# Hierarchical Resource Management for Mega-LEO Satellite Constellation
## 1 Introduction  
In recent years, low-cost rocket launches and advanced manufacturing technologies have facilitated the deployment of satellite Internet, particularly through low Earth orbit (LEO) satellites. The low orbital altitude of LEO satellites results in minimal space-ground transmission delays, making them well-suited for delay-sensitive services and application scenarios, such as multimedia entertainment, the Internet of Vehicles (IoV), and real-time control. Additionally, LEO satellites enable terminal miniaturization due to low propagation loss, while dense constellation deployment ensures seamless global coverage. Consequently, the MLSCS has garnered significant attention from governments and global industries, leading to extensive deployments in recent years [1]. The Starlink system, developed by Space Exploration Technologies (SpaceX) and OneWeb, serves as a prominent example of satellite Internet deployment. SpaceX initiallyplanned to deploy two sub-constellations, consisting of 4425 satellites at an orbital altitude of 1150 km and 7518 satellites at an orbital altitude of 340 km, to provide V-band and E-band broadband Internet access services for global users. In November 2018, SpaceX adjusted its orbital altitude from 1150 km to 550 km [2] and the latest plan includes launching 42,000 satellites at multiple different orbital altitudes. By 30 October 2024, the total number of Starlink satellites has reached 7213, of which more than 1400 were launched in 2024. According to the ITU milestone requirements, the SpaceX needs to complete the launch of 1193/5963/11,926 satellites in the Starlink Phase I&II by 2025/2028/2030, and the launch of 3000/15,000/30,000 satellites in the Starlink Phase III by 2028/2031/2033. [PERSON], the CEO of SpaceX, announced on platform X (formerly Twitter) that Starlink has achieved breakeven cash flow on 2 November 2023. The OneWeb constellation offers users impressive connectivity capabilities, providing up to 400 Mbps downlink and 30 Mbps uplink rates. This high-speed Internet access is designed to support a variety of vertical application scenarios, including aviation, maritime operations, and cellular communications. Different types of terminals can be utilized to meet the specific needs of these sectors, enhancing connectivity and enabling innovative solutions across diverse industries [3; 4]. The OneWeb constellation provides users with global seamless coverage and commercial satellite access. As of now, OneWeb has successfully launched 618 of its planned 648 satellites, indicating that the deployment of the first orbital shell of its space network is nearing completion. This achievement is a significant step towards enhancing global connectivity and expanding access to satellite Internet services. Radio resource management is a key technology in wireless communication systems, significantly impacting the performance of the MLSCS. As the number of system users and services increases, along with the expansion of application scenarios, it becomes essential to optimize radio resource scheduling to enhance satellite efficiency and steadily improve network capacity. Therefore, the architectural design of radio resource management systems in the MLSCS requires functional decoupling and scalability to meet these evolving demands. Unlike traditional geosynchronous Earth orbit (GEO) satellite communication systems, the coverage area of satellites in the MLSCS changes dynamically. In comparison to constellation satellite communication systems with fixed beams, such as Iridium and OneWeb, some LEO satellite constellation systems exhibit insufficient service beam coverage. This limitation increases the need for on-demand service beam scheduling, known as beam-hopping. Compared to traditional satellite communication systems, the application of beam-hopping can address the imbalanced characteristics of service distribution.