【作者】 陈乐；

【导师】 王太君；

【作者基本信息】 东南大学 ， 信号与信息处理， 2005， 硕士

【摘要】 30MHz以下频段的广播通信系统相对于其他频段广播通信系统有着自己独特的优势。当前我国30MHz以下频段的调幅广播采用模拟系统,而欧洲已于2003年6月正式开通数字调幅广播。出于发展的需要和竞争的压力,我国进行调幅广播数字化改造势在必行。信道纠错编码是数字调幅广播系统的关键技术之一。根据欧洲电信标准化委员会提供的数字调幅广播系统说明书可知,该系统采用的信道编码方案是一套基于删除卷积码的多级编码和调制的组合方案,它机制灵活,可以针对不同的数据通道和不同的信道条件选择不同码率的分量码和星座图。本文在Matlab上建立DRM仿真平台,全面实现了标准中提出的信道编码方案,着重测试DRM系统中MSC通道多级编码方案的误码性能。我们选择标准中B鲁棒模式,10kHz带宽,标准64QAM调制方式,三级分量码率分别为1/4、1/2、3/4,总体码率为1/2的多级编码方案,针对并行译码、迭代多级译码、软判决、硬判决等几种不同的译码方案进行性能分析比较。仿真结果表明,采用软判决迭代多级译码方法的信道编码方案可以较好的改善现有仿真系统的误符号率。在达到相同的误符号率的情况下,此信道编码方案在高斯信道和莱斯信道中可以分别获得4.5和9.5dB的增益。另外通过仿真采用标准64QAM调制和对称分级64QAM调制两种调制方式的多级编码方案的各分量码的误码性能,可以看出多级编码方案具有不等差错保护的特性。本文首先介绍课题的背景意义,以及数字无线电组织提供的数字调幅广播系统标准。接着介绍了通信系统信道编码任务、原理、常用形式,着重介绍了编码调制技术。第三章给出了DRM标准中的信道编码的方案和各个模块的实现方法,其中包括能量扩散、数据流分割、分量码编码、比特交织、星座映射以及符号交织。接着在matlab上建立仿真平台进行性能分析比较和说明,并计算系统的频带利用率。最后对全文进行总结,提出后继工作的一个问题,和以后的工作方向。更多还原

【Abstract】 Comparing to other frequency band broadcasting systems, the one under 30MHz has unique superiority. The AM broadcasting system under 30MHz in our country is a analog system, while it has established a digital one in Europe since June, 2003. Because of the need of development and the pressure of competition, it is imperative to carry on the digital transformation in our country. Channel coding is one of the key technique of digital AM broadcasting system. According to the system specification of DRM given by ETSI, the channel coding scheme applied to the system is a set of combination schemes of the multilevel coding and modulation. It is a flexible mechanism which makes it possible to choose different coding method and constellation according to different data channel or channel condition.Simulation platform is established in matlab to realize the channel coding scheme described in the standard of DRM. One of the channel coding scheme is choosen to research. In this scheme robustness B, spectrum of 10kHz, SM64QAM, total rate of 1/2 is used. Decoding performances of PDL, iMSD, hard-decision and soft-decision are compared and analyed. The simulation shows that this channel coding scheme with soft-decision and iterative multilevel coding could preferably improve the symbol error rate. It can obtain a gain of 4.5dB in channel of Gauss and 9.5dB in channel of Rice. Additionally, performance of bit error rate of component code with SM64QAM and HMsym64QAM is tested. It is concluded that the multilevel coding scheme has specific property of unequal error protection.The background and significance of this project are introduced in the beginning of the paper. Then the channel coding’s task, principle, common forms are introduced, the concept of coding modulation technique are introduced on emphasis. The channel coding scheme is introduced and realization of modules are given in Chapter 3, including energy dispersal, partition of bitstream, component encoding, bit interleaving, signal constellation and mapping, MSC cell interleaving. The performance is analysed, the property of the multilevel coding scheme is explained and the system frequency band efficiency is calculated. Summarize is given in the end, which includes a technical problem and the orientation of the next work.更多还原