Slow-Shot-Based Routing Selection for Optical Satellite Networks with Dynamical Optical Inter-Satellite Links

Optical satellite networks (OSNs) based on low-Earth-orbit (LEO) satellites and optical inter-satellite links (ISLs) are considered a promising component of future high-capacity space communications. However, the high mobility of LEO satellites leads to frequent changes in satellite–ground connectivity, which may cause interruptions in end-to-end optical paths and increase routing instability. To mitigate the impact of frequent satellite–ground handovers, in this paper we investigate routing selection problems for two categories of services with different temporal requirements, namely real-time and time–torrent services. First, a real-time and time–torrent service routing (RTSR) problem was established based on the relevant network and service models. Second, a slow-shot topology model was developed to represent the time-varying network topology through a sequence of snapshots. Third, two routing algorithms, namely slow-shot-based routing selection (SS-RS) and multi-delivery parallel SS-RS (MSS-RS), were proposed to accommodate different service requirements in the time and capacity dimensions, respectively. Extensive simulations were conducted to evaluate the proposed algorithms in terms of their service blocking probability, delivery interruption ratio, bandwidth utilization, and average hop count. The results illustrate the effectiveness of the algorithms, while exhibiting trade-offs regarding service blocking, resource utilization, and routing performance.