Minimizing the Number of Clusters in IEEE 802.15.4 Wireless Sensor Networks

Traditionally, in IEEE 802.15.4 wireless sensor networks (WSN), cluster trees are constructed by connecting cluster heads. Though this way may reduce the number of routers, excess clusters may cause extra data transmission delay and will reduce the collection efficiency of sensing data. In this paper, we proposed a method that can effectively reduce the data transmission delay by minimizing the number of clusters in IEEE 802.15.4 WSN. Bridges are used to connect two cluster heads to perform a two-hop transmission in one cluster active time slot. Moreover, based on the idea of the maximum independent set in a tree cluster, heads, bridges, and leaf nodes can be properly assigned to construct a cluster tree that can minimize the number of clusters. The simulation results showed the proposed method can effectively reduce the total number of clusters up to 40% than the previous work. As a result, the average delay time of IEEE 802.15.4 wireless sensor networks can be reduced significantly.