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Recently a barrier-coverage in wireless sensor networks (WSN), which detects a moving object from one side to another opposite side, has attracted lots of attention. Although it is highly desirable to consider a barrier-coverage which can detect any moving objects for multiple sides simultaneously in event-driven environment, an existing barrier does not support those properties. In this paper, we introduce a new type of barrier, event-driven partial barrier, which can detect or monitor every movement of mobile objects on paths among multiple hubs in event-driven environment. Based on the new barrier concept, we define k-EP barriers that a motion by mobile objects is guaranteed to be detected by at least k sensors. Also, we formally define a problem whose objective is to minimize the number of sensors in order to construct k-EP barriers for every hub. To solve the problem, we propose two novel approaches to maximize a network lifetime by minimizing the number of sensors with satisfying requirements of k-EP barriers. Then, we evaluate their relative performances through extensive simulations. |
