make the trajectory smoother by incorporating disaster nodes along the way into the trajectory. Finally, in order to avoid the UAV repeatedly visiting the same rescue group, a centralized information sharing mechanism is designed to save energy consumption and information distribution time. Experimental results show that compared with traditional optimization algorithms, the proposed optimization algorithm can achieve a smaller information age.

Key words: UAV-assisted Internet of Things, Age of Information, task assignment, trajectory optimization, Deep reinforcement learning