In this paper, we propose an improvement on LEACH (Low Energy Adaptive Clustering Hierarchy) protocol in order to monitor the large-scale environment longer and stably with wireless sensor networks. Since being proposed, the LEACH protocol has been regard as a perfect routing protocol of wireless sensor networks (WSNs) while the system was used to monitor large-scale area, and we have never stop improving this classic routing protocol all the time. There has been lots of improvement on LEACH protocol now such as LEACH-C etc. But nearly all of those advanced protocol based on LEACH protocol continue using a primal function of LEACH to set a fixed optimum number of clusters in each round during the whole lifetime of the system, and the nodes computes their own probability to be cluster head mostly in terms of this optimum number of clusters. In our experiment, we found it will seriously damage the system's lifetime and stability that the nodes reckon the probability to be cluster head relying on the fixed optimum number of clusters. As we known, the nodes will die during the system life; it means the total number of the nodes in network must be decreasing along with the system-life. In the LEACH protocol, we know the optimum number of clusters in each round depend on the total number of the nodes in the network. Theoretically while the total number of the nodes is deceased, the optimum number of cluster should be upgraded too. In this improvement, we introducing a special method which let the system choose the dynamic optimum number of clusters during the system's set-up state, and the dynamic optimum number of clusters were decided base on the real time total sum of nodes in the whole network. As the experiment results shown, the improvement can not only prevent the system from seriously energy consumption, and obviously extend the lifetime but also advance the quality of our monitoring system.
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