Timing Analysis of TDMA-based Networks using Network Calculus and Integer Linear Programming

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

Performance optimization of a UWB-based network for safety-critical avionics

To reduce the aircraft weight and maintenance costs while guaranteeing system performance and reliability, an alternative avionic communication architecture based on Ultra Wide Band (UWB) and TDMA protocol is proposed to replace the back-up part of safety-critical avionics network. The analysis and performance optimization of such a proposal is tackled as follows. First, appropriate system modeling and timing analysis, using Network Calculus and Integer Linear Programing (ILP) approach, are provided to evaluate the end-to-end delays and verify system predictability. Then, an optimization approach to find the optimal TDMA cycle duration, which minimizes the end-to-end delays, is proposed. Finally, the efficiency of our proposal to enhance the system performance is validated through a realistic avionic case study