| With the development of society and the progress of science and technology, the demands of personal communication become stronger and stronger. The Mobile IP which is used as a supporting technique of mobility for Internet has the ability to use various network technical to fulfill the assignment which make whoever communicate with whoever else at whenever and wherever to exchange whatever information. So, the Mobile IP technique becomes a focus of the two international standardization organizations, i.e., IETF and ITUT. The main achievements and innovations of this dissertation are as follows:(1)In this paper, the Mobile IP protocol of the Mobile IP task group has been deeply studied. When the protocol is applied in the situation of micro mobility, it has many difficulties such as the increase of network flow, the enhancement of handoff delay and enlargement of agent load et al. So, various special supplemental protocols for micro mobility (i.e., the micro mobility protocol) have been reported in the previous works. In these protocols, the Mobile IP is regarded as acquiescence protocol in case of the macro mobility (i.e., the macro mobility protocols) and their combination can improve the deficiency of the Mobile IP.An applied model of the Mobile IP has been presented based on the thorough study about the macro mobility protocols and various micro mobility protocols in this paper. In addition, based on above model, we theoretically deduce and calculate the macro mobility protocol and various micro mobility protocols, and analysis the ability of their registered cost and the packet loss probability caused by handoff.The results show that utilizing both micro protocol and macro protocol not only macro protocol may get very high performance of network. (2) Since the achievement of the Mobile IP depend on the mobile communication network, these studies about the mobile communication network to supply more reasonable manage strategy of the Mobile IP are theoretical and practical significance. In this paper, the multi-tier cell structure which gradually become the main mobile communication structure is deeply studied and mobility manage scheme based on the multi-tier cell structure is gained. In this scheme, foreign agents are separately as mFA, uFA and pFA on corresponding layers according to the types of cells that is managedby them. When the handoff of MN occurs, MN can register on corresponding FA.There are two schemes for MN register: single care of address (i.e., sCOA) and two care of address (i.e., tCOA) and they have respective characteristics. In order to reduce the message loss, it is reasonable to establish a temporary tunnel between the new FA and old FA. If any message sent to MN arrives at the old FA, the old FA will send it to the new FA, and then the new FA will re-send it to MN.In addition, according to choosing mobile model, the simulate calculation for the different MNs in different types of cells is made and the corresponding handoff frequency is obtained. According to the above results, we calculate and analysis the performance of sCOA and tCOA.From the analysis by synthesis, we can find adopting the mobility management of Mobile IP based on multi-tier is prerequisite and very efficacious. This mobility management will fulfill vary demands of communication and get more scalability(3) Any characteristic of the lower layer chain was not considered in original design of the Mobile IP, but the demand to real-time becomes higher with the increase of the Mobile IP application. So, it is necessary to deeply study the delay increase caused by handoff in order to reduce its effects. Now a conceive that the L2 trigger is used to previous trigger layer 3 handoff has been reported, and it is also deeply studied in this paper. These studies are as follows:Firstly, based on the deep study on the handoff process, the handoff ways and the handoff criteria in the mobile communication, a new concept about L2-trigger is given in this paper. Comparing with previous schemes (5 trigger...
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