Efficient Sleep Scheduling for Avoiding Inter-Cluster Interference in Wireless Sensor Networks

Clustering sensor nodes is an effective method for achieving high energy efficiency and flexible data aggregation in wireless sensor networks. However, scheduling all clusters to avoid the inter-cluster interference and meanwhile send all observation to the sink quickly is a difficult problem. In this paper, we use interference graph to model the inter-cluster collision problem and propose an efficient sleep scheduling mechanism in the clustered wireless sensor networks. We firstly divide the clusters into layers, then transform the cluster-tree network into the interference graph of clusters, and thereby divide all clusters on one layer into different independent sets. All clusters in the same independent set can work simultaneously without interference, while all independent sets are scheduled one by one for collision-free. To reduce the total delay of data report in the whole network, we propose three kinds of rules to sort the independent sets. Simulation and analysis show that the degree-based sorting rule works best. The practical experiments also verify this conclusion.