Recently, low-orbit satellite networks have gained lots of attention from the society due to their wide coverage, low transmission latency, and storage and computing capacity. Providing seamless connectivity to users in different areas is envisioned as a promising solution, especially in remote areas and for marine communication. However, when jointly used with terrestrial networks composing satellite-terrestrial networks, the satellite moving speed is much faster than the ground terminal, which can cause inconsistent service from a single satellite, and therefore lead to frequent satellite handover. Moreover, due to the dynamic and time slot visibility of satellites, the topology of an intersatellite changes frequently, which results in loops during satellite handover, thereby reducing the utilization of links. To address these problems, we propose a digital twin-assisted storage strategy for satellite-terrestrial networks (INTERLINK), which leverages the digital twins (DTs) to map the satellite networks to virtual space for better communication. Specifically, we first propose a satellite storage-oriented handover scheme to minimize the handover frequency by considering the limited access time and capacity constraints of satellites. Then, a multiobjective optimization problem is formulated to obtain the optimal satellite by genetic algorithm. Finally, considering the timing visibility of the satellite links, a digital twin-assisted intersatellite routing scheme is introduced to improve the quality of data delivery between satellites. Simulation results demonstrate that the proposed INTERLINK can reduce both handover times and average propagation delay compared with its counterparts. Meanwhile, benefitting from integrated DT, both the quality of data delivery and the delay of intersatellite links are considerably improved.

中文翻译：

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INTERLINK：卫星地面网络的数字孪生辅助存储策略


近年来，低轨卫星网络以其覆盖范围广、传输时延低、存储计算能力强等特点受到社会广泛关注。为不同地区的用户提供无缝连接被认为是一种有前景的解决方案，特别是在偏远地区和海洋通信方面。然而，当与地面网络组成星地网络联合使用时，卫星移动速度远高于地面终端，会导致单颗卫星的服务不一致，从而导致频繁的卫星切换。而且，由于卫星的动态性和时隙可见性，星间拓扑变化频繁，导致卫星切换时出现环路，从而降低了链路利用率。为了解决这些问题，我们提出了一种星地网络数字孪生辅助存储策略（INTERLINK），该策略利用数字孪生（DT）将卫星网络映射到虚拟空间以实现更好的通信。具体来说，我们首先提出一种面向卫星存储的切换方案，通过考虑卫星有限的接入时间和容量限制来最小化切换频率。然后，制定多目标优化问题，通过遗传算法获得最优卫星。最后，考虑到卫星链路的定时可见性，引入数字孪生辅助星间路由方案，以提高卫星间数据传输的质量。仿真结果表明，与同类技术相比，所提出的 INTERLINK 可以减少切换时间和平均传播延迟。 同时，受益于集成DT，数据传输质量和星间链路时延均得到显着改善。