Energy effective target coverage WSNs

In commercial development and research the growth of Wireless sensor networks are very fast. Target coverage is one of the most active areas of research in wireless sensor networks. Coverage in wireless sensor networks is usually defined as a measure of how well and how long the sensors are able to observe the physical space. Several nodes deployments and design based has been developed depending upon the requirement of the applications and requirements. The deployment of node is generally application based either deterministic or randomized but in both cases target coverage is impotent issue in WSNs. The different placement techniques available in wireless sensor networks. In this paper we address the problem like minimum number of sensors required to construct cover the total area with a given required lifetime of the sensors. In this paper we discuss the problem minimum number of nodes needed to construct energy efficient network and what is the corresponding placement scheme used in field.