A Flexible Slotting Scheme for TDMA-Based Protocols

Popular fault-tolerant TDMA-based protocols like TT-CAN ([Fu00] and [Mu02]), TTP ([KG93]) and FlexRay ([Fl02]) are using a static slotting scheme for bus arbitration. This paper describes a possible solution for a more flexible handling of the slotting, by providing extra time of variable length in the cycle for additional slots. These extra time is only provided if it is requested by the controllers in the network. Another possibility is to configure extra slots statically (to come to a fixed cycle length) and assign the slots dynamically to different controllers. A new node architecture is introduced for improving protection of the bus in case of a faulty controller. An agreement algorithm for determining a new schedule every cycle in the distributed network is presented. The system is capable of tolerating double-faults (one controller and one channel).