Inter-Satellite Link Optimization for Low-Latency Global Networking

TL;DR

This paper introduces a two-stage optimization framework for designing inter-satellite link topologies that minimize network diameter and latency in low-Earth-orbit satellite constellations.

Contribution

It presents a convex relaxation approach combined with integer programming and heuristics to optimize satellite network topologies for low latency and robustness.

Findings

Proposed method reduces network diameter significantly compared to heuristics.

Achieves end-to-end delays under 90 ms for 1,500 satellite constellations.

Demonstrates improved robustness and latency trade-offs in simulations.

Abstract

Large-scale low-Earth-orbit satellite constellations offer a promising platform for global low-latency networking, aided by faster propagation in free space than in fiber and copper. In such systems, end-to-end latency is largely determined by the inter-satellite link (ISL) topology. In particular, the network diameter, the maximum shortest path between any pair of satellites, serves as a key performance metric for time-sensitive applications. Designing diameter-optimal topologies is challenging due to degree constraints, line-of-sight limitations, and orbital dynamics. This paper proposes a two-stage optimization framework for ISL topology design. First, a continuous relaxation of the link selection problem is formulated as a convex program that maximizes the algebraic connectivity of the Laplacian, serving as a tractable surrogate for diameter minimization. Second, the resulting fractional solution is mapped to a feasible discrete topology using integer linear programming. An iterative local-search heuristic is also developed as a baseline. Extensive simulations on Walker-Delta constellations show that the proposed method consistently achieves smaller network diameters and improved robustness compared to conventional heuristics, while allowing trade-offs between latency and link persistence. The approach offers a principled framework for designing high-performance satellite mesh networks. For a constellation of 1,500 satellites, each equipped with four ISLs of up to 2,500 km, the network diameter can be reduced to as low as 12, yielding end-to-end delays under 90 ms between any two points on Earth.