A clustering mechanism with various cluster sizes for the sensor network

One of the most important issues on the sensor network with resource-limited sensor nodes is prolonging the network lifetime by effectively utilizing the limited node energy. The most representative mechanism to achieve a long-lived sensor network is the clustering mechanism which can be further classified into the single-hop mode and the multi-hop mode. In the single-hop mode, all sensor nodes in a cluster communicate directly with the cluster head (CH) via single hop, so the contention-less MAC protocol is preferred. In the multi-hop mode, sensor nodes communicate with the CH with the help of other intermediate nodes and the contention-less MAC protocol is not required. One of the most critical factors that impact on the performance of the existing multi-hop clustering mechanism (in which the cluster size is fixed to some value, so we call this the fixed-size mechanism) is the cluster size and, without the assumption on the uniform node distribution, finding out the best cluster size is intractable. Since sensor nodes in a real sensor network are distributed non-uniformly, the fixed-size mechanism may not work best for real sensor networks. Therefore, in this paper, we propose a new dynamic-size multi-hop clustering mechanism in which the cluster size is adjusted according to the information on the load and the residual energy of a CH and that of other nodes near to the CH. We show that our proposed scheme outperforms other clustering mechanisms by carrying out simulations.