基于NGB-W系统的LDPC编码技术研究

发布时间：2018-11-07 14:09

【摘要】：在无线通信系统中差错控制编码技术是确保信息能够可靠传输的重要技术之一。低密度奇偶校验码(Low Density Parity Check,LDPC)是性能无限接近香农限的一种纠错码,从第二次发现之后得到了广泛的关注,自信息论提出以来LDPC码凭借着其低译码复杂度、灵活的结构、优异的性能成为编码领域的重大突破之一。目前在深空通信、卫星通信、数字音视频广播等领域LDPC码被广泛应用。广播电视网是目前应用最广泛的大众信息传播载体,方便快捷的将信息传播到广大家庭用户中,随着信息技术的飞速发展,以及人们对无线业务需求的日益增加,传统的广播网和双向通信网已经无法使移动业务最优化,下一代广播电视无线网(Next Generation Broadcast Network Wireless Systems,NGB-W)应运而生。本文结合所在中国科学院上海高等研究院新媒体无线技术研究中心实习所参与的“下一代广播电视无线网(NGB-W)”的项目,主要对该系统中的比特交织编码调制模块(Bit Interleaved Coded Modulation,BICM)进行了深入的研究,并对信道编码所采用的LDPC码的码构造进行了研究学习。本文首先对LDPC码的发展历史和研究现状进行了介绍,对LDPC码的基本原理以及影响LDPC码性能的一些因素进行了简要介绍,并对LDPC码的一些基本译码算法进行了介绍。然后,详细阐述了LDPC码的构造方法,其中包括随机构造和代数构造,虽然由代数构造算法构造出的码有一定的结构规律便于降低编码复杂度,但是代数构造在码长的选择上缺少灵活性,所以本文重点介绍了随机构造算法中的PEG(Progressive Edge Growth)以及基于该算法的改进算法。本文对采用PEG结合ACE(Approximate cycle EMD)的算法构造出NGB-W系统中的LDPC码进行了MATLAB仿真,对其性能进行验证,并在相同的仿真条件下与DVB-T2中的LDPC码进行性能的比较。通过仿真可以看出利用PEG结合ACE的方法构造出的的高码率LDPC码性能优于DVB-T2系统中的LDPC码。
[Abstract]:Error control coding is one of the most important techniques to ensure the reliable transmission of information in wireless communication systems. Low density parity check code (Low Density Parity Check,LDPC) is a kind of error-correcting code whose performance is infinitely close to the Shannon limit. Since the second discovery, the LDPC code has been widely concerned. Since the information theory was put forward, the LDPC code has been constructed with its low decoding complexity and flexible structure. Excellent performance has become one of the major breakthroughs in the field of coding. At present, LDPC codes are widely used in deep space communication, satellite communication, digital audio and video broadcasting and other fields. Radio and television network is the most widely used carrier of mass information dissemination. It is convenient and fast to spread information to the majority of home users. With the rapid development of information technology and the increasing demand for wireless services, radio and television network is the most widely used carrier of mass information. The traditional broadcasting network and bidirectional communication network can not optimize the mobile service, and the next generation radio and television wireless network (Next Generation Broadcast Network Wireless Systems,NGB-W) emerges as the times require. This paper is based on the project "next Generation Radio and Television Network (NGB-W)", which is attended by the Institute of New Media Wireless Technology Research Center of Shanghai Institute of Advanced Research, Chinese Academy of Sciences. In this paper, the bit-interleaved coded modulation module (Bit Interleaved Coded Modulation,BICM) is studied deeply, and the code structure of LDPC code used in channel coding is studied. In this paper, the development history and research status of LDPC codes are introduced, the basic principle of LDPC codes and some factors affecting the performance of LDPC codes are briefly introduced, and some basic decoding algorithms of LDPC codes are introduced. Then, the construction method of LDPC code is described in detail, including random construction and algebraic construction, although the code constructed by algebraic construction algorithm has a certain structure law to reduce the coding complexity. However, algebraic construction lacks flexibility in code length selection, so this paper focuses on the introduction of PEG (Progressive Edge Growth) and the improved algorithm based on the random construction algorithm. In this paper, the LDPC code in NGB-W system is constructed by using the algorithm of PEG and ACE (Approximate cycle EMD), and its performance is verified by MATLAB simulation. The performance of LDPC code in DVB-T2 is compared with that of LDPC code in DVB-T2 under the same simulation conditions. The simulation results show that the high bit rate LDPC codes constructed by PEG combined with ACE have better performance than LDPC codes in DVB-T2 systems.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN911.22

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