Placement of relay nodes in wireless sensor networks

The placement of relay nodes is one of the critical need of wireless sensor networks when connectivity, lifetime, fault tolerance like factors are desired in the network. In this study, we review the node placement techniques based on two broad categories, i.e. algorithm based and approximation based solutions and provide an overall view of this study by summarizing previous achievements. A taxonomy is presented to enlist the present techniques. The paper also emphasizes on the research challenges and gives an idea of potential future scope in this research domain.