Group-based windows scheduling method for non-deterministic periodic flows in time-sensitive networks

Abstract

Time-triggered (TT) flows are usually periodic in time-sensitive networks. However, nondeterministic end systems can generate TT flow frames with significant jitter (i.e., jittery TT flows). Jitter can cause frames to miss the TT windows scheduled for the current period, resulting in excessive access delays, which in turn affect the end-to-end deterministic transmission of the TT flows. In our previous study, we proposed the use of a dynamic multiwindow approach to achieve deterministic access to jittery TT flows; however, its window schedule computation is too slow, and this method is only suitable for small networks with a few TT flows. We therefore propose a group-based, fast scheduling method for accessing and transmitting the windows of jittery TT flows based on multiple windows. A combination of heuristic algorithms and solvers, including the establishment of TT window groups, division of the solution region, and integrated parallel and serial incremental coarse- and fine-grained computations, significantly improves the efficiency of TT window scheduling. For coarse-grained scheduling, by establishing large window clusters and central alignment, the complexity of scheduling is considerably reduced while keeping success rates high. Furthermore, the integer linear programming constraints and objective functions for this method are provided. Compared with the conventional dynamic multiwindow approach, the proposed approach reduces the scheduling time for TT windows by two orders of magnitude for a small star network with a small number of jittery TT flows. Moreover, the reduction in scheduling time becomes more pronounced as the network topology complexity and number of jittery TT flows increase. Finally, the scheduling time performance of the proposed method is verified in commonly used star, tree, and bus networks. Evaluations demonstrate that the access and transmission windows for 500 jittery TT flows can be scheduled in these networks, enabling deterministic access and significantly improving scheduling efficiency.