卫星可靠组播中的差错控制技术研究

发布时间：2018-02-28 08:29

本文关键词： 卫星组播网络差错控制分组级FEC技术　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：卫星通信在全球通信中扮演着重要的角色,除了具有全球覆盖的特点以外,它们能够还支持宽带业务和灵活的网络配置。与地面通信网络相比,卫星通信网络因为本身具有天然的广播特性、覆盖区域广、用户入网快速灵活等特点,在支持组播方面有着得天独厚的优势。目前,随着业务的拓展和卫星处理能力的加强,通过卫星支持组播已逐渐开始成为未来网络通信的发展方向之一。然而,与地面网络相比,通过卫星进行可靠组播也面临着一些问题。一是时延问题:对于卫星通信而言,链路传输的长时延会使组群管理的IGMP协议、以及组播路由协议的使用大打折扣。二是较高的分组出错概率:卫星网络中暴露于太空之中的无线信道存在着大量的不稳定因素(天气状况的复杂多变,多径干扰等),这导致了较高的误比特率,从而也产生了相对地面较高的分组出错概率。因此,如何克服信道大时延的影响,如何提高恶劣气候条件下的卫星组播传输性能,尤其是如何消除雨衰影响是组播技术能否在卫星通信中成功应用的关键因素之一。本文正是基于可靠性的考虑,对于卫星组播中差错控制技术的应用与实现进行了研究,主要研究内容如下:介绍了卫星组播通信中分组错误率的概念以及分组错误率对于卫星组播的影响,并介绍了三种卫星组播中常用的差错控制技术,包括物理层FEC技术、ARQ技术以及分组级FEC技术。对卫星组播通信中的相关技术的进行了具体的分析和介绍。给出了两种常用的分组级FEC的介绍—采用RSE码的分组级FEC技术和采用卷积码的分组级FEC技术,包括其实现方法和优缺点等等。此外,还介绍了结合ARQ的分组级FEC(HEC)的概念。基于MATLAB仿真设计了采用RSE码的分组级FEC技术,对其进行了深入分析。以带宽占用率和时延为量度,通过大量的MATLAB仿真,分析讨论了接收机群组大小、FEC参数、包大小以及降雨等的影响,并对这两种网络模型的性能进行了比较。而后在此基础上对有反馈信道的卫星组播网络模型提出了改进方案并对仿真结果进行分析,得出了大量的结论。众多的结论对实际组播系统的应用具有较好的指导意义。
[Abstract]:Satellite communications play an important role in global communications. In addition to their global coverage, they can also support broadband services and flexible network configurations. The satellite communication network has a unique advantage in supporting multicast because of its natural broadcast characteristics, wide coverage, rapid and flexible access to the network, etc. At present, with the expansion of service and the enhancement of satellite processing capacity, satellite communication network has a unique advantage in supporting multicast. Multicast supported by satellite has gradually become one of the development directions of network communication in the future. However, compared with terrestrial network, reliable multicast via satellite also faces some problems. The long delay in link transmission results in a cluster managed IGMP protocol, And the use of multicast routing protocols is greatly reduced. The second is the high packet error probability: there are a lot of unstable factors in wireless channels exposed to space in satellite networks. Multipath interference leads to higher bit error rate and higher packet error probability than ground level. Therefore, how to overcome the influence of large channel delay and how to improve the performance of satellite multicast transmission in bad weather, Especially, how to eliminate the influence of rain decline is one of the key factors for the successful application of multicast technology in satellite communication. Based on the consideration of reliability, this paper studies the application and implementation of error control technology in satellite multicast. The main contents are as follows: the concept of packet error rate in satellite multicast communication and the effect of packet error rate on satellite multicast are introduced, and three commonly used error control techniques in satellite multicast are introduced. It includes physical layer FEC technology and packet-level FEC technology. The related technologies in satellite multicast communication are analyzed and introduced in detail. Two kinds of commonly used packet-level FEC are introduced, that is, using RSE code. FEC technology and block level FEC technology using convolutional codes, In addition, the concept of packet level FEC combined with ARQ is introduced. Based on the MATLAB simulation, the block level FEC technology using RSE code is designed and analyzed in depth. The bandwidth occupancy and delay are taken as measures. Through a large number of MATLAB simulations, the effects of receiver group size, packet size and rainfall are analyzed and discussed. The performance of the two network models is compared, and then the improved scheme of satellite multicast network model with feedback channel is proposed and the simulation results are analyzed. A large number of conclusions have been drawn, and many conclusions have good guiding significance for the application of practical multicast systems.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN927.2

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