Energy neutral clustering for energy harvesting wireless sensors networks.

For wireless sensor networks with energy harvesting capabilities, it is possible to achieve perpetual network operation by maintaining every sensor in the network in an Energy Neutral state. In this paper, a distributive Energy Neutral Clustering (ENC) protocol is proposed to group the network into several clusters, with the goal of providing perpetual network operation. ENC employs a novel Cluster Head Group (CHG) mechanism that allows a cluster to use multiple cluster heads to share heavy traffic load. This CHG mechanism can help to reduce the frequency of cluster re-formations, which in turn reduces the control message overhead. The optimum number of clusters that maximizes the amount of information gathered from the network is mathematically derived using convex optimization techniques. Based on this optimum number of clusters, an extension to ENC is proposed to group the network into equal sized clusters so that maximized network information gathering can be achieved. Extensive empirical studies show that our proposed protocol can successfully prevent sensors from shutting down due to the excessive usage of energy, which in turn provides perpetual network operation with consistent data delivery. Substantial improvements on the amount of information gathered from the network can also be achieved by using our proposed protocol as compared to traditional clustering protocols.