Restoring connectivity in Wireless Sensor-Actor Networks with minimal node movement

In Wireless Sensor-Actor Networks (WSANs), sensors probe their surroundings and send their data to more capable actor nodes in order to execute an application task. The actors´ response is mostly collaborative and requires them to coordinate their operation. Therefore, a strongly connected inter-actor topology would be necessary at all time and tolerance of an actor failure becomes a design requirement. Autonomous repositioning of actor nodes has been deemed as an effective recovery strategy. This paper presents a Least-Movement Topology Repair (LeMoToR) algorithm. LeMoToR is a distributed scheme that relies on the local view of a node about the network. To restore connectivity, LeMoToR strives to relocate the least number of nodes and reduce the traveled distance and message complexity. Unlike contemporary schemes that maintain 1 or 2-hop neighbor lists, LeMoToR utilizes existing path discovery activities in the network in order to know the structure of the topology and avoids imposing additional pre-failure communication overhead. The simulation results validate the effectiveness of LeMoToR.