The development of an integrated space-air-ground network (SAGIN) requires sophisticated satellite Internet emulation tools that can handle complex, dynamic topologies and offer in-depth analysis. Existing emulation platforms struggle with challenges like the need for detailed implementation across all network layers, real-time response, and scalability. This paper proposes a digital twin system based on microservices for satellite Internet emulation, namely Plotinus, which aims to solve these problems. Plotinus features a modular design, allowing for easy replacement of the physical layer to emulate different aerial vehicles and analyze channel interference. It also enables replacing path computation methods to simplify testing and deploying algorithms. In particular, Plotinus allows for real-time emulation with live network traffic, enhancing practical network models. The evaluation result shows Plotinus's effective emulation of dynamic satellite networks with real-world devices. Its adaptability for various communication models and algorithm testing highlights Plotinus's role as a vital tool for developing and analyzing SAGIN systems, offering a cross-layer, real-time and scalable digital twin system.

翻译：构建空天地一体化网络（SAGIN）需要能够处理复杂动态拓扑并提供深度分析的卫星互联网仿真工具。现有仿真平台在应对全网络层精细化实现、实时响应及可扩展性等挑战时仍存在不足。本文提出一种基于微服务的卫星互联网数字孪生系统——普洛提努斯，旨在解决上述问题。该系统采用模块化设计，支持灵活替换物理层以仿真不同飞行器并分析信道干扰，同时允许更换路径计算方法以简化算法测试与部署。特别地，普洛提努斯可实现实时网络流量闭环仿真，增强实测网络模型的实用性。评估结果表明，该系统能够有效模拟真实设备环境下的动态卫星网络，其多样化的通信模型适配能力与算法测试功能，彰显了普洛提努斯作为跨层次、实时化、可扩展数字孪生平台在SAGIN系统开发与分析中的核心价值。