Message scheduling with reduced matrix cycle and evenly distributed sparse allocation for time-triggered CAN

Controller Area Network (CAN) was initially developed as an in-vehicle real-time communication bus. Due to its low cost and high reliability, it has also become a widely accepted standard in industrial distributed control applications. The CAN protocol has an event-triggered architecture. Although its priority based medium access mechanism provides guaranteed immediate access for the highest priority messages, it may cause unpredictability in communication media for the lower priority messages. In order to address the problems caused by the event-triggered architecture, different time-triggered network architectures, such as TTP, Byteflight, and Flexray, have been introduced.This paper focuses on time-triggered CAN (TTCAN), which is built on the existing CAN standard with the addition of time division multiple access (TDMA). In order to combine the advantages of the event-triggered and time-triggered communication to meet the requirements of the distributed real-time systems, it is crucial to construct feasible message schedules. In this study, a schedule construction method, based on the reduced matrix cycle and evenly distributed sparse allocation, is introduced to produce the best optimum message schedules possible in terms of the message delay performance. The simulation results show that the method introduced in this study provides significant performance improvement not only for the time-triggered messages but also for the event-triggered messages.