| Mobility management is one of the most challenging technologies in the heterogeneous/converged network. As an important control functions in support of ubiquitous, heterogeneous mobility management techniques, vertical handoff becomes the focus of study. In the Heterogeneous/Convergence networks, more and more factors, such as the network QoS state, user preferences, prices,.etc, need to be considered. On one hand, it is a problem that how to obtain and manage these factors at different protocol levels to support handoff decision making and implementation. On the other, the more decision-making factors considered the more complex the corresponding decision algorithm will be. As the result, how to design efficient and flexible decision-making methods need further research.This article focuses on the research of vertical handoff in the Heterogeneous/Convergence network in theory, technology and simulated aspects. Several type of vertical handoff decision algorithm and their defects are analyzed and summarized. The following works are carried out as the improvements:First, a cross-layer, flexible vertical handoff model is proposed as the improvement of MIH(Media Independent Handover) architecture, and the MIH protocol itself is developed to support the cross-layer context information collection and management, which is helpful in supporting fast handoff decisions and reducing the handoff implementation delay. Second, in order to solve the problem of the increasingly vertical handoff decision algorithm complexity caused by the growing number of factors, a novel handoff decision mechanism is presented, which improve the decision-making efficiency and provide new ideas in the research of vertical handoff in Heterogeneous/Convergence network.Third, the simulation verification is carried out which using UMTS coupled with WLAN as the underlying Heterogeneous/Convergence network. The result shows the effectiveness and correctness of the whole research. |
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