Leo Satellite Communication System Switching Strategy Research And Simulation Platform Design

Low earth orbit satellite communication systems could play an important role in future mobile communication networks due to their characteristics, such as global coverage and low propagation delay. During the design of satellite system, the study of handover management is one of the most important factors. The rotation of LEO satellites around the Earth results in a small visibility period of a satellite in a cell. As a result, a user terminal can be served by a number of spotbeams and satellites during the duration of a communication, resulting in handovers. In the process of the handover, in order to increase the resource utilization, the problem on how to fulfill the optimal allocation of the channels should be solved.In this dissertation, the handover schemes for LEO satellite communication systems are introduced and discussed in detail. On the basis of the integrated consideration on handover, channel allocation, the appropriate handover strategies are proposed to reduce the new call blocking probability and handover call dropping probability. Thus, the proposed strategies can improve the channel utilization efficiency and the system performance. The main contents are composed of the following.In Chapter 1, brief introduction of satellite communication system is given. And current development of handover management and routing technologies are described. Then the main work of this paper is introduced.In Chapter 2, an improved mini-hop strategy is proposed for LEO satellite constellation system from two existed strategies. This strategy makes fully use of the variation protocol of the LEO constellation network topology in order to solve the inter-satellite handover issue. Compared with mini-hop handover strategy, the simulation results show that the new strategy performs better with lower loads, lower handover call blocking probability and new call blocking probability.Handover technologies of spotbeam are mainly studied in Chapter 3. Then a time-based guaranteed handover strategy is proposed. Simulation results show that this scheme increases the resource utilization. In Chapter 4, a simulation platform for LEO satellite communication system is designed based on OPNET. And it is used for the research of handover management. The results got from it are reasonable and this system can give some supports for the simulation and realization of handover strategies.The dissertation is summarized in the Chapter 5. Finally, the future research work is pointed out.