Energy-efficient trajectory optimization in uav-based internet of things (Iot) network with delay tolerance

. With high flexibility and the ability to achieve better wireless channels, the utilization of unmanned aerial vehicles (UAVs) in internet-of-things (IoT) network has gain great popularity. However, the limitation of the power supply and the movement of the UAV make it necessary to optimize the UAV’s trajectory to maximize the ground coverage and prolong the communication duration. In this paper, we consider a scenario where the UAV flies in a circular trajectory in the air and equips the transceiver to collect the data with delay tolerance from a sets of the devices in a certain region. In this way, we formed a UAV-based IoT network. Our aim is to achieve the largest communication coverage by optimizing the altitude and radius of UAV’s trajectory under the given transmitting power, so as to achieve the energy-efficient communication coverage. Besides, the situation that the directional antenna is also deployed on the UAV to improve the energy utilization. Then, we model the optimization problem as a joint 2-dimensional optimization problem and propose an exhaustive search (ES) over a 1-D parameter in a certain range. Numerical results are presented showing the optimal altitude and radius in the different cases and the antenna beam angles.