A study on optimal hierarchy in multi-level hierarchical mobile IPv6 networks

Hierarchical mobile IPv6 (HMIPv6) is an enhanced mobile IPv6 in order to reduce signaling overhead and to support seamless handoff in IP-based wireless/mobile networks. To support more scalable services, HMIPv6 can be organized as a multilevel hierarchy architecture (i.e, tree structure). However, since the multi-level HMIPv6 results in additional packet processing overhead, it is necessary to consider the overall cost and to find the optimal level to minimize the overall cost. In this paper, we investigate this problem, namely the design of a multi-level HMIPv6 with optimal hierarchy. To do this, we formulate the location update cost and the packet delivery cost in the multi-level HMIPv6. Based on the formulated cost functions, we present the optimal hierarchy level in the multi-level HMIPv6 to minimize the total cost. In addition, we investigate the effects of session-to-mobility ratio (SMR) on the total cost and the optimal hierarchy. The numerical results, which show various relationships among network size, optimal hierarchy, and SMR, can be utilized to design an optimal HMIPv6 network.