# Digital Twin Technology-Based Networking Solution in Low Earth Orbit Satellite Constellations
## 1 Introduction  
The deployment of large-scale low Earth orbit (LEO) satellite networks offers a promising solution to achieve truly global access services [1]. Compared to traditional ground infrastructure and geostationary satellites, LEO satellite networks utilize satellites deployed in a low Earth orbit, providing global communication coverage with lower latency and higher throughput. In this context, LEO satellite networks are widely recognized as a core component of future 6G networks. Several companies (e.g., SpaceX, OneWeb, O3B, and Iridium Next) have begun deploying large-scale LEO satellite constellations to gain an advantage in the fierce 'NewSpace' race [2; 3]. Although significant progress has been made in the research of LEO satellite networks, the high trial-and-error costs and limited perception capabilities remain two major issues constraining the further development of the LEO satellite industry. To address these two issues, digital twin technology [4; 5] serves as a reliable paradigm to facilitate the development of LEO satellite networks. By conducting high-precision, multidimensional, and comprehensive dynamic simulations on computers, digital twin technology can create models of physical entities in the virtual world according to certain rules. It establishes connections between the physical and virtual worlds, enabling real-time interactive communication, virtual-to-physical control, self-iterative optimization, and updates. Currently, digital twin technology has become a major focus in both academia and industry. Companies like Siemens and NASA have utilized digital twin technology to construct end-to-end digital twin production system models and virtual systems equivalent to aerospace systems. Several universities, including Wuhan University and the University of Michigan in the United States, have conducted research on the theory and future development of digital twin technology. As such, digital twin (DT)-enabled LEO satellitenetworks provide an efficient tool that can comprehensively evaluate effective and stable collaboration among LEO satellites. On the downside, considering the high-speed orbital motion of satellite constellations and the diverse validation requirements, digital twin (DT)-enabled LEO satellite networks face the following challenges: (i) as space devices moving around the Earth at a speed of 27,000 km/h, satellites cannot provide long-term stable services to users, making existing ground-based network-based digital twin solutions unsuitable for satellite networks; (ii) satellite constellations have different requirements during different stages of construction, making it difficult to meet the twin validation needs of different stages based on a stable solution. Motivated by the above-mentioned challenges, in this study, we strive to develop a DT-enabled LEO satellite networking framework. In particular, we propose a digital mapping method to represent network elements, network connections, and network behaviors. In doing so, we construct virtual models of the physical entities in LEO constellation networks. Following this, based on pre-generated ephemeris and orbital information, we design a network topology simulation method to analyze the satellite topology structure. Lastly, we propose to implement interaction mapping between the physical space and virtual space, thereby meeting the twin validation needs in various stages (before, during, and after) of the construction of the LEO constellation system. Digital twins have found widespread application in satellite platform twinning, yet their usage in low-orbit constellation network protocol twins remains largely unexplored. Due to the limited availability of research references in this area, existing twinning techniques can only be applied by adopting other conceptual frameworks. In this context, the main contributions of this paper are summarized as follows. 1.