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.