# Hierarchical Resource Management for Mega-LEO Satellite Constellation
## 7 Performance Assessments
### Assessment Metrics
#### 7.1.4 User Satisfaction
In the MLSCS, various capacity evaluation indicators are used, including single-channel capacity, single-beam capacity, single-satellite capacity, system (or network) capacity, and congestion probability. Single-channel capacity determines the maximum information rate that an SBS can provide to a single user. Single-beam capacity represents the capacity that a single beam of a satellite can provide to its coverage area, while single-satellite capacity defines the total capacity a single satellite can offer. System capacity, on the other hand, indicates the maximum capacity that the MLSCS can provide to users worldwide. Finally, congestion probability measures the likelihood of link congestion occurring under certain network load conditions, reflecting the system's optimization capabilities in resource scheduling and load balancing. * Multiple access. Multiple access directly reflects the system's ability to provide services to users, which is determined by access resources, the air interface waveform, and the multiple access protocol. The access capacity represents the maximum number of users or transmission rate that can access simultaneously through a single channel, single beam, single satellite, or the entire system. The access delay is the duration from the moment a user sends an access request (in grant-based access) or data (in grant-free access) to the successful access. Grant-based access requires a user to request permission before transmitting, while grant-free access allows users to transmit data without prior permission. The access success probability is a crucial indicator, determined by the number of users attempting to access simultaneously, the multiple access protocol, available access resources, and multi-user detection (MUD) approaches. * Quality of Service. QoS refers to the ability of a network to utilize various technologies to provide improved service to specified users and address issues such as network delay and congestion. QoS assurance is crucial for networks with limited capacity and resources, especially in applications that require a fixed transmission rate and are sensitive to delay, such as streaming multimedia and IoV applications. Therefore, similar to terrestrial networks, common QoS indicators such as the bit error ratio (BER), transmission rate, end-to-end delay, and call drop ratio are also included in the performance evaluation of the MLSCS. * Adaptability. Adaptability reflects how well a system performs and includes terminal availability, reliability, scalability, maintainability, and networking flexibility. Terminal availability is measured based on the usability, learnability, human-machine interaction, response speed, stability, and security of user terminals. Reliability indicates the ability of a system, such as an SBS, to perform a specified mission without failure within a certain period and under certain conditions. In the MLSCS, reliability is measured by the degree of connectivity, redundancy, and connectivity probability. The degree of connectivity and connectivity probability determines the likelihood that service data have an end-to-end path in the system. Redundancy reflects the ability or probability of finding an alternative device or link when the current one fails. Scalability, maintainability, and networking flexibility depict the ability of the MLSCS to expand or add new entities, enrich functions, improve performance, recover from failures, and evenly change the network topology and service flows to form various subnets or specialized networks.