移动多媒体广播无线网络覆盖及设计实例

发布时间：2018-11-06 16:42

【摘要】：随着手机通信的不断发展,一个新的“手机电视”概念随之产生。国外的ISDB-T、DVB-H、MediaFLO、DMB手机电视标准逐渐成熟并投入商业运营。作为我国自主研发,具有完全知识产权的移动多媒体广播(CMMB, China Mobile Multimedia Broadcast)标准也正式成立,并投入到建设运营中。移动多媒体广播以UHF频段的信号覆盖地面,作为一种新兴的无线广播技术,如何进行信号覆盖,如何解决覆盖中所遇到的一些问题,是本文重点研究的对象。文章中介绍了电磁波的分类、信道环境分类、信号损耗分类。电磁波的分类是根据电磁波经过不同路径到达终点所区分的。传播信道的分类则是根据不同的地理环境,经过概率学计算得出的数学模型。信号损耗分类体现了电磁波在不同情况下的功率损耗的特性。论文中还着重介绍了OFDM、保护间隔、信道编码、同步技术,这些技术是CMMB的关键组成部分。以上知识为CMMB的无线覆盖提供了理论依据。作为本文的研究对象,CMMB的无线覆盖是重点探讨的问题。首先,介绍了CMMB的网络架构,解释了信号由卫星传输至地面,再由发射机发射至移动终端上的过程。根据技术标准和工程实践经验,归纳总结了CMMB的三种覆盖方式,分别是单发射台站、单频网、信号补盲。文中针对这三种覆盖方式,从概念、适用范围、原理等多方面进行分析。单频网作为一种CMMB无线覆盖的重要的方式,文中提出了同频干扰、保护间隔等概念,通过OFDM中信道编码的特性,计算出两个发射机台站之间的间隔不得超过15.36公里,否则两个发射机台站之间的区域必定会产生同频干扰。其次,通过对本人主持和参与的两项CMMB工程,对上述无线覆盖相关理论和设计方法进行应用和验证。通过南昌市单频网的网络仿真计算来判断规划是否可行,根据仿真结果发现存在有效覆盖范围减少、同频干扰、时间不同步、频率不同步等问题,根据理论知识和实践经验针对这些问题分别提出了解决办法。上海市虹桥枢纽西航站楼室内分布系统包含了CMMB和GSM、CDMA、WLAN、WCDMA等多种通信信号的覆盖,从这个设计实例中可以归纳CMMB与其他系统之间的合路设计思路及方式,为将来CMMB更多的与其他信号合路共建室内分布系统提供了参考。最后,总结了论文的结构和研究对象,并提出了CMMB无线覆盖中需要进一步研究的方向和思路。
[Abstract]:With the development of mobile phone communication, a new concept of mobile TV has come into being. ISDB-T,DVB-H,MediaFLO,DMB mobile TV standards abroad gradually mature and put into commercial operation. As an independent R & D, mobile multimedia broadcasting (CMMB, China Mobile Multimedia Broadcast) standard with full intellectual property rights has been established and put into construction and operation. Mobile multimedia broadcasting covers the ground with the signal of UHF band. As a new wireless broadcast technology, how to cover the signal and how to solve some problems encountered in the coverage are the main research objects of this paper. In this paper, the classification of electromagnetic wave, channel environment and signal loss are introduced. The classification of electromagnetic waves is based on the electromagnetic waves passing through different paths to the end point. The classification of propagation channel is a mathematical model based on different geographical environment and probabilistic calculation. Signal loss classification reflects the characteristics of electromagnetic wave power loss under different conditions. In this paper, OFDM, protection interval, channel coding and synchronization techniques are also introduced, which are the key components of CMMB. The above knowledge provides a theoretical basis for wireless coverage of CMMB. As the object of this paper, the wireless coverage of CMMB is an important issue. Firstly, the network architecture of CMMB is introduced, and the process of signal transmission from satellite to ground and then from transmitter to mobile terminal is explained. According to the technical standard and engineering practice, three coverage modes of CMMB are summarized, which are single transmitter station, single frequency network and signal blind compensation. In this paper, the concept, scope of application, principle and other aspects of the three coverage methods are analyzed. As an important way of CMMB wireless coverage, the concepts of co-frequency interference and protection interval are put forward in this paper. Through the characteristic of channel coding in OFDM, the distance between two transmitter stations is calculated not to exceed 15.36km. Otherwise, the area between the two transmitter stations must produce the same frequency interference. Secondly, the above theories and design methods of wireless coverage are applied and verified through the two CMMB projects which I host and participate in. The network simulation calculation of Nanchang single frequency network is used to determine whether the plan is feasible or not. According to the simulation results, it is found that the effective coverage range is reduced, the same frequency interference, the time is out of sync, the frequency is not synchronized and so on. According to theoretical knowledge and practical experience, respectively, solutions to these problems are put forward. The indoor distribution system of the west terminal of Hongqiao Hub in Shanghai contains the coverage of many kinds of communication signals such as CMMB and GSM,CDMA,WLAN,WCDMA. From this design example, we can conclude the design ideas and methods of the road combination between CMMB and other systems. It provides a reference for CMMB to build indoor distribution system together with other signalling roads in the future. Finally, the structure and research object of the thesis are summarized, and the directions and ideas for further research in CMMB wireless coverage are put forward.
【学位授予单位】：东华大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN943

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