Digital Twin Satellite Networks Toward 6G: Motivations, Challenges, and Future Perspectives

The advantages of Low Earth Orbit (LEO) satellite networks including high throughput, short latency, and seamless coverage have inspired increasing vendors to construct their own satellite constellations. And the widely recognized 6G technology, Satellite-Air-Ground Integrated Networks (SAGINs), has also driven operators to develop the satellite communications and network services. However, the configuration and management of satellite networks are challenged by the high dynamics, ubiquitous heterogeneity, and significant complexity, while the cost of trial and errors is too high to be tolerant. Moreover, current satellite simulation platforms have the limitations of deficient considerations and unrealistic assumptions, resulting in the low reliability of the evaluated solutions. To address these problems, Digital Twin (DT) has been regarded as a revolution technology to imitate satellite operation and optimize network performance by creating the virtual models of physical satellites and enabling their bidirectional data exchange. In this paper, we introduce the motivations and challenges of Digital Twin Satellite Networks (DTSNs). The procedures to construct the DT model are offered, while a case study is provided to illustrate the performance improvement. Future promising research directions have also been discussed.