The end-to-end connectivity patterns between two points on Earth are highly volatile if mediated via a Low-Earth orbit (LEO) satellite constellation. This is rooted in the enormous speeds at which satellites in LEO must travel relative to the Earth's surface. While changes in end-to-end routes are rare events in stationary and terrestrial applications, they are a dominating factor for connection-oriented services running over LEO constellations and mega-constellations. This paper discusses how TCP-over-constellations is affected by the need for rerouting and how orbital route selection algorithms impact the end-to-end performance of communication. In contrast to the state of the art that primarily optimizes for instantaneous shortest routes (i.e. lowest delay), we propose several algorithms that have route stability and longevity in their focus. We show that this shift in focus comes with vastly improved end-to-end communication performance, and we discuss peculiar effects of the typical TCP-like implementations, taking inspiration from the Starlink constellation in our empirical investigations. The spectrum of algorithms proposed provides a basis for co-designing suitable orbital route selection algorithms and tailored transport control algorithms.

翻译：若通过低地球轨道卫星星座进行中继，地球表面两点间的端到端连接模式具有高度不稳定性。这源于低地球轨道卫星相对于地表必须维持的巨大运行速度。虽然端到端路由变化在固定地面应用中属于罕见事件，但对于运行在低地球轨道星座与巨型星座上的面向连接服务而言，却成为主导性影响因素。本文探讨了星座网络TCP通信如何受路由重选需求的影响，以及轨道路由选择算法如何影响端到端通信性能。与当前主要优化瞬时最短路径（即最低延迟）的技术方案不同，我们提出了若干以路由稳定性与持久性为核心目标的算法。研究表明，这种目标转向能显著提升端到端通信性能，同时结合Starlink星座的实证研究，我们探讨了典型类TCP实现中的特殊效应。所提出的算法体系为协同设计适宜的轨道路由选择算法与定制化传输控制算法提供了基础。