Research On Mobility Management Of Mobile IP

With the development of society and the advancement of science and technology, the demands of personal communication become increasingly urgent. Mobile IP which is used as a supporting technique for the mobility of Internet has the ability to use various network technical to fulfill the object which make whoever communicate with whoever else at whenever, and wherever to exchange whatever information. At present, the Mobile IP technique has become a research focus of the two international standardization organizations, i.e. IETF and ITU-T, and has a wide application perspective.As a mobility management program, Mobile IP has many questions to be solved:Firstly, one of the important characteristics of next-generation wireless/mobile networks is to support different wireless access technology, thus it is critical that a general access infrastructure must be offered by next next-generation wireless/mobile networks so as to support interworking/interoprating between different wireless networks. IP technology is considered to be one of the best choices to realize this goal. So the mobility management program of the next next-generation wireless/mobile networks which is combined with mobile IP deserves to be researched deeply.Secondly, centralized mobility management program holds the advantage of simple implementation and easy maintenance, but the disadvantage of this program shouldn't be neglected, i.e. the disable of domain mobility management entity will result in serious consequence of communication interruption of the whole domain charged by that entity. The distributed mobility management program can overcome the drawback of centralized mobility management stated above and improve network robustness through several management entities at different locations of the domain which take the duty of distributed mobility management. Although the distributed mobility management is very flexible, it will add the system realization complexity and lead to extra costs for communication between different management entities. The distributed mobility management, as well as dynamic mobility management program which adaptively adjust the configuration according to the rules of time-varying mobility and call characters of different mobile hosts, act as the evoluation directions of future mobility management program in wireless/mobile networks.Thirdly, as a chief wireless access technology for current wireless/mobile network, Wireless LAN can offer high data rate and has been widely deployed in hot spot areas for public Internet access. At the same time, IPv6 is the trend for the futureInternet. So how to achieve the IPv6 mobility supporting in Wireless LAN needs to be further researched.According to the questions stated above, this paper puts emphasis upon several aspects as bellows and gets some corresponding conlusions.(1) A mobility management model based on mobile IP for next-generation all-IP-based wireless systems is proposed in this paper.With the development of wireless access technology, it has become increasingly urgent that mobile hosts roam across heterogeneous wireless networks. The mobility management program on network layer, due to its advantage of independence of low layers, i.e. data link layer and physical layer, can be applied to different wire and wireless networks. To the requirements, this paper proposes a mobility management model based on mobile IP for next-generation all-IP-based wireless systems, which can realize and support the seamless roaming and handoff of mobile terminals across heterogeneous wireless networks.(2) A novel distributed location management program for Mobile IP Regional Registration is proposed in this paper. This program, which is based on utilizing the advantages of logically hierarchical structure of the regional network, puts forward that under the precondition of traffic load below the definite traffic threshold, Foreign Agents at different levels can be chosen to act as Gateway Foreign Agent for mobile node. After researching on a regional network model and analyzing signaling cost, numerical results of signaling cost are calculated provided that this program is applied to Mobile IP Regional Registration. At the end of this chapter concerned, it comes to a conclusion that this program can reduce signaling cost by at least 10% and by means of distributing the effective traffic to several Gateway Foreign Agents, possible serious consequences of communication interruption resulted from the failure of one Gateway Foreign Agents will be avoided, thus the network robustness will be improved.(3) To solve the problem of handoff latency in the procedure of IEEE 802.11 mobile hosts'handoff, this paper presents effective measures to reduce handoff latency of layer-2 and layer-3 after analyzing the handoff procedure of MH in WLAN. Combined with the advantages of low-latency handoff mechanism in Mobile IPv4 and mobile agent buffer technology, a smooth handoff mechanism with Bi-directional Edge Tunnel (SHMTW) is put forward. The simulation result indicates that SHMTW not only reduces the possibility of packet loss in the process of handoff, but also averagely lowers handoff latency above 500ms and evidently increases the Goodput of TCP approximately by 70%. Therefore better effect of seamless handoff is achieved.(4) In the last chapter, the author researches the performance of three programs:Mobile IPv6, Hierarchical Mobile IPv6 and Fast Handovers for Mobile IPv6 on the basis of wireless LAN, and then indicates that two protocols, which are HMIPv6 and FMIPv6, compared with MIPv6, have made some improvement in performance. At last, the author comes to a conclusion about the perspective of the development and improvement of IPv6 mobility protocols in WLAN.