Low-Earth Orbit (LEO) satellite networks are a key enabler for the 6G Non-Terrestrial Network (NTN) architecture. However, supporting time-sensitive services in LEO networks is challenging due to highly dynamic topologies and the difficulty of maintaining precise global time synchronization. Existing Time-Sensitive Networking (TSN) mechanisms largely rely on static topologies and strict synchronization, which makes them ill-suited to dynamic LEO environments. To address this issue, we propose CRT, a deterministic transmission framework tailored for LEO networks. CRT regulates per-hop residence time using local clocks, thereby compensating for link-delay variations without requiring strict global synchronization. To handle asynchronous collisions, CRT adopts a collision-tolerant scheduling strategy that maximizes the number of schedulable flows while bounding collision-induced jitter. We formalize the corresponding scheduling problem and show that it is NP-hard. We further develop CRT-Fast, an efficient heuristic algorithm. It combines iterative layering with path continuity to control collision intensity and improve path stability under topology changes. Simulations on Iridium and Starlink constellations show that the proposed method achieves lower delay jitter and high schedulability under heavy traffic loads.

翻译：低地球轨道（LEO）卫星网络是6G非地面网络（NTN）架构的关键支撑技术。然而，由于高度动态的拓扑结构以及难以维持精确的全局时间同步，在LEO网络中支持时间敏感业务面临挑战。现有的时间敏感网络（TSN）机制主要依赖静态拓扑和严格同步，难以适应动态的LEO环境。为解决该问题，我们提出CRT——一种专为LEO网络设计的确定性传输框架。CRT利用本地时钟调控逐跳驻留时间，从而无需严格全局同步即可补偿链路时延变化。为处理异步冲突，CRT采用容冲突调度策略，在限制冲突引发抖动的同时最大化可调度流数量。我们对相应调度问题进行形式化建模，并证明其为NP难问题。进一步地，我们开发了高效的启发式算法CRT-Fast。该算法结合迭代分层与路径连续性，以控制冲突强度并提升拓扑变化下的路径稳定性。基于铱星和星链星座的仿真表明，所提方法在重流量负载下可实现更低时延抖动与高可调度性。