Distributed On-Demand Routing for LEO Mega-Constellations: A Starlink Case Study

TL;DR

This paper introduces a formal model and an on-demand routing algorithm for LEO mega-constellations, specifically Walker Delta formations, to efficiently compute near-optimal routes with reduced delay and resource use.

Contribution

It presents a novel formal model for satellite positions in Walker Delta constellations and an on-demand hop-count routing algorithm that outperforms classical methods.

Findings

The model accurately captures satellite positions over time.

The routing algorithm achieves lower latency than Dijkstra.

It reduces computational complexity for large constellations.

Abstract

The design and launch of large-scale satellite networks create an imminent demand for efficient and delay-minimising routing methods. With the rising number of satellites in such constellations, pre-computing all shortest routes between all satellites and for all times becomes more and more infeasible due to space and time limitations. Even though distributed on-demand routing methods were developed for specific LEO satellite network configurations, they are not suited for increasingly popular mega-constellations based on Walker Delta formations. The contributions of this paper are twofold. First, we introduce a formal model that mathematically captures the time-evolving locations of satellites in a Walker Delta constellation and use it to establish a formula to compute the minimum number of ISL hops between two given satellites. In the second part, we present an on-demand hop-count-based routing algorithm that approximates the optimal path while achieving superior performance compared to classical shortest-path algorithms like Dijkstra.