Leo Satellite Communication System Core Network Performance Simulation

The commercial networks of 3rd Generation (3G) mobile communication systems are built around the world. Satellite communication system is an important part of the 3G mobile communication systems and the future global personal communication systems. LEO satellite communication system has merits of worldwide coverage, low-transmission-delay, low-power and strong-anti-disaster. So it is one of the hot research spots. LEO satellite communication system consists of space part, ground part and user part. The user part is composed of fixed and mobile user equipments. The space part is composed of LEO satellite constellation. Considering the complexity and expensive cost of the satellites, the control and mobility management of the system are set at the ground part, so the core network is the main topic of this dissertation.In this dissertation, according to the core network of LEO satellite communication system, we design and simulate a LEO satellite communication system based on OPNET, and study the recovery-ability and location management strategy of the system. This paper includes five parts. The first chapter introduces the knowledge learned by the author during the postgraduate period, the 2nd, 3rd and 4th chapter are the main chapters, and give the detailed description of research work accomplished by the author in postgraduate period.The first chapter introduces the development of mobile communication, generalizes satellite communication system and LEO satellite communication system, describes the location management strategy of LEO satellite communication system,the recovery ability of database and the system simulation software OPNET. At last, the author introduces the research significance and the arrangement of the dissertation.In chapter 2, considering integrated performance of the recovery-ability and location management, I propose a location management strategy of setting multi-HLR (Home Location Register) which reduces location management cost and improves the performance of the system.The recovery-ability of LEO satellite communication system is studied in Chapter 3, the backup of HLR database, the setting of gateway-station and the topology of core network of LEO satellite communication system are considered to improve the stability of the system.Chapter 4 builds an integrated simulation system platform of LEO satellite communication system by OPNET simulation software. The node and module design of the gateway station, the central database and the link are described in detail. According to the analysis of the call flow, we simulate the process of the call by the simulation system, and make a statistics of the delay of setting-up a call.The last chapter gives summarization of the dissertation, and describes the progress of the research and the future research work.