Details of Research Outputs

Tracking mobile targets in wireless sensor networks (WSNs) is of utmost importance in surveillance applications. As it is often the case in prior work that the accuracy of tracking heavily depends on high accuracy in localization or distance estimation, which is never perfect in practice. These bring a cumulative effect on tracking (e.g., target missing). Recovering from the effect and also frequent interactions between nodes and a central server make tracking operation slow and energy-inefficient. Inspired by these, we design a tracking scheme, called t-Tracking, to address the target tracking problem in WSNs considering multiple objectives: low capturing time (e.g., the tracking time required to get around a target in a defined distance), high energy efficiency, and high quality of tracking (QoT). We propose a set of fully distributed tracking algorithms, which answer the query whether a target remains in a “specific area” (called a “face” in localized geographic routing, defined in terms of radio connectivity or local interactions of nodes). When a target moves across a face, the nodes of the face that are close to its estimated movements compute the sequence of the target’s movements and predict when the target moves to another face. The nodes answer queries from a mobile sink called the “tracker,” which follows the target along with the sequence. t-Tracking has advantages over prior work as it reduces the dependency on requiring high accuracy in localization and the frequency of interactions. It also timely solves the target missing problem caused by node failures, obstacles, etc., making the tracking robust in a highly dynamic environment. We validate its effectiveness considering the multiple objectives in extensive simulations and in a system implementation.