Ego-Satellite Perspective Multi-PAT Configurations for Optical Inter-Satellite Links

Abstract

Efforts are being made to commercialize optical inter-satellite links (O-ISL) in low earth orbit (LEO) satellite networks as it is a crucial technology for next-generation communication networks. However, installing the pointing, acquisition, and tracking (PAT) modules is vital due to the long link distances among the fast-orbiting satellites. This research investigates the configurations of multiple PAT modules (multi-PAT) and the tradeoff between data-rate and latency, considering practical constraints such as link distance back-off and the atmospheric bypass. An ego-centric coordinate conversion method facilitates the field-of-view analysis from an ego-satellite perspective optimization of the multi-PAT. Simulation results suggest that around 70% of angular coverage around the ego-satellite through the multi-PAT allows reliable O-ISLs. The link distance back-off constraining the maximum distance of an individual link sensitively governs the number of hops, but the total O-ISL path distance is less affected. Regarding the atmospheric bypass restricting the lowest altitude for each link, the side-effect is insignificant even when the atmosphere up to 100 km from the ground is bypassed. The communication and latency performances are in a tradeoff relationship since the per-link distance and the number of hops are inversely related in O-ISLs. The individual link distance significantly affects the channel loss, and the number of hops directly influences latency. Depending on the multi-PAT configurations, an O-ISL system with ~10 Gb/s within ~200 ms can be established from New York to Seoul.

Keywords

• Optical inter-satellite link
• O-ISL
• optical wireless communication
• OWC
• free-space optical communication
• FSO