## 4 Capability Evaluation of a Satellite Communication System
### Capability Indicator System Construction  
In order to establish a comprehensive evaluation model for the capability demand satisfaction of SCS, it is necessary to decompose the demands into specific capabilities that can be assessed. In this regard, a set of capability indicators must be established to assess the level of performance for each capability. These indicators should be measurable, reflect the key attributes of each capability, and be structured in a hierarchical system. Therefore, a thorough analysis of the demands and capabilities is required to establish an evaluation model that can effectively guide the development of the SCS. The process of constructing the indicator system is illustrated in Figure 1.  
* Step 1: Task analysis. The initial step involves the decomposition of mission tasks to identify the capabilities that are necessary to support these tasks. Given that mission tasks are diverse in nature, the capabilities required to accomplish them are also varied. Thus, by breaking down the core mission task \(T\), we obtain independent and unique sub-tasks at different levels, denoted as \[T=\{T_{1},T_{2},\cdots,T_{i}\}.\] (45) Secondly, refine tasks into activity options. The unit-level activities \(A\) describe the specific behavior required to complete the tasks, and their corresponding relationships with capabilities are relatively stable, allowing for mapping with capability indicators. We gradually decompose the tasks until we reach activities that correspond to capability indicators \[T_{i}=\{A_{i}^{1},A_{i}^{2},\cdots,A_{i}^{j}\}.\] (46) It is worth noting that lower-level tasks can simultaneously support multiple upper-level tasks. To enhance the accuracy of our task description, we aggregate the final level of sub-tasks and activities, eliminating any duplication or redundancy.
* Step 2: Capability analysis. The specific execution of an activity requires certain capabilities, creating a one-to-one or one-to-many mapping relationship between activities and capabilities, denoted as follows: \[A_{i}^{j}=\{Ca_{1},Ca_{2},\cdots,Ca_{m}\}.\] (47) Capabilities are further broken down into multiple sub-capabilities until they arrive at measurable capability indicators. \[Ca_{m}=\{ca_{m}^{1},ca_{m}^{2},\cdots,ca_{m}^{n}\},\] (48) representing \(n\) sub-capabilities under capability \(Ca_{m}\).
* Step 3: Indicator analysis. A capability is defined by one or more capability indicators \(ca_{m}^{n}=\{I_{1},I_{2},\cdots\}\), which are measurable capability attributes. We decompose the capabilities to obtain sub-capabilities, and this iterative decomposition process continues until we reach a set of basic measurable, operable, and understandable attributes, that is, technical and tactical indicators of the system.  
The SCS primarily performs information transmission tasks. The degree of task completion varies depending on its information transmission capability, information security and protection capability, and other factors. Through the process outlined above, we have constructed a general evaluation indicator system for the SCS, consisting of three main capability indicators: service acquisition capability, information transmission capability, and security capability. Moreover, each of the main indicators was decomposed into multiple quantifiable individual indicators. As a result, we have obtained a hierarchical capability indicator system for the SCS, as shown in Figure 2.