The Research On Key Technologies Of Heterogeneous Mobile Networks

As a result of rapid progress in research and development, today's wireless mobile networks exhibit several heterogeneous communication networks. Next generation wireless networks are expected to compose various heterogeneous wireless access networks. The heterogeneity of networks and the diversity of mobile terminals can greatly extend the physical connectivity and traffic of wireless networks. The capacity of wireless mobile system is increased by integrating various heterogeneous networks.The integration of heterogeneous networks is the trends of development of mobile communication systems. On of the most important characteristics of NGN is the diversity of access. Namely, the communication environment is heterogeneous and the access is asymmetrical. The differences in implementation technique, transmission mechanism, and architecture and control scheme among each network are remarkable. Hence, the integrated wireless system brings new challenge in many key techniques such as mobility management, joint resource management and network security. Because of the difference of heterogeneous networks architecture and the diversity of requirements of mobility management, every kind of access network adopts different mobility management technology. It causes the result that subscribers can roam in homogeneous networks but cannot move across heterogeneous networks. The NGN wants to converge the heterogeneous networks to support mobile computing and ubiquitous computing and ubiquitous computing, and the open and efficient generalized mobility management is one of the key technologies.On the other hand, except of the inherent security requirement in each network, the heterogeneous networks will meet some new secure problems, such as inter-network security and the problems come from the diversity of new traffic. With the extension of network applications and the diversity of access technology, the attackers are more and more serious. So the security plays a crucial role in various key technology of heterogeneous networks.The dissertation mainly makes scientific researches on mobility management and network security in heterogeneous networks.Firstly, the mobile SIP (Session Initial Protocol) is investigated. Although SIP is an important application-level mobility management protocol used for supporting seamless mobility, the handoff mechanism in the traditional SIP mobility architecture suffers from undesirable delay and packet loss, which is unacceptable to delay-sensitive real time applications. In this dissertation, an improved SIP mobility architecture based on Mobile Anchor Point (MAP) that supports fast soft handoff is proposed to alleviate the transmission delay of the SIP mobility signaling messages and reduce the packet loss. Moreover, the Anchor Mobility solution provides a set of whole location management and handoff management schemes for multi-mode mobile terminals through the modeling of the anchor field mobility management in the heterogeneous environment.Then, the security problems existing in the Anchor Mobility model based SIP terminal mobility architecture is deeply analyzed in this thesis. A secure scheme named SEMAP is proposed to solve the secure routing problems with the anchor agent server. The SEMAP can improve the limitation of traditional secure routing protocol in packet transmission delay and route reconstruction.