Priority-based scheduling of dynamic segment in FlexRay network

FlexRay is an in-vehicle communication network for safety-critical automotive applications such as network-based braking or steering systems. The FlexRay protocol offers various benefits over the existing in-vehicle networks by using a hybrid approach integrating the static segment and the dynamic segment. While the static segment is based on Time Division Multiple Access (TDMA) to achieve deterministic behavior, the dynamic segment adopts so-called Flexible TDMA (FTDMA) to achieve flexible and efficient use of the network. Therefore, scheduling of the dynamic segment in an optimal manner is critical for designing an efficient FlexRay-based system. This paper presents a scheduling method, named Recursive Qualification (RQ), for the dynamic segment in FlexRay. The proposed method is based on the multiple-slot assignment so that the dynamic segment can be used to efficiently transmit the messages with bounded delays. An index of Bus Accessibility (BA) is also adopted to determine the priority of each node. The effectiveness of the proposed method is verified through a set of experiments.