Message Scheduling for the FlexRay Protocol: The Static Segment

• Published in: IEEE transactions on vehicular technology Vol. 58; no. 5; pp. 2170 - 2179
• Main Authors: Schmidt, K., Schmidt, E.G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access methods and protocols, osi model; Algorithms; Applied sciences; Bandwidth; Computer programs; Constrictions; Exact sciences and technology; FlexRay; Integer linear programming; Integer programming; Jitter; Linear programming; Measurement; Messages; Nonlinearity; Organization and planning of networks (techniques and equipments); Organization, operation and development plans; Processor scheduling; Protocol; Protocols; Radiocommunications; real time; Scheduling; Segments; Signal processing; Software architecture; Studies; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Time factors; Transmission and modulation (techniques and equipments); vehicular communication networks; Performance evaluation; Transmission protocol; Jitter; Linear programming; Scheduling; Non linear programming; Bandwidth allocation; Periodic signal; Case study; Integer programming; Trigger; Telecommunication system; Telecommunication network; FlexRay; vehicular communication networks; Software; Metric; Planning; Resource management; Comparative study; real time
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2008.2008654

In recent years, time-triggered communication protocols have been developed to support time-critical applications for in-vehicle communication. In this respect, the FlexRay protocol is likely to become the de facto standard. In this paper, we investigate the scheduling problem of periodic signals in the static segment of FlexRay. We identify and solve two subproblems and introduce associated performance metrics: (1) The signals have to be packed into equal-size messages to obey the restrictions of the FlexRay protocol, while using as little bandwidth as possible. To this end, we formulate a nonlinear integer programming (NIP) problem to maximize bandwidth utilization . Furthermore, we employ the restrictions of the FlexRay protocol to decompose the NIP and compute the optimal message set efficiently. (2) A message schedule has to be determined such that the periodic messages are transmitted with minimum jitter . For this purpose, we propose an appropriate software architecture and derive an integer linear programming (ILP) problem that both minimizes the jitter and the bandwidth allocation . A case study based on a benchmark signal set illustrates our results.