卫星通信网络基于信道特性的资源管理及路由技术研究

【作者】 朱析；

【导师】 朱立东；

【作者基本信息】 电子科技大学 ， 通信与信息系统， 2008， 硕士

【摘要】 卫星移动通信是指利用卫星转发器作中继而实现移动终端之间的无线通信,是未来个人通信系统的重要组成部分。和地面无线通信系统相比,卫星信道有其特殊性。论文结合卫星信道的特点,研究信道分配、路由、切换等技术。第一章是绪论,简要介绍了卫星移动通信的发展状况,接着对卫星网络常用的信道模型、信道分配策略、切换策略、路由策略作了综述,并说明本文的研究内容及结构安排。第二章研究信道传输特性对卫星网络切换的影响。在卫星与地面终端之间的星地链路中,存在复杂多变的信道环境,这些因素对系统的切换性能有着重要影响。首先建立星地链路信道模型,并将此模型应用于切换过程,通过仿真得到信道特性对于切换性能的具体影响。第三章研究信道传输特性对资源分配的影响。结合信道传输特性,将功率截断门限应用到信道分配中去。以往的文献在研究信道分配策略时,都是单纯的从如何进行信道分配这个角度去思考。但是在实际系统中,在某些极端情况下信道资源虽然进行了分配,但并不能满足基本的通话条件,造成了信道资源的浪费。因此,本章根据卫星信道的时变性将功率截断门限这个概念运用到信道分配过程中去,系统根据用户发射功率判断信道环境已经恶化到无法满足通信要求时,强制性中断此次通信,将信道资源分配给其他用户。第四章提出了带有优先级的最短时延卫星路由策略,将业务分为话音业务和数据业务,根据业务时延要求的不同,优先处理话音业务,再根据源卫星、目的卫星的位置,确定路径延时的度量标准,以此得到经过优劣排序的候选路径集合,并对最佳路径进行计算。仿真结果表明,算法显著降低了话音业务的时延水平,有效提高了通话质量。第五章对全文进行了总结。更多还原

【Abstract】 The satellite mobile communication can realize the radio communication between the mobile terminals by using the satellite repeaters which act as relay. Among the satellite mobile communication systems, the LEO-MSS’s (Low Earth Orbit Mobile Satellite Systems) possesses the wide development space due to their global seamless coverage, much shorter transmission delay, less power requirement for the user terminals and strong ability in anti-ruin. Moreover, they will play an important role in the future’s Personal Communication Systems (PCS).Chapter 1 is the preface, which concisely introduces the development status of the satellite communication, then summarizes the common channel model of satellite network, channel assignment algorithm, handoff algorithm and routing algorithm, at last explains the research content and the arrangement of this dissertation.Chapter 2 studies the influence of satellite network handoff by channel transmission characteristic. There are complex and time-varying channel conditions between LEO satellite and terrestrial users, and these factors would have important impact on handover performance. This paper constructs satellite-earth channel model firstly and applies the model in the process of handoff. At last, the influence of channel model on handoff performance is got by simulation.Chapter 3 mainly studies the influence of resource assignment by channel transmission characteristic. With channel transmission characteristic apply power truncation threshold to channel assignment. In study of channel assignment, those literatures just study how to assign the channel. However in actual system, the channel resource have been assigned in some extreme situation, but that can not be satisfied with based communication condition, make the channel resource can’t be used efficiently and recede the system performance. So power truncation threshold is used for channel assignment. The system judges whether the channel condition meets communication requirements based on the user’s emission power, if not, the system intermits this operation constrainedly, and assigns channel resource to other operation. Chapter 4 proposes a least time-delay routing algorithm with priority, voice and data service are both taken into account, and voice service is preferential. Then measure metric of path delay to carry out calculation for best path based on positions of source and objective satellite, and get a candidate path collection by good and inferior sorting. The simulation results indicate that the algorithm can reduce the time-delay of voice service obviously, and improve the call quality effectively.The dissertation is summarized in the chapter 5.更多还原