| In recent years, the wireless communication and Internet have become the most rapidly developing technologies, and the network size and the number of users explode at the same time. Satellite communication, as one of the significant modern communication technologies, has made a great deal of progress during the past 30 years. Due to the increasing demands for multimedia services supporting high bit rates and mobility, it is necessary to integrate ATM, TCP/IP and satellite technology to construct the satellite component of the global mobile Internet. In this scenario, distinctions between terrestrial networks and satellite networks, as well as between fixed networks and 3G mobile networks, will cease to coexist in the universal mobile telecommunication system (UMTS). Pervasive and ubiquitous exchange of information is the primary purpose of creating an integrated UMTS, in which mobile nodes (MN) can freely move around and still access public or private databases and communicate with any others in an efficient and cost-effective way. Mobility, QoS and global seamless coverage have become the most important characteristics of UMTS. Satellite networks have the inherent advantages of wide area coverage, unique broadcast capability and no regional restrict, so they will play a significant role. Whereas, for their inherent disadvantages, the traditional GEO satellite communication systems will be incompetent for some real-time services, so the NGSO satellite mobile communication systems with broadband and QoS guarantee have become the research focus. According to the key techniques and development trends of the NGSO mobile satellite communication, this dissertation mainly focuses on the networking technologies in the NGSO satellite networks, which includes constellation design, inter-satellite link, spot-beam design, routing and handover.Chapter 1 is the preface, which concisely introduces the development, status and perspective of the satellite communication, and the arrangement of this dissertation. Chapter 2 mainly studies constellation design. Firstly, this chapter gives a brief introduction of the development of constellation design and two classical methods to design global constellation. Secondly, this chapter proposes a novel method to design satellite constellations for partial coverage, and discusses the steps of designing and optimizing a constellation in detail, too. Thirdly, this chapter proposes a new method to realize global satellite communication, which is based on the regional constellation. Since the methods proposed in this chapter are quite suitable for the situation of our country, they have both novelty and great value in practice. At last, this chapter discusses the method and steps to put the diversified satellite constellations in practice.Chapter 3 studies inter-satellite link (ISL) and multi-beam antenna. They are the significant components of the satellite communication system and affect the system performance in many ways, including investment, networking, capability, services and so on. In order to be convenient for engineering application, this chapter addresses the mathematic formula for ISL and discusses the laws that ISL's characteristics vary with the satellite constellation parameters and time. Discussed the relationship between the link loss and the spot-beam antenna gain, the link level balance spot-beam model is proposed to keep the balance of the link level budget margin of the different spot beam cellars. As the results show, this model can make a better use of onboard power than other models and have practical values.Chapter 4 studies the LEO satellite data communication system. The system without ISL mainly provides pure data service, and consists of the LEO satellites and the ground gateway stations that connect with each other by the high-speed terrestrial network. Other than that of ORBCOMM and Globalstar, its gateways must be restricted in our country. This chapter proposes the shortest delay routing algorithm that can work out the shortest time delay and find ou...
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