Research On Mobility Management In IP/LEO Satellite Network

In recent years, communication network as the information infrastructure hasundergone tremendous and profound changes with the rapid development of worldwidenetwork and information technology. Since the ground communication network cannotdemand the increasing demand for multimedia communication, satellites are used toaccess the Internet, which is main direction of the development of satellitecommunication and also is an important part of the air-space-ground integrated network.Guaranteeing the network global coverage by IP/LEO satellite is a solid foundation forproviding better personal communication services in future mobile communication.IP/LEO satellite network is capable of supporting users’ mobility services and providingwider region for users. But the special network architecture, the satellites’ limited datastorage capacity and data processing ability, and the longer transmission delay all havebrought severe challenge for mobility management in IP/LEO satellite network.Mobile IP protocol is the basic mobility management protocol which can achieve themobility need in IP network. But Mobile IP protocol also has some obvious deficiencies.Aimed at those deficiencies, there have been many improved algorithms such as thehierarchical concept, the prediction algorithm, supporting fast handover, adding pagingmechanism and so on. But while using in satellite network, these optimizationalgorithms of MIP need to face the mismatching of the network structure, the decline ofoptimization performance and some other problems. Therefore, analyzing the problemof mobility management and designing the suitable mobility management algorithm isan important research topic in IP/LEO satellite network.On the basis of analyzing ahd absorbing the latest research results both here andabroad, this paper focuses on the three aspects of mobility management which are thelocation management, handover and the network mobility technology in IP/LEOsatellite network, and several new conclusins are obtained. The main research works areas follows.First, after analyzing the different mobility of the mobile users in IP/LEO satellitenetwork, this paper persents a dual-location area location management method based onlocation information. By using both the satellite and ground location areas, the locationupdate frenquency of high-speed users and flip-flop users is declined on the basis ofkeeping the low location update frenquency of low-speed users in the network. Pagingscheme is added to decrease the location upadate messages in the network. At the sametime, by adding MN’s location information in the location update messages, the networkis able to paging the users within the area the users latest updated, and the successsprobability of first paging is increased. Through the theoretical analysis and simulation, the preformance of location information based dull-location area location managementtheod is proved to be lower in location management and paging cost compared withother strategies. The relationship between the ground sation coverage area and theperformance of the strategy is further discussed.Second, aiming at the problem of increasing handover time dely caused by the longtransimission delay in satellite network, a SIGMA handover prioritization scheme basedon location information is proposed in this paper. The characteristic of multi-homing oftransport layer protocol mSCTP is used in this method. Two IP adresses can be added inone SCTP association by the users. After access to the new router, the users can use theirnew IP adress first instead of registering the new IP adress at the home agent first. Andthe handover delay can be decreased. The prediction algorithm of users’ handover timebased on location information in IP/LEO satellite network is also proposed. In theprediction algorithm, the satellites’ ephemeris information and the users’ locationinformation are both used. The SCTP association set up signalling is saved and the usersalso can set the new IP adress as the primary adress during the handover time. Thesimulation proverd that the proposed scheme performance better in handover delay andpassage loss rate campared to the traditional SIGMA scheme.Third, a design idea of NEMO based satellite network structure based on thecharacteristic of network mobility of IP/LEO satellite. The satellite network whis act asthe subnet of the ground Internet network is connected to the ground network throughone or more satellite access routers. The routing processes of the satellite act as both thecorresponding node and the access router based on NEMO basic support protocol areanalysed. Two types of routings which make sure the network mobility users canconnect to the ground Internet network through satellite network are also analysed.Analysis shows that the network structure can reduce the dependence of the satellitenetwork on the ground network, the communication connectivity is also betterguaranteed. Simulation results show that applicating NEMO basic support protocal insuch network structure can get better performances in signalling cost and packet lossrate.