Simulative Assessments of Cyclic Queuing and Forwarding with Preemption in In-Vehicle Time-Sensitive Networking

The current automotive industry has a growing demand for real-time transmission to support reliable communication and for key technologies. The Time-Sensitive Networking (TSN) working group introduced standards for reliable communication in time-critical systems, including shaping mechanisms for bounded transmission latency. Among these shaping mechanisms, Cyclic Queuing and Forwarding (CQF) and frame preemption provide deterministic guarantees for frame transmission. However, despite some current studies on the performance analysis of CQF and frame preemption, they also need to consider the potential effects of their combined usage on frame transmission. Furthermore, there is a need for more research that addresses the impact of parameter configuration on frame transmission under different situations and shaping mechanisms, especially in the case of mechanism combination. Firstly, this paper comprehensively reviews the schedulability analysis of the combined usage of CQF and frame preemption based on Compositional Performance Analysis (CPA). This paper summarizes the Worst-Case Responses (WCRs) of streams of each class under CQF with preemption. Secondly, this paper analyses the WCR under CQF with preemption. This analysis identifies the factors that influence the transmission latency for streams of each class and proposes several guidelines in parameter configuration under this mechanism combination. Then, this paper develops a scheduler named CQFP scheduler, enabling the computation of the WCR for all streams under CQF with preemption in different network scenarios. Finally, the paper conducts simulations to obtain the WCR under various configurations, validating the guidelines and the results obtained from the CQFP scheduler. This evaluation provides insights into the performance of the combination of CQF and preemption. The results can provide the network designers detailed guidelines in traffic class assignment and parameter configuration under CQF with preemption.