An effective approach for tolerating simultaneous failures in wireless sensor and actor networks

Wireless Sensor and Actor Networks (WSANs) engage mobile nodes with actuators to respond to certain events in inhospitable environments. The harsh surroundings make actors susceptible to failure. Tolerating occasional actor failure is very important to avoid degrading the performance. In some cases, multiple actors simultaneously fail which makes the recovery very challenging. In this paper, we propose a new recovery approach which can handle simultaneous failures in WSANs. The approach is based on ranking network nodes relevant to a pre-assigned root actor. Ranking creates a tree to be used for coordinating the recovery among nodes. To minimize the recovery overhead, the nodes are virtually grouped to clusters and each node is assigned a recovery weight as well as a nearby cluster member which serves as a gateway to lost nodes. Designation of cluster heads is based on the number of children in the recovery tree. The simulation results confirm the correctness and effectiveness of the proposed approach in restoring network connectivity and also show that on the average the incurred overhead is low compared to contemporary single-failure recovery approaches.