A key management scheme for dividing/merging cluster based wireless sensor networks

Wireless sensor networks are one of the pioneer technologies of the new century. The low cost of these networks makes them applicable to a variety of areas from battlefields and environment monitoring to health and house applications. A sensor network is composed of a large number of low cost sensor nodes densely deployed for a specific application inside a usually small environment. Due to its dynamic nature, it might be necessary to change the objective of the network or enhance its total configuration with adding or deleting some nodes after any deployment. Dividing a sensor network into two or merging two networks is examples of these modifications. The aim of this paper is to consider these modifications in a cluster based sensor network. In this paper, we propose two methods, one for dividing a network into two independent networks and the other for merging two independent ones into a whole network. In order to divide a network, we assign a new command node for the network and transfer the information of keys, gateways and nodes to be used for a series of messages exchanged between these elements. Then, the new command node is responsible for a portion of the first network, which is in fact a separate network. Also for merging two networks, we transfer the data base of command node of one network into another and eliminate the said command node and inform its gateways of the existence of a new manager. Simulation results show the applicability of the proposed method. We simulate the network division and combination for different number of gateways transferred or added to a cluster based sensor network consisting of sensor nodes and gateways.