# Hierarchical Resource Management for Mega-LEO Satellite Constellation
## 3 Analysis of Resource Management in the MLSCS
### Influencing Factors Associated with Resource Management in the MLSCS  
This study examines the influencing factors associated with resource management in the MLSCS. By identifying and analyzing key technical, operational, and environmental factors, this research aims to provide insights into optimizing resource allocation and management strategies within the MLSCS. Understanding these factors is crucial for enhancing the efficiency and effectiveness of satellite communication systems. The space segment in the MLSCS consists of hundreds to tens of thousands of LEO satellites operating at altitudes ranging from several hundred to two thousand kilometers. Due to their rapid movement relative to terrestrial users, these satellites create a highly dynamic system characterized by continuous changes in network topology and rapidly shifting coverage areas. Additionally, terminals frequently hand over among different satellites and beams, with service requirements also evolving. This dynamic environment necessitates timely adjustments in resource allocation to effectively adapt to these changes, highlighting the importance of developing responsive resource management strategies. In the MLSCS, resource scheduling presents a multi-dimensional and multi-objective optimization problem. The multi-dimensional resources include time (or slots), space (beams in multi-beam or beam-hopping satellite systems), frequency (spectrum, channel, or band), and energy (power). The optimization objectives include maximizing throughput (or system capacity), minimizing delay or cost, and maximizing user satisfaction. The MLSCS serves global users; however, the system's high dynamic characteristics and imbalanced global spectrum resource utilization lead to fluctuating availability of spectra for LEO satellites and low utilization efficiency. Given the limited satellite resources, it is crucial to identify the main factors affecting spectrum scheduling in space systems, which include the following:  
* Regionality of spectrum usage policy. The available spectrum is different in different countries and regions. Therefore, the available spectrum also changes dynamically with the movement of SBSs. * Interference from open space. The electromagnetic environment in space is complex and rigorous, and there are various types of intentional and unintentional interference to SBSs and user terminals. In particular, the interference of terrestrial base stations introduced by the application of 5G extended frequency bands has an effect on the resource scheduling of the MLSCS. * Protection of GEO satellite spectra by the ITU (International Telecommunication Union). The MLSCS requires multi-satellite collaborative coverage to avoid interference from GEO satellites, especially in mid- and low-latitude areas. * Intra-system interference. For Walker satellite constellations, intra-system interference introduced by the aggregation of satellites in the north/south pole areas needs to be optimized and controlled. * Transmission capacity of SBSs. Generally, the capacity of a single satellite is limited, so for hotspot areas that need enhanced and urgent services, such as earthquake relief, the regional service volume can increase dramatically in a short time, and it is necessary to allocate more resources to meet users' demand in a collaborative way. Hence, multi-satellite emergency resource scheduling is required. * Onboard processing capability. Due to the limited caching and computing capacity of satellites, it is difficult to realize complex resource scheduling algorithms and massive data exchanges, especially for cross-regional resource scheduling planning, which needs careful consideration. In summary, the MLSCS faces challenges due to limited satellite capacity, insufficient spectrum, and inadequate service sensing capabilities. These limitations make it difficult to adapt to the complex and rapidly changing electromagnetic environment and evolving service demands.