# SatScope: A Data-Driven Simulator for Low-Earth-Orbit Satellite Internet
## 3 SatScope Model Framework  
SatScope is a network simulator designed specifically for LEO satellite internet systems. It comprises four main components: space segment modeling, ground segment modeling, network simulation, and simulator interfaces. The overall architecture of the model is illustrated in Figure 2.  
Figure 2: Model framework diagram. SatScope consists of four parts: space segment modeling, ground segment modeling, network simulator, and simulator interface. Researchers input TLE and Traceroute data into SatScope, which are processed separately by the space segment and ground segment modeling, and the results are fed into the network simulator to simulate the LEO satellite internet. Researchers can also use the simulator interface to verify the algorithm performance of the satellite network communication system.  
**Space Segment Modeling.** Leveraging large constellation performance simulation techniques, SatScope captures the inherent dynamism of LEO satellite internet systems, enabling orbital-level granularity simulations. By importing recent TLE data from CelesTrak ([[https://celestrak.org/NORAD/](https://celestrak.org/NORAD/)]([https://celestrak.org/NORAD/](https://celestrak.org/NORAD/)), accessed on 20 May 2025. updated daily), SatScope divides satellites into shell and orbital plane segments, constructing a lightweight real-time model for Starlink satellites and providing dynamic visualization for individual shells.  
**Ground Segment Modeling.** Utilizing large-scale asynchronous network measurement technology, SatScope facilitates extensive measurements of ground segment equipment, thereby achieving accurate modeling and simulation. Building on our team's previous work [42] (the open-source tool FlashRoute [43] also supports large-scale asynchronous network topology measurements), we conducted cost-effective, large-scale asynchronous path measurements of the Starlink ground segment from a standard internet server node. Based on the characteristics of the CGNET protocol, SatScope implements a method to identify ground devices, thus constructing a data-driven model of terminal user-and-ground station distribution.  
**Network Simulator.** Building upon both space and ground segment models, SatScope simulates star-to-ground network connections and large-scale node dynamics. According to predefined access rules, SatScope enables ground nodes to select the largest-weight visible satellite for connection to the space segment. Within SatScope, researchers can configure satellite network topologies, routing algorithms, load-balancing schemes, and traffic generators to dynamically simulate LEO satellite internet operations.  
**Simulator Interface.** SatScope offers researchers a comprehensive suite of APIs, including Space API, Ground API, and Environment API. The Space API allows for the acquisition and tracking of satellite states, while the Ground API supports the addition and optimization of ground nodes. The Environment API is used to test and optimize network topologies and routing algorithms. Through these interfaces, researchers can analyze and optimize satellite constellation configurations, enhance mission efficiency, and ensure network stability and efficiency across various environments.