中文摘要：

主要研究在同步轨道卫星中的多用户接入控制方案，分析了现有时分多址接入（time division multiple access，TDMA）的优缺点，在基于TDMA的情况下给出了改进的自由接入／优先级按需分配接入方式（freeaccess／priority demand multiple access，FA／PDMA），保证多用户接入时的公平性，以及在业务量不断增大的过程中，如何在大传播距离下通过优化现有的多址接入算法来确保用户的接入时延和端到端时延；并提出了用户在高速移动过程中卫星之间的切换策略算法。最后用OPNET仿真软件搭建网络平台，和TDMA进行对比仿真分析，得出结论，实现在大时延情况下，用户的实时接入和不同卫星之间的有效切换。

英文摘要：

This thesis focuses on the scheme of multiple clients accessing in geosynchronous satellite, analyzes the advantage and disadvantage of time division multiple access （TDMA）, comes up with an improving ac cess algorithm named free access/priority demand multiple access （FA/PDMA）based on TDMA to ensure the fairness when multiple clients accessing internet is demanded. The existing multiple access algorithm is opti mized to guarantee the clients＇ accessing delay and end-to-end delay when traffic packets increasing. In addi tion, a handoff algorithm between satellites when clients moving quickly is proposed. Finally the proposed algorithm is compared with the TDMA algorithm by using OPNET to construct internet platforms. Simulation resuits demonstrate the priority of FA/PDMA, draw the conclusion of the instantaneity access and effectively handoff in the case of big time delay.