A Cluster Head Election Method for Equal Cluster Size in Wireless Sensor Network

Wireless sensor networks (WSNs) are composed of many homogeneous or heterogeneous sensor nodes with limited resources. A sensor node is comprised of three components: a sensor, a processor and a wireless communication device. A sensor of nodes detect a change in surroundings, a processor processes sensing data collected from neighbour nodes or own environmental information, and a wireless communication device is capable to send and receive sensing data. Sensor networks consist of a great number of sensor nodes and one or several sink nodes. The role of a sensor node is to detect and process own environmental information, to convert it to sensing data, to send it to neighbour nodes or sink nodes, and to collect it from neighbour nodes. On the other hands, the role of a sink node is to collect sensing data from sensor nodes and to be gateway that interconnects different network and transmits data to it. Generally, sensor nodes of WSNs are randomly scattered on specific area for satisfying user’s requirements (detecting, observing and monitoring environment) and have to selforganized network. It is difficult to exchange and charge node battery as the area where sensor nodes are located in is inaccessible location. So, it is important issue to design powerefficient protocol method for low-power operation and prolonging the network lifetime (Akyildiz et al, 2002). A sensor node needs wireless ad-hoc network capability to collect sensing data of wireless sensor network without a communication infrastructure. Sensor networks are, however, not suitable for the existing ad-hoc routing method (Tubaishat & Madria, 2003) because of sensor nodes with limited capability. Thus sensor networks require wireless ad-hoc routing method considering self-organization, restrictive power, and data-based communication(Sohrabi et al, 2000) and need multi-hop routing mechanism because of the limited transmission radius of a sensor nodes. WSNs should design for routing algorithm considering low-power operation because it has limited features and is a traditional wireless networks completely different from ‘the network(Al-Karaki & A.E. Kamal, 2004). In WSNs, routing methods can divide into two routing mechanisms: ‘flat-routing’ and ‘hierarchical-routing’. The ‘flat-routing’ technique regards the whole network as one region, enabling all nodes to participate in one region. On 10