Abstract

Upstart space companies are building massive constellations of low-flying satellites to provide Internet service. These developments comprise “one giant leap” in Internet infrastructure, promising global coverage and lower latency. However, fully exploiting the potential of such satellite constellations requires tackling their inherent challenges: thousands of low-Earth orbit (LEO) satellites travel at high velocities relative to each other, and relative to terrestrial ground stations. The resulting highly-dynamic connectivity is at odds with the Internet’s design, which assumes a largely static core infrastructure. Virtually every aspect of Internet design — physical interconnection, routing, congestion control, and application behavior — will need substantial rethinking to integrate this new building block.

In this talk, I will focus on topology design, while also briefly touching upon the other open networking challenges in this context. Coming to topology design, we posit that the high density of these new constellations and the high-velocity nature of such systems render traditional approaches for network design ineffective, motivating new methods specialized for this problem setting. We propose one such method, explicitly aimed at tackling the high temporal dynamism inherent to low-Earth orbit satellites. We exploit repetitive patterns in the network topology to avoid expensive link changes over time, while still providing near-minimal latencies at nearly 2× the throughput of standard past methods.

I will also present Hypatia, a framework for simulating and visualizing LEO networks, that we built to enable broader research in this area. Using publicly available design details for the upcoming networks to drive our framework, we characterize the expected behavior of these networks, including latency and link utilization fluctuations over time, and the implications of these variations for congestion control and routing.