SKYCASTLE: Taming LEO Mobility to Facilitate Seamless and Low-latency Satellite Internet Services¶

Abstract¶

Abstract—Emerging integrated space and terrestrial networks (ISTN) built upon low earth orbit (LEO) satellite constellations aim at providing planet-wide Internet services, not only for residential users, but also for mobile users (e.g., in airplane and cruise scenarios). Efficiently managing global mobility and keeping connections active for mobile users is critical for ISTN operators. However, our quantitative analysis identifies that existing mobility management (MM) schemes suffer from frequent connection interruptions and long latency in ISTN scenarios. The fundamental challenge stems from a unique characteristic of ISTNs: not only users are mobile, but also core network infrastructures (i.e., LEO satellites) are frequently changing their locations in the network.

To facilitate seamless and low-latency satellite Internet services, this paper presents SKYCASTLE, a novel network-based global mobility management mechanism. SKYCASTLE incorporates two key techniques to address frequent connection interruptions in ISTNs. First, to reduce the interruption time, SKYCASTLE adopts distributed satellite anchors to track the location changes of mobile nodes, manage handovers and avoid routing convergence. Second, SKYCASTLE leverages an anchor manager to schedule MM functionalities at satellites to reduce deployment costs while guaranteeing low latency. Extensive evaluations combining real constellation information and mobile user trajectories show that: SKYCASTLE can improve up to 55.8% uninterrupted time and reduce 47.8% latency as compared to other existing MM solutions.

Index Terms—Integrated Space and Terrestrial Networks, Satellite Internet Services, Global Mobility Management.

基于低地球轨道（LEO）卫星星座构建的新兴集成空间与地面网络（ISTN）旨在为全球提供互联网服务，不仅面向居民用户，还包括移动用户（如飞机和游轮场景中的用户）。有效管理全球移动性并保持移动用户连接的持续性对于ISTN运营商至关重要。然而，我们的定量分析表明，现有的移动性管理（MM）方案在ISTN场景中存在频繁连接中断和较长延迟的问题。其根本挑战源于ISTN的一个独特特征：不仅用户是移动的，核心网络基础设施（即LEO卫星）也频繁改变其在网络中的位置。

为了实现无缝且低延迟的卫星互联网服务，本文提出了SKYCASTLE，一种新型的基于网络的全球移动性管理机制。SKYCASTLE通过两项关键技术来解决ISTN中频繁连接中断的问题。

首先，为了减少中断时间，SKYCASTLE采用分布式卫星锚点来跟踪移动节点的位置变化，管理切换并避免路由收敛。

其次，SKYCASTLE利用锚点管理器调度卫星上的移动性管理功能，以减少部署成本，同时保证低延迟。结合真实星座信息和移动用户轨迹的广泛评估表明：与其他现有的移动性管理解决方案相比，SKYCASTLE能够提高最多55.8%的无中断时间，并减少47.8%的延迟。

关键词 —— 集成空间与地面网络，卫星互联网服务，全球移动性管理。