Scheduling Strategy in Fault Tolerant Time Triggered Architectures

Reliable safety critical systems are designed for fault tolerance and impose high dependability with reliability requirements. Scheduling such systems is hard in traditional event triggered systems and becomes difficult as complexity increases. Time triggered systems with timing guaranteed in task activation, avoiding the risk of missing a hard-critical deadline, overcoming the problem of time predictability. As time triggered pattern is going to take control in safety critical applications, gradually scheduling strategies to be more robust and optimal in resource allocation. Previous work has been on handling the schedule of messages within the time triggered protocol for a given TDMA configuration. The sequence and size of slots in a TDMA round are resolved to reduce the delay. Greedy heuristic and meta-heuristics like Simulated Annealing, Genetic algorithms etc., are investigated for better optimization. The Greedy Algorithm works on arriving at global optima by selecting a local optimum. The worst case here is the visit of all the nodes for best possible solution. Randomly each member is selected from the neighborhood in the simulated annealing process, thereby determining the movement to next state. Simulated Annealing parameters make easy in finding near-optimal solutions within a reasonable time. The selection, crossover and mutation, are the fundamental genetic operations of Genetic Algorithm used to modify the solution to obtain appropriate resultant offspring passing on features to succeeding generations. Genetic Algorithm scheduling in fault tolerant time triggered architectures show significant performance improvement when nodes are large in number and guaranteed for optimal solution.