A shortest-path tree approach for routing in space networks

A new space era is bringing deployments of thousands of networked assets in near-Earth and deep-space. Delay-Tolerant Networking (DTN) protocols and algorithms such as Contact Graph Routing (CGR) are state-of-the-art technologies certainly capable of achieving this ambitious objective. Nevertheless, in this paper, we highlight and analyze the roots of current scalability limits of CGR, to then propose more efficient alternatives. In particular, we leverage a different graph modeling approach that enables optimizations such as priority queues and spanning-tree searches in the core route determination process. While such abstract data types are difficult to adapt to CGR, we incorporate them into a novel Shortest-Path Tree Approach for Routing in Space Networks (SPSN), which is presented as a compute-efficient alternative. This paper thoroughly describes the SPSN approach including route object modeling, capacity-oriented search, and potential route management techniques. Prototype evaluations analyzed in this paper present significant evidence that SPSN outperforms legacy CGR in more than an order of magnitude in contact plans comprising thousands of contacts.