Trust Based Node Scheduling Protocol for Target Coverage in Wireless Sensor Networks

Wireless sensor networks are often deployed in decision making infrastructures such as battlefield monitoring systems and Supervisory Control and Data Acquisition Systems (SCADA), to perform sensing operations and communication between sensors to report the occurrence of various events to a central processing unit known as Base station. These networks are usually resource constrained in terms of transmission power, bandwidth and memory. Uncertainty and dynamics of the communication channel such as noise interference, signal fading and irregular terrains pose a challenge in the detection and reporting of the events. Undetected or incorrectly reported events reduce the quality of coverage. To overcome these limitations trust mechanisms are incorporated. In this paper we propose a trust based node scheduling protocol for target coverage which considers the uncertainty of the nodes’ opinion in the calculation of trust by using the subjective logic framework. The base station determines the schedule of nodes to keep in active state on the basis of coverage probability and trust values. For the calculation of the trust we have used the data and energy trust in addition to the communication trust. Whenever the direct communication is not available between two nodes, the recommendation trust or indirect trust is used. The recommender node’s reliability and familiarity is also considered. The trust calculation based on several metrics increases the reliability of the data reported. As the energy level of the node is also considered, so the proposed mechanism improves the network lifetime with improved quality of data trust, while providing the coverage of all the targets.