Research On Key Technologies Of Mobility Management In Heterogeneous Wireless Networks

The future wireless network is a heterogeneous network with seamless convergence,which bases on the full IP technologies,supports a large amount of wireless access technologies and roaming service.To achieve effective convergence of the heterogeneous networks and support mobile computing,ubiquitous computing, the key is the generalized mobility management technology that is open,efficient,and access technology independent.In this thesis,the technologies about the mobility location management,the handoff decision strategy between the heterogeneous networks,the handoff management system model with multi-protocol cooperation based on MIH(Media Independent Handover)and simulation platform for heterogeneous networks with multi-interface are studied.In this thesis,we introduce the important role of mobility prediction algorithm for heterogeneous wireless network,and propose the location prediction algorithm based on the dividing sensitive region in the cell.With the help of dividing sensitive region,the Markov predictor is optimized,which improves the prediction accuracy of the Markov predictor,and resolves the expansion problem of state-space in high exponent Markov models.We propose dividing logic cell idea by the homogeneous mappings,which can shield different characteristics of different wireless networks' cells.On the basis,the location update and paging are realized by mobility prediction algorithm in heterogeneous wireless networks.By comparing and analyzing traditional methods of multiple attribute decision making,TOPSIS(Technique for Order Perference by Similarity to Ideal Solution)is chosen,which is with a simple calculation and the relative superior performance.The concept of fuzzy logic control is introduced for the mathematical expression of multi-attribute decision in heterogeneous wireless networks.Then the TOPSIS vertical handoff algorithm based on fuzzy logic control is given.And the adaptive control technology is also introduced for the multi-attribute handoff decision,such that the decision strategy is more in line with the actual needs of users.With the development of the next generation network technology,SIP(Session Initiation Protocol)and FMIPv6 protocols will become the necessary ones in future heterogeneous wireless networks.But,the research on the joint multi-protocol handoff is rare in future heterogeneous wireless networks.In this thesis,to consider voice service for sensitive of the handoff delay,a handoff management system model with multi-protocol cooperation based on MIH is proposed;the theoretical research on the calculation of the pre-handoff time and the received signal strength prediction algorithm are achieved;and combining with the dynamic threshold settings,the fast handoff is realized with no occurrence of too late or too early handoff.Based on the NIST mobility package software,we develop the handoff management system with multi-protocol cooperation based on MIH and verify performance of fast handoff of the handoff management system in WiMAX-WiFi heterogeneous networks.