# Hierarchical Resource Management for Mega-LEO Satellite Constellation
## 7 Performance Assessments
### Assessment Metrics
#### 7.1.4 User Satisfaction  
Service demand volume: This refers to the total user requests for service within the system or SBS's service area over a specified period (e.g., monthly). It indicates the level of demand placed on the system. Actual service volume (or throughput): This represents the amount of service successfully provided by the system or SBS during the same period. It reflects the system's capacity to meet demand. Degree of satisfaction: This metric indicates how well the system or SBS meets user demand, calculated as the ratio of actual service volume to service demand volume. A high degree of satisfaction (close to 1 or 100%) suggests good performance, while a lower degree might indicate underservicing or inefficiencies. The complexity of satellite communication systems necessitates the development of a multi-level evaluation indicator system that incorporates both qualitative and quantitative indicators. The characteristics of this system are shaped by the interplay of various factors, reflecting the intricate nature of satellite communications. Generally speaking, the degree of system completion depends on the support of different capabilities and must fully reflect the overall needs of the system. To establish an effective evaluation system, it is crucial to adhere to the principles of systematicness, hierarchy, and adaptability. Systematicness ensures that all relevant aspects of the system are considered, hierarchy organizes the evaluation indicators into manageable levels, and adaptability allows the system to evolve with changes in technology and requirements. The hierarchical structure of the evaluation indicators, as shown in Table 2, provides a framework for organizing and evaluating the system. This structure is designed to capture the complexity of satellite communication systems in a structured and systematic manner. A brief elaboration of the hierarchical structure is as follows:  
* Coverage. The coverage indicator is a critical aspect of SBSs, reflecting their coverage characteristics and their influence on system performance. It is primarily described by three key metrics: the single-satellite coverage ratio, the double-satellite coverage ratio,and the multi-satellite coverage ratio. The single-satellite coverage ratio represents the fraction of the Earth's surface covered by only one satellite within the system. Users in this area can only be served by one satellite, resulting in limited robustness and flexibility. If the single satellite or its space-ground link fails, users in this area may experience service disruptions. In contrast, users in the double-satellite coverage area can be served by two SBSs. This dual coverage allows for seamless handover to another satellite when one space-ground link goes wrong, greatly improving robustness and scheduling flexibility. Users in the multi-satellite coverage area enjoy even higher levels of robustness and flexibility, as they can be served by multiple SBSs. However, this increased coverage comes with a trade-off: more complex interference patterns among the satellites, which can challenge system performance. To address these interference issues, practical and effective interference management strategies and methods are crucial. Techniques such as power control, which adjusts the transmit power of satellites to minimize interference, beamforming, which directs signals to specific areas to reduce unwanted interference, and frequency reuse planning, which optimizes the use of frequencies to avoid interference, are all essential tools in ensuring optimal system performance. By implementing these strategies, system designers can harness the benefits of multi-satellite coverage while mitigating the associated interference challenges. * Capacity. Capacity is a critical indicator for measuring the performance of communication systems. A larger capacity allows for a higher information rate to be provided to users, directly enhancing the QoS.