Worst-case response time of aperiodc message in WorldFIP and its improvement in real-time capability

How to support real-time traffic of aperiodic messages using WorldFIP is investigated in this paper. Transmission of aperiodic message within WorldFIP is a very complicated procedure because it is concerned with left time in a microcycle and must successively experience three different stages, indicating, identifying, and transmitting aperiodic message. This paper presents an integrated approach to analyze the worst-case responding time (WCRT) of aperiodic message, through integrating transmission of periodic message and these three stages of aperiodic message together. To decrease pessimistic factors in WCRT of aperiodic message, priority of aperiodic message is considered. Detail analysis of the WCRT of aperiodic message indicates that the current scheduling method cannot effectively utilize priority to guarantee important aperiodic messages. Then improved scheduling methods, one adding priority and another adjusting the schedule table, are proposed. The improved methods are finally validated by case studies.