Effective division and merger of the autonomous clustering scheme for highly mobile large ad hoc networks

The autonomous clustering scheme (shortly, previous scheme) was proposed to construct the hierarchical structure in ad hoc networks. The feature of the previous scheme is that the number of nodes in each cluster is bounded by two constants called upper and lower bounds. If the number of nodes in a cluster exceeds the upper bound, the cluster is divided into two clusters. If the number of nodes in a cluster becomes less than the lower bound, the cluster merges itself with one of its neighboring clusters. However, in the previous scheme, there is some possibility that the number of nodes in the divided cluster becomes less than the lower bound. In this case, it happens that the divided cluster tries to remerge itself with one of its neighboring clusters. Moreover, due to the remerger, the cluster might be divided again. This paper proposes a new autonomous clustering scheme (shortly, proposed scheme) which improved the previous scheme. In the proposed scheme, by using a tree in each cluster, the number of nodes is adjusted so that it becomes between the upper and lower bounds. The experimental results show that the proposed scheme has higher adaptability to node movement than the previous scheme.