Incremental Scheduling of the Time-triggered Traffic on TTEthernet Network

Complex systems are often developed incrementally when subsequent models must be backward compatible with the original ones. The need to exchange high-volume data, for example, multimedia streams in the avionic systems, together with safety-critical data, puts demands on both the high bandwidth and the deterministic behavior of the communication. TTEthernet is an Ethernet based protocol that enables the transmission of the time-triggered messages. Thus, synthesizing a good schedule that meets all the deadline requirements and preserves the backward compatibility with the schedules of preceding models is essential for the performance of the whole system. In this paper, we study the problem of designing periodic communication schedules for time-triggered traffic. The aim is to maximize the uninterrupted gap for the remaining non-deadline-constrained traffic. The provided scheduling algorithm, based on MILP and CP formulation, can obtain good schedules in a reasonable time while preserving the backward compatibility. The experimental results show that the time demands of the algorithm grows exponentially with the number of messages to be transmitted, but, even for industrial-sized instances with more than 2000 messages, the algorithm is able to return the close optimal schedules in the order of hundreds of seconds.