【作者】 陈磊；

【导师】 覃剑；

【作者基本信息】 重庆大学 ， 信息与通信工程， 2018， 硕士

【摘要】 频繁发生的自然灾害会给人类的生命财产造成巨大的损失,如2008年中国四川地震,2010年海地地震。此外,生活中还有很多突发事故,如火灾,交通事故等。灾难一旦发生,基础网络设施往往遭到破坏,使得复杂的救援环境中缺乏完善的网络基础设施和应急通信设备,导致很多信息传递失败,错过了最佳救援时机,使得国家人力财力遭受不必要的损失。因此,完善的应急通信系统显得尤为重要。应急通信过程中,大量的现场情况需要进行实时传送,视频信息因其具有信息量大、直观的特点越来越受到关注。通过实时地回传视频数据,指挥中心可以方便地进行远程监控、指挥和调度。本文借鉴地面数字电视广播标准DVB-T2,设计了一套应急视频通信系统的物理层方案。本系统具有传输远、广覆盖、高带宽、低时延等特点。与目前的公网通信相比,基站数量少,结构相对简单,采用点对点的传输方式,且不需要依赖固定的网络设备,能够满足应急视频通信的需求。具体工作包括:首先,本文对系统中的关键技术进行分析并建模,具体包括:系统帧结构的设计、OFDM技术、LDPC编解码技术、系统同步技术。LDPC译码算法、系统同步算法是本次设计的难点,关键部分的算法通过MATLAB仿真实现,来降低算法实现的复杂度,设计并实现硬件算法。其次,整个系统在Simulink上进行仿真,验证不同信噪比下的传输性能。最后,完成整体方案的硬件实现。硬件平台以Xilinx公司的XC7Z020-CLG484芯片为核心,采用Verilog语言完成物理层部分的设计,包括时钟产生模块、Ts码流同步模块、发射端速率转换模块、加扰模块、BCH编码模块、LDPC编码模块、符号交织模块、星座映射模块、导频插入模块、OFDM子载波映射模块、IFFT变换模块、T2帧组帧模块等发射端部分及接收端对应的解调部分。对系统的发射端、接收端及其整体进行测试,实现了整个系统的开发和验证,能够满足系统设计的要求。更多还原

【Abstract】 There have been many natural disasters that occur frequently,such as the Sichuan earthquake in China in 2008,the Haiti earthquake in 2010,which could cause major personnel and property losses.In addition to various disasters,there are many emergency incidents in life,such as fire,traffic accidents,etc.Once a disaster occurs,the basic network facilities may be destroyed,which means that we lack complete network infrastructure facilities and emergency communication equipments in the complex rescue environment.The results are the failure of information transmission,missing the best time for rescue,and unnecessary losses of human and financial resources of the state.Therefore,a perfect emergency communication system is particularly important.In emergency communication process,a large number of field conditions need to be transmitted in real time.Video information attracts more and more attention due to its large amount of information and intuitive features.By returning video data in real time,the command center can conveniently conduct remote monitoring,commanding and scheduling.Based on the digital terrestrial television broadcasting standard DVB-T2,we design a physical layer scheme for emergency video communication systems.The system has the characteristics of long-distance transmission,wide coverage,high bandwidth,low latency.Compared with the current public network communications,the system has a small number of base stations and a relatively simple structure,and it adopts a point-to-point transmission method and does not need to rely on fixed network devices.This scheme can meet the transmission requirements of emergency video.The specific work is as follows: Firstly,in this thesis,the key technologies in the system are analyzed and modeled,specifically including: the design of the system frame structure,OFDM technology,LDPC coding,decoding technology,system synchronization technology.LDPC decoding algorithm and system synchronization algorithm are the difficulties of this design,and the key part of the algorithms are implemented by MATLAB simulation in order to reduce the complexity of the algorithms,design and implement the hardware algorithm.Secondly,the entire system is simulated on Simulink in order to verify transmission performance at different signal-to-noise ratios.Finally,the hardware implementation of the overall solution is completed.We take Xilinx’s XC7Z020-CLG484 chip as the hardware platform,and use the Verilog language to complete the design of the physical layer,including clock generation module,Ts code stream synchronization module,transmitter-side rate conversion module,scrambling module,BCH coding module,LDPC coding module,bit interleaving module,constellation mapping module,pilot insertion module,OFDM subcarrier mapping module,IFFT transform module,T2 frame framing module and other transmitter parts,and the corresponding demodulation part of the receiver.In addition,we test the transmitter,receiver and overall system,and achieve the development and verification of the entire system to meet the design requirements of this system.更多还原