Date Added: Oct 2010
The last few years have seen an increased interest in the potential use of Wireless Sensor Networks (WSNs) in various fields like disaster management, battle field surveillance, and border security surveillance as described by Quaritsch (2010), Hart (2006), Bokareva (2006) and Dudek (2009). In such applications, a large number of sensor nodes are deployed, which are often unattended and work autonomously. Clustering is a key technique used to extend the lifetime of a sensor network by reducing energy consumption (Younis 2003). It can also increase network scalability. Researchers in all fields of wireless sensor network believe that nodes are homogeneous, but some nodes may be of different energy to prolong the lifetime of a WSN and its reliability.