【作者】 喻香；

【导师】 汪小燕； 董燕；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2008， 硕士

【摘要】 切换技术作为移动卫星通信网络的一项关键技术,实现在通信进行过程中允许用户终端移动、在恶劣的无线传输条件下恢复并保持通信、平衡网络的业务负荷等功能。用户终端的移动性对切换性能有重要影响,本文重点对地面静止终端和高动态终端在移动卫星通信网络中的切换技术进行了研究。首先,基于STK软件进行建模,仿真分析了用户终端在低轨卫星通信网络和同步轨道卫星通信网络中的可视性。终端类型包括地面静止终端以及航天器、低空高速飞行器、LEO卫星等高动态终端。其次,针对地面静止终端在低轨卫星网络中的切换的场景,在综合考虑接收信号的信噪比和卫星负荷这两个因素的基础上,分别提出了负荷和信噪比加权策略、改进的最小负荷策略。再次,对高动态终端在同构卫星网络中的切换技术进行了研究。设计了核心信令保护机制的精简切换信令流程,定义了三种切换定时器。最后,对高动态终端在异构网络中的切换技术进行了研究。以一种统一的方式设计了从临近空间平台切换到卫星网络的媒介独立切换协议栈参考模型,给出了高动态终端发起的切换信令流程。通过OPNET仿真验证,负荷和信噪比加权策略的阻塞率低于改进的最小负荷策略,后者的掉话率最低,但切换请求到达率较高,网络的信令负荷较大;核心信令保护机制的切换信令流程可以优化高误码、长时延的通信传输环境下的切换性能。更多还原

【Abstract】 A key technology of the mobile satellite communication networks is handover, which implements functions such as allowing user terminal move during the communication process, recovering and holding communication in the bad wireless transmission condition, avoiding interrupt between user terminal and the network, balancing traffic load in the network, etc. For the mobility of the user terminal has an important affect on handover performance, the thesis mainly researches on handover technology about stationary terminal on the earth and high dynamic terminal in the mobile satellite communication networks.Firstly, the visibility of user terminals in the low earth orbit and geosynchronous orbit satellite communication networks has been analyzed. There are different kinds of terminals, that is, stationary terminal on the earth, and three kinds of high dynamic terminals which are space aerocraft, low altitude aerocraft, low earth orbit satellite.Secondly, integrating the SNR of the received signal with the load of the satellite, load & SNR plus scheme and improved minimum load scheme have been proposed for the handover scene about the stationary terminal on the earth in the low earth orbit satellite network.Thirdly, the handover technology about high dynamic terminal in the satellite network has been researched, a key signaling protected and condense handover signaling procedure has been designed and three kinds of handover timers have been defined. Finally, the handover technology about high dynamic terminal in the heterogeneous network has been researched; a media independent handover protocol stack from near space platform station to satellite network has been designed in a uniform way. Besides, high dynamic terminal motivated handover procedure in the heterogeneous network from near space platform station to GEO satellite has been given.OPNET simulation results prove that the two proposed handover schemes can optimize the handover performance for the handover scene about the stationary terminal on the earth in the low earth orbit satellite network; the key signaling protected handover procedure designed can optimize the handover performance in high bit error rate and long delay space transmission environment.更多还原