Concurrent moving-based connection restoration scheme between actors to ensure the continuous connectivity in WSANs

In Wireless Sensor-Actor Networks (WSANs), sensors probe the surroundings and forward their data to actors. Actors collaboratively respond to achieve predefined application mission. However, since the environment where WSANs are used is usually complex and harsh, actors cannot communicate with its neighbor actors occasionally due to the failure of an actor. Although the recent work provides a connection restoration scheme between actors, disconnection intermittently occurs since each actor moves to new position one-by-one. In this paper, we propose a concurrent moving-based connection restoration scheme between actors to ensure the continuous connectivity. By sending a message to neighbor actor before moving, an actor can inform when it starts to move and where it moves to. Thus, neighbor actors which receive a message can calculate when it starts to move for concurrent move of actors. An actor starts to move when the communication with neighbor actors is unavailable due to neighbor actor's move. Further, when the actor starts to move, it creates sub-paths to its moving neighbor actor for continuous connectivity. The network restoration time is shortened because of concurrently moving instead of moving one by one. We show that our scheme restores the network connectivity much robuster and faster than the conventional scheme by computer simulation.