Lightweight Onboard Routing and Topology Co-Construction for Autonomous GNSSs

Abstract

Global navigation satellite systems (GNSSs) can already plan their inter-satellite link (ISL) topology onboard, leaving routing as the last step toward autonomous networking. In GNSS ISLs, each satellite links to at most one peer per time slot. We exploit this structure to replace end-to-end path search with a single backward sweep over the slots. The proposed method, DS-SMFP, propagates earliest-arrival times backward from each destination and outputs a STORE/FORWARD decision for every slot, satellite, and destination, in time linear in the number of slots and with working memory independent of the planning horizon. Because each slot needs only its own topology and the delivery state of the next one, routing can steer link selection while the topology is built. This slotwise dependency enables Master-Oriented Topology--Routing Co-Construction (MTRCC), which favors traffic to and from a master satellite performing onboard orbit determination. In a 24-h, 30-satellite BeiDou scenario, DS-SMFP matches the delays of Contact Graph Routing (CGR) and shortest path tree (SPT) routing while running over 180 times faster and using over 36 times less peak routing working memory. Compared with fair contact plan (FCP) topology, MTRCC reduces mean master-related traffic delays by over 10\%, with an approximately 3\% increase in mean PDOP. This paper provides a methodological foundation for efficient autonomous GNSS networking.

arXiv comment15 pages, 6 figs