Cluster head placement in Wireless Sensor Network for reliable connectivity and lifetime extension
A novel method of locating Cluster Heads in a Clustered Wireless Sensor Network is proposed to achieve longer lifetime while maintaining reliable connectivity. The network lifetime is increased by reducing the required minimum transmission range of the sensors. The reduction in the transmission range is achieved by inserting high powered Cluster Heads at intermediate strategic locations. The reduced transmission range of nodes decreases the operating power levels of the individual sensors. Consequently, the overall lifetime of the Wireless Sensor Network is extended. Forming appropriate clusters and then calculating the location of the Cluster Head within each cluster is the main objective of this paper. Maintaining a higher degree of network connectivity and operating the sensors at lowered transmission range are conflicting objectives by their very nature. When the transmission range of sensors is reduced, the network connectivity may be lost depending on the network topology and the geographical locations of the sensor. To overcome this problem, we insert Cluster Heads at calculated optimal locations to provide good connectivity while lowering the transmission range of Sensor. To achieve this goal, we introduce smallest_circle function which uses constrained nonlinear programming function fmincon of Matlab. We also propose a new iterative clustering algorithm that solves the absolute minimum p-center minimax facility location problem.