FlexRay switch scheduling — A networking concept for electric vehicles

It is projected that the communication data volume in electric vehicles will significantly increase compared to state-of-the-art vehicles due to additional functionalities like x-by-wire and safety functions. This paper presents a networking concept for electric vehicles to cope with the high data volume in cases where a single FlexRay bus is not sufficient. We present a FlexRay switch concept that is capable of increasing the effective bandwidth and improving the safety of existing FlexRay buses. A prototype FPGA implementation shows the feasibility of our approach. Further, a scheduling approach for the FlexRay switch that obtains the optimal results based on Integer Linear Programming (ILP) is presented. Since the ILP approach becomes intractable for real-world problems, we present a heuristic three-step approach that determines the branches of the network, performs a local scheduling for each node, and finally assembles the local schedules into a global schedule. Test cases and an entire realistic in-vehicle network are used to emphasize the benefits of the proposed approach.