Age of Information Based URLLC Transmission for UAVs on Pylon Turn.

Unlike center users, edge users are unable to achieve reliable data transmission due to severe path loss, and the resulting frequent retransmissions not only bring additional energy consumption but also lead to unacceptable latency. To achieve the performance requirements of ultra-reliable low latency communication (URLLC), we propose an unmanned aerial vehicle (UAV)-aided URLLC scheme for the edge users, in which the age of information (AoI) is utilized as the indicator of system latency. Inspired by the pylon turn of gunboat aircraft, the same flight pattern is used at the fixed-wing UAV in the proposed scenario. To reduce the AoI of edge users, we optimize the hovering radius of the UAV while considering its aerodynamic model. In addition, to reduce the complexity of solving, we simplify the original AoI minimization problem and derive its closed-form result as a suboptimal solution. Simulation results show that our proposed UAV-aided URLLC scheme is beneficial as its average AoI is lower than those of the fixed radius schemes, and the near-optimal AoI performance is achieved by the proposed low complexity method.