Intersatellite Links: Lower Layer Protocols for Autonomous Constellations

In order to have autonomous formation-flying satellite constellations in low earth orbit LEO, the satellites in the constellation must be able to communicate with each other directly via intersatellite links ISLs. Current ISL implementations use lower layer link protocols based on existing networking protocols such as X.25 and LAP-B, which were not designed specifically for ISL use. This paper compares current and upcoming lower layer protocols in an attempt to identify a protocol for widespread ISL use such that interaction among different constellations is possible and the addition of new satellites to existing constellations is simpler.