Energy-efficient cooperative MIMO routing in wireless sensor networks

Due to limited batteries of senor node in wireless sensor networks, it is essential to minimize the energy consumption so that the lifetime of WSNs can be prolonged. In this paper, we propose a cooperative multi-input multi-output (CMIMO) scheme by introducing variable cluster size. In general, if the same cluster size is applied in each cluster, the cluster head with lower residual energy runs up more quickly than those with more residual energy. This may result in reclustering in which process new cluster head has to be re-selected. Lots of energy is consumed in this process. In order to avoid energy waste in reclustering, we consider the trade off between residual energy of cluster head and cluster size in cluster construction. We compute the maximized cluster size on the basis of residual energy of cluster head. The cluster with more residual energy has bigger cluster size and the cluster with less residual energy has smaller cluster size. This can balance the energy consumption in each cluster. We analyze the mathematical model for the proposed scheme. It is shown that the proposed scheme is more energy efficient than existing schemes. In our energy model, we present how to determine the cluster size and justify our method by simulations.