Date Added: Feb 2013
A Wireless Sensor Network (WSN) is a network that is composed of large number of low cost, low power sensor nodes that are interconnected by means of wireless medium and it finds major application in the field of environment monitoring, target tracking, vehicle tracking and surveillance. The unique characteristics of WSNs such as limited bandwidth, computing capacity, data delivery delay and severe energy constraints make their design more challenging. A critical issue in wireless sensor networks is the limited availability of energy and many researches are carried out to for optimizing energy. The best way to improve the network lifetime is by turning the node on/off as per the functionalities.