Joint Association and Power Allocation for Data Collection in HAP-LEO-Assisted IoT Networks

Low earth orbit (LEO) satellites and high altitude platforms (HAPs) have recently gained popularity due to its seamless connectivity and global coverage. The aerial network comprising high altitude platforms (HAPs) collects the generated data of the ground internet of things (IoT) devices and then transmits the aggregated data to the terrestrial data processing center via the LEO satellites. However, LEO satellites are generally orbiting with high speed and their visibility times are limited according to the elevation angle and orbital height. Moreover, it is challenging for the HAPs to determine the feasible LEO satellite to associate with and decide the optimal transmit power due to their power constraint. Therefore, in this paper, we formulate a joint association and power allocation problem to maximize the data transmitted by the HAPs and minimize the energy consumption by considering the HAP's power budget and QoS requirements as well as the data storage and visibility time of the LEO satellites. To address the formulated mixed-integer non-convex problem, the two sub-problems are introduced, namely, HAP-LEO satellite association and power allocation problems, which are then alternately solved by using the GUROBI optimizer and whale optimization method, respectively. The evaluation results have demonstrated that the proposed approach achieves the superior performance when compared to the random scheme.