Edge (of the Earth) Replication: Optimizing Content Delivery in Large LEO Satellite Communication Networks

Large low earth orbit (LEO) satellite networks such as SpaceX's Starlink constellation promise to deliver low-latency, high-bandwidth Internet access with global coverage. As an alternative to terrestrial fiber as a global Internet backbone, they could potentially serve billions of Internet-connected devices. Currently, operators of CDNs exploit the hierarchical topology of the Internet to place points-of-presence near users, yet this approach is no longer possible when the topology changes to a single, wide-area, converged access and backhaul network. In this paper, we explore the opportunities of points-of-presence for CDNs within the satellite network itself, as it could provide better access latency for users while reducing operational costs for the satellite Internet service providers. We propose four strategies for selecting points-of-presence in satellite constellations that we evaluate through extensive simulation. In one case, we find that replicating web content within satellites can reduce bandwidth use in the constellation by 93% over an approach without replication in the network, while storing just 0.01% of all content in individual satellites.