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A Stability-first Approach to Running TCP over Starlink

Gregory Stock, Juan A. Fraire, Santiago Henn, Holger Hermanns, Andreas Schmidt

TL;DR

The paper addresses the instability of end-to-end routes in LEO satellite networks and its adverse impact on TCP-like transport protocols. It develops a stability-first approach by proposing four route selection algorithms (Dijkstra, Stubborn, Tenacious, SetCover) and a transport-layer evaluation framework (artCP) to assess how routing decisions affect RTT variability, reordering, and data rate. Through experiments on Starlink-like Walker Delta constellations, the work shows that stability-focused methods can notably improve TCP throughput and reduce disruptive reordering, albeit sometimes at the cost of higher delay, and it advocates co-designing routing with transport control. The results highlight the practical potential of stability-aware orbital routing for reliable, high-performance in-orbit communication and point to future work on broader constellations and validation.

Abstract

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.

A Stability-first Approach to Running TCP over Starlink

TL;DR

The paper addresses the instability of end-to-end routes in LEO satellite networks and its adverse impact on TCP-like transport protocols. It develops a stability-first approach by proposing four route selection algorithms (Dijkstra, Stubborn, Tenacious, SetCover) and a transport-layer evaluation framework (artCP) to assess how routing decisions affect RTT variability, reordering, and data rate. Through experiments on Starlink-like Walker Delta constellations, the work shows that stability-focused methods can notably improve TCP throughput and reduce disruptive reordering, albeit sometimes at the cost of higher delay, and it advocates co-designing routing with transport control. The results highlight the practical potential of stability-aware orbital routing for reliable, high-performance in-orbit communication and point to future work on broader constellations and validation.

Abstract

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.
Paper Structure (11 sections, 1 equation, 4 figures, 1 table)

This paper contains 11 sections, 1 equation, 4 figures, 1 table.

Table of Contents

  1. Introduction
  2. Context & Methodological Framework
  3. Walker Delta Constellations & Orbital Dynamics
  4. Efficiency and Stability Metrics
  5. Route Selection Algorithms
  6. Evaluation and Results
  7. Transport Layer Performance Evaluation Framework
  8. Example: Bariloche and Beijing on Starlink
  9. Aggregated Grid Analysis
  10. Run Time / Computational Complexity
  11. Conclusion

Figures (4)

  • Figure 1: Comparison of end-to-end route delay and validity for the ground station pair Bariloche and Beijing on Starlink.
  • Figure 2: Cumulative statistics of the four algorithms on the ground station pair Bariloche and Beijing on Starlink.
  • Figure 3: artCP results showing the round-trip time and in-flight window (IWND) for the algorithms Dijkstra and Tenacious.
  • Figure 4: CDF plots over aggregated data for points on a latitude/longitude grid for Starlink.