Joint Access Slot Scheduling and Backhaul Bandwidth Allocation for Space-Air-Ground Integrated Networks

Space-air-ground integrated networks (SAGINs) can provide communication services for hard-to-reach areas. Low earth orbit (LEO) satellites and high altitude platforms (HAPs) are key components of SAGIN, with LEO satellites providing global coverage and HAPs providing closer and more stable mass access to users on the ground. In this paper, we study a HAP assisted communication scheme in SAGIN, focusing on serving as many users as possible while meeting their QoS requirements. Data flows between LEO satellite and users can be directly transmitted to the user through LEO satellite or relayed to the user by HAP. We propose a joint access slot scheduling and backhaul bandwidth allocation algorithm. For access links, according to QoS requirements and rates, users with fewer transmission slots are preferentially scheduled to maximize the utilization of time slot resources. The bandwidth allocation of backhaul links is based on the user association results of access links, and the user with lower bandwidth is preferentially scheduled. Extensive simulation results demonstrate that the proposed algorithm can effectively improve the system throughput and meet the QoS requirements of as many users as possible.