Date Added: Oct 2012
The nodes in Wireless Sensor Networks (WSNs) are usually powered by batteries with finite capacity and one design challenge in sensor networks is to save limited energy resources to prolong the network lifetime. Moreover, the definition of Quality of Service (QoS) and the metrics to evaluate the performance of wireless sensor network are different from traditional networks. There are different Metrics for quality of service in wireless sensor networks and most of them are application-dependent. One of the most important of them is the number of active nodes. Regarding the sensors redundancy, the authors can improve the network lifetime by activating enough number of nodes and making the others sleep. Also, proposing a method that uses the nodes energy equally can prolong the network lifetime.