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Abstract: |
Wireless sensor network (WSN) is a network consisting of several nodes equipped with sensors that cooperatively monitor physical conditions. WSNs are being used in many monitoring applications. There has been a lot of research on target-tracking in WSNs. Many papers focus on developing prediction algorithms for accurate tracking of the target's path. Other papers focus on developing selective node-activation algorithms that wake up sensors along the predicted path of the target from their sleep-mode, wherein all the nodes in the network are in sleep-mode except the active boundary sensor-nodes. One important criterion is to keep the reporting time to the base-station minimal, so as to enable the monitoring application to provide a timely response. To the best of our knowledge, there is no research work on performing target monitoring with a strict response-time deadline. Response time is the difference between the initial detection-time and the first reporting-time (to the base station). In this report, we present a new approach to perform coordinated activation and reporting for energy-efficient target monitoring (detection, tracking, and reporting) in WSNs. Our approach aims to minimize the response time by activating sensors (from sleep-mode) that are along the target's path and then forwarding the information collected from these sensors on the same path guaranteeing to meet the response-time deadline. But if we are unable to meet the deadline, then we split tracking and reporting, ensuring that reporting to the base station happens within the specified response-time deadline. We perform extensive delay analysis and simulations on different sets of sample target-paths, and compute the response time and network lifetime for each case. We also investigate the optimal base-station placement problem, so as to improve the average response time in the network. Our work focuses on developing an analytical model for each of the scenarios and then verifying them to be accurate using simulations. |
