Timed Automata with Disjoint Activity

The behavior of timed automata consists of idleness and activity, i.e. delay and action transitions. We study a class of timed automata with periodic phases of activity. We show that, if the phases of activity of timed automata in a network are disjoint, then location reachability for the network can be decided using a concatenation of timed automata. This reduces the complexity of verification in Uppaallike tools from quadratic to linear time (in the number of components) while traversing the same reachable state space. We provide templates which imply, by construction, the applicability of sequential composition, a variant of concatenation, which reflects relevant reachability properties while removing an exponential number of states. Our approach covers the class of TDMA-based (Time Division Multiple Access) protocols, e.g. FlexRay and TTP. We have successfully applied our approach to an industrial TDMA-based protocol of a wireless fire alarm system with more than 100 sensors.