Network hierarchical structure is divided into clusters,
and each cluster is composed of a cluster head and a
plurality of cluster members,and the cluster head to form a
network. A high level of the network can be formed at a
higher level of network clustering. In the cluster head nodes
and cluster member changes, is still the automatic network,
composed of cluster head nodes are responsible for data
forwarding among clusters. Hierarchical structure according
to the different hardware configuration and can be divided
into single frequency and multi-frequency hierarchical
classification, as shown in figure 3.