A three-tiered topology control model for large scale scale wireless sensor networks

For energy-constrained wireless sensor networks (WSNs), the topology control issue is fundamental and important to maximize the overall network lifetime. Recently a two-tiered network model has been proposed for this purpose. It is a cluster-based network model composed of application and sensor nodes. In this model the application nodes are easy to run out of energy because they not only serve as cluster heads for aggregating data packets from the sensor nodes in their clusters but also are responsible for forming a connected network topology for information dissemination at the higher tier. In order to balance nodes' power consumption and extend the topological lifetime of a WSN with regard to a certain amount of initial energy provision, we propose a logical three-tiered network model which consist of relay nodes(RNs), application nodes(ANs) and sensor nodes(SNs). Under this architecture, the goal of lower-tier SNs is to sense the playing fields and middle-tier ANs only need to gather data from their clusters; Upper-tier RNs are designed to route information as efficiently as possible. In this paper, we first formulate the three-tiered WSN's model as well as the power consumption model of WSNs. Then considering one dimension relaying, we figure out the RNs' optimal placement for each AN which can considerably minimize the total power consumption for WSNs. Finally, we give some criteria for two-dimension relaying.