Wireless Sensor Network (WSN) is an emerging technology that shows great promise for various futuristic applications both for mass public and military. A wireless sensor node consists of sensing, computing, communication, actuation, and power components. These sensing devices have the opportunity of collaboration amongst themselves to improve the target localization and tracking accuracies. Distributed data fusion architecture provides a collaborative tracking framework. Due to the present energy constraints of these small sensing and wireless communicating devices, a common trend is to put some of them into a dormant state.