Time-Sensitive Scheduling Mechanism based on End-to-End Collaborative Latency Tolerance for Low-Earth-Orbit Satellite Networks

Low-Earth-orbit (LEO) satellites are one of the most promising technologies for allowing mobile communication systems to provide ubiquitous network service. However, an LEO constellation can hardly accommodate the kind of time-sensitive service widely required on various Internet-of-Things and industrial Internet-of-Things devices. The limited onboard resources and dynamic constellation topology significantly reduce the robustness of LEO networks and increase the risk of service disruptions. To realize LEO-based time-sensitive networks (TSNs), we introduce a network-layer-based latency-scheduling architecture for LEO satellite networks. The latency-scheduling architecture leverages multi-hop latency optimization instead of optimizing a single node. Based on the cyclic queuing and forwarding (CQF) mechanism usually used in terrestrial networks, we propose a time-sensitive scheduling algorithm (CoLT-TSA) that uses end-to-end collaborative latency tolerance for LEO constellations. CoLT-TSA tries to use the delay redundancy of time-sensitive traffic to improve the scheduling capabilities for TSN flows. The proposed algorithm improves network throughput without affecting the timeliness of time-sensitive services. Moreover, flow contention can be solved by CoLT-TSA based on the collaborative scheduling of satellites along the routing. We conduct simulations to evaluate the proposed algorithm, focusing on the latency, time-out ratio, packet loss and throughput. Various scenarios are simulated for CoLT-TSA and conventional techniques. These extensive simulations indicate that CoLT-TSA can decrease packet loss by more than 2.72% and prevent most of the packet loss of time-sensitive services, as well as reducing the scheduling time-out ratio by more than 4.5% compared to conventional algorithms