International Journal of Control and Automation Vol. 8, No. 2 (2015), pp. 232-250 http://dx.doi.org/10.14257/ijca.2015.8.2.24 ISSN: 2005-4297 IJCA Copyright ⓒ 2015 SERSC Greedy Algorithms for Target Coverage Lifetime Management Problem in Wireless Sensor Networks Babacar Diop, Dame Diongue and Ousmane Thiaré Department of Computer Science Faculty of Applied Sciences and Technology University Gaston Berger, BP. 234 Saint-Louis, Senegal babacardiop96@yahoo.fr,{ddiongue.ep2112812,ousmane.thiare}@ugb.edu.sn Abstract When several low power sensors are randomly deployed in a field for monitoring targets located at fixed positions, managing the network lifetime is useful as long as replacing battery of dead sensors is not often feasible. The most commonly investigated mechanism for coverage preserving while maximizing the network lifetime is to design efficient sleep scheduling protocols, so that sensors can alternate their state between being active or not. Maximizing lifetime of a sensor network while satisfying a predefined coverage requirement is an optimization problem, which most of times cannot be optimally solved in polynomial time. In this paper, we address this problem by using set cover approach. We propose a greedy algorithm that distributes sensors among disjoints and non-disjoints set covers with the requirement that each set cover satisfies full targets coverage. The algorithm is an improvement of the classical greedy set cover algorithm, and its approximation ratio is verified to be not worse than (). Simulation results show good performance over some other solutions found in the literature. We provide also a comparison of several greedy techniques found in the literature addressed in the context of different design choices linked to the target coverage problem. Keywords: Target coverage, greedy algorithms, wireless sensor networks 1. Introduction Wireless sensor networks (WSN) are systems of small, low-power networked sensing devices, often deployed over an area of interest (AoI) for monitoring events and/or performing application specific tasks in response to the detected events. Coverage problem is one of the fundamental issues in wireless sensor networks. It essentially refers to how well the sensors observe the physical area. Coverage problems in the literature of WSN can be categorized into three classes [18]: area coverage (the objective is to monitor each location within an AoI with at least one sensor), target coverage (which aims to monitor or track a discrete set of targets points in a sensing field) and barrier coverage (which focus on minimizing the probability of undetected intrusion in a barrier constructed by a sensor network). An important part of the study of coverage in WSN is devoted to target coverage. Target coverage application echoes in various fields (military, medical, industrial) where the studied subjects (military target, medical patient) can be observed or tracked by nearby sensors, embedded or attached on it. In this paper we address the target coverage problem in the context of target coverage application. We assume that several sensors equipped with limited energy