Timing Analysis of TDMA-Based Networks Using Network Calculus and Integer Linear Programming

摘要

For distributed safety-critical systems, such as avionics and automotive, shared networks represent a bottleneck for timing predictability, a key issue to fulfill certification requirements. To control interferences on such shared resources and guarantee bounded delays, the Time Division Multiple Access (TDMA) protocol is considered as one of the most interesting arbitration protocols due to its deterministic timing behavior and fault-tolerance features. This paper addresses the problem of computing the worst-case end-to-end delay bounds for traffic flows sharing a TDMA-based network using Network Calculus. First, we extend classic timing analysis to integrate the impact of non-preemptive message transmission and various service policies in end-systems, e.g., First In First Out (FIFO), Fixed Priority (FP) and Weighted Round Robin (WRR). Afterwards, the proposed models are refined using Integer Linear Programming (ILP) to obtain tighter end-to-end delay bounds. Finally, this general analysis is illustrated and validated in the case of a TDMA-based Ethernet network for I/O avionics applications. Results show the efficiency of the proposed models to provide stronger guarantees on system schedulability, compared to classic models.