Efficient failure recovery in Wireless Sensor Networks through active, spare designation

In some applications a sensor network is composed of a set of mobile nodes deployed in an area of interest in order to collectively monitor suspicious activities, perform surveillance tasks, etc. Such collaboration needs frequent inter-node interaction and requires strong network connectivity. A sudden node failure may make nodes unreachable causing the network to partition. In addition, the loss of a node may result in a degraded coverage in certain area, and can thus negatively affect the network operation. Traditional recovery approaches pursue node repositioning upon the detection of the failure in order to reestablish connectivity. Unlike these reactive recovery approaches, this paper argues that some pre-failure planning would facilitate and expedite the recovery process. The idea is to find spare nodes inside a network, prior to the failure that can volunteer to replace the failed node. Identification of spare nodes is done based upon coverage overlap and node degree. A spare node is designated based on the contribution of a node to the network coverage and connectivity. When a failure is detected, the most suitable active spare is called to replace the dead node and the network topology is adjusted through a series of cascaded motion. The proposed approach is validated through simulation.