Redundancy and Criticality based Scheduling in Wireless Video Sensor Networks for Monitoring Critical Areas

Abstract

Applications for monitoring critical areas, based on Wireless Video Sensor Networks (WVSN), require simultaneously good level of coverage of the entire region of deployment, high frame capture speed and low power consumption in order to increase network lifetime. The question is how to find a tradeoff between these requirements. In this paper, we first propose two new approaches based on the cover set concept to help a node to find its redundancy level which is defined by the cardinality of its cover set. Then, thanks to a model based on behavior functions modeled by quadratic Bezier curves, we link the frame capture speed of video node to its redundancy level and to its criticality which is assigned to a node according to its position in the network. Border node has high criticality while interior one has low criticality. To identify boundary nodes, we propose an algorithm based on Greedy Perimeter Stateless Routing protocol (GPSR). Then, we propose an algorithm to schedule the activity of sensor nodes according to the redundancy level and criticality of each node. Finally, we introduce a new concept called backward border surveillance based on the cover set approach. Simulation results are presented to show performances of the two proposed approaches in terms of percentage of coverage, number of nodes with cover set, size of this latter, the impact of our scheduling algorithm on network lifetime and the incidence of backward border surveillance concept on quality of surveillance.