DVB-NGH系统关键技术研究与实现

发布时间：2018-05-30 23:25

本文选题：DVB-NGH + 非规则星座　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：随着无线通信技术的高速发展,数字移动通信已成为未来通信发展的主流趋势,另外,用户对移动多媒体业务需求的急剧增长,使得数字视频广播具有非常广泛的应用前景。目前,基于第二代数字地面视频传输标准DVB-T2(Digital Video Broadcasting:2nd Generation Terrestrial)的下一代手持终端演进标准DVB-NGH(Digital Video Broadcasting:Next Generation Handheld)已成为业内正在研究的一个热点。DVB-NGH是第一个引入了MIMO(Multiple Input Multiple Output,多输入多输出)天线机制的广播系统,与以往标准相比,DVB-NGH将在网络承载能力方面有很大提高。尽管DVB-NGH还未正式标准化,但随着新技术的不断引入以及市场需求的强大驱动,DVB-NGH必然会对便携/手持终端的多媒体业务起到巨大的推动作用。本文对DVB-NGH系统部分关键技术进行了详细研究,所取得的主要研究成果为:1.在广泛总结国内外移动多媒体广播技术背景和最新进展的前提下,论文详细介绍了研究DVB-NGH系统的背景和意义,并着重分析了DVB-NGH规范计划引入的一些新的性能增强技术。主要包括:比特交织编码调制、时频分片技术、逻辑组帧与未来扩展帧捆绑、物理层信令、单频网络中的本地业务插入技术以及增强的单频网络MISO机制等。除此之外,还简单介绍了DVB-NGH MIMO规范所采用的关键技术及其实现框架。2.研究了DVB-NGH系统中可提高分集增益的非规则星座和四维旋转星座。非规则星座主要包括非规则64-QAM与非规则256-QAM,其基本原理是使得原有的规则星座准高斯化,以期能够缩小规则星座容量限与香农容量限之间的差距。在AWGN信道下,非规则64-QAM的平均误比特率BER(Bit Error Ratio)相比于64-QAM有最大0.5dB的性能提升,非规则256-QAM相比于256-QAM在不同码率下具有0.4dB到0.9dB的性能增益。四维旋转是将一个符号在四维尺度上进行拓展,使得符号整体经历深衰落的概率大大降低。本文针对四维旋转提出了一种新的解调方法,该方法基于MAP(Maximum A Posteriori,最大后验)算法,并利用联合概率求解软信息。仿真表明,在瑞利衰落信道下,当LDPC(Low Density Parity Check,低密度校验码)译码前误码率为10-3时,四维旋转QPSK相比于二维旋转大约有4dB的性能改善,相比于无旋转星座性能提高了大约14dB。LDPC译码后的性能在高码率时能够提供0.5~0.6dB的增益,在低码率时几乎无增益,同时为了避免过多地增加接收端复杂度,DVB-NGH仅在码率高于8/15时对QPSK调制采用四维旋转。3.对本地节目插入技术的研究。在分析了DVB-NGH中的两种本地节目插入方法——分层本地业务插入技术(H-LSI)和正交本地业务插入技术(O-LSI)的基础上,本文提出了一种新的本地节目插入方法,该方法基于协同Alamouti编码方案和唯一可分解星座对技术,利用对全局信号进行旋转的方式来插入本地业务。接收端采用一种联合解调方法,即在旋转与不旋转两种情况下对接收信号进行最大似然检测并比较两情况下的欧氏距离来估计插入的本地信号。该方法无需增加额外的时间或频率资源就可以提高信道利用率,尤其在高信噪比条件下,相比于无本地业务插入系统其资源利用率提高了0.5bpcu。4.对DVB-NGH MIMO规范进行了研究。DVB-NGH是第一个引入了MIMO机制的广播系统。对于DVB-NGH MIMO的实现,发送端主要采用了增强空间复用技术加相位跳变技术,接收端可根据具体要求采取不同的检测方法。本文简要介绍了几种可选的MIMO检测方法,分析了各个方法的实现复杂度,并选择迫零检测方法与采用相同检测方法的SISO系统与MISO系统的性能做了相应的仿真对比。同时就MIMO预编码相关参数对性能的影响也做了相应仿真。结果表明,在相同的频谱利用率条件下,相比于MISO和SISO机制,MIMO能够提供更高的性能增益。
[Abstract]:With the rapid development of wireless communication technology, digital mobile communication has become the mainstream trend of future communication development. In addition, the rapid growth of users' demand for mobile multimedia services makes digital video broadcasting have a very wide application prospect. At present, the standard DVB-T2 (Digital Video Broadcas) is based on the ground video transmission standard of second algebra words. Ting:2nd Generation Terrestrial) the next generation of handheld terminal evolution standard DVB-NGH (Digital Video Broadcasting:Next Generation Handheld) has become a hot spot in the industry, and.DVB-NGH is the first broadcast system introduced into the antenna mechanism of MIMO (Multiple), multiple input and multiple output (multiple input and multiple output), and the previous standards In contrast, DVB-NGH will greatly improve the capacity of the network. Although DVB-NGH is not formally standardized, with the continuous introduction of new technology and the strong drive of market demand, DVB-NGH will inevitably play a great role in promoting the multimedia services of portable / handheld terminals. This article has made a detailed study of some key technologies of the DVB-NGH system. The main achievements of the research are as follows: 1. the background and significance of the study of DVB-NGH system are introduced in detail, and some new performance enhancement techniques introduced by the DVB-NGH specification plan are analyzed in detail. Modulation, time frequency division, logical group frame and future extended frame binding, physical layer signaling, local service insertion in single frequency network and enhanced single frequency network MISO mechanism. Besides, it also briefly introduces the key technologies used by the DVB-NGH MIMO specification and its actual framework.2. to improve diversity and increase in the DVB-NGH system. Non regular constellations and four-dimensional rotation constellations. Irregular constellations mainly include irregular 64-QAM and irregular 256-QAM. The basic principle is to make the original rule constellation quasi Gauss, in order to reduce the gap between the rule constellation capacity limit and the Shannon capacity limit. Under the AWGN channel, the average bit error rate BER (Bit Er) of the irregular 64-QAM (Bit Er) Ror Ratio) has the maximum performance enhancement of 0.5dB compared to 64-QAM, and the irregular 256-QAM has the performance gain of 0.4dB to 0.9dB at different bit rates compared to 256-QAM. The four-dimensional rotation is to extend a symbol on the four-dimensional scale, which greatly reduces the probability of the symbol overall experience deep fading. This paper presents a new kind of new type of rotation for the four-dimensional rotation. The method is based on the MAP (Maximum A Posteriori, maximum posteriori) algorithm, and the joint probability is used to solve soft information. The simulation shows that in the Rayleigh fading channel, when the error rate of the LDPC (Low Density Parity Check, low density parity check code) before the decoding is 10-3, the four-dimensional rotation QPSK has approximately 4dB performance improvement compared to the two-dimensional rotation. Compared with the performance of non rotation constellation, the performance of about 14dB.LDPC decoding can provide 0.5~0.6dB gain at high bit rate, almost no gain at low bit rate, and in order to avoid excessive increase in receiver complexity, DVB-NGH only uses four dimensional rotation.3. for QPSK modulation for local program insertion technology when the bit rate is higher than 8/15. In this paper, based on the analysis of two local program insertion methods in DVB-NGH - layered local service insertion (H-LSI) and orthogonal local service insertion (O-LSI), a new method of local program insertion is proposed. This method is based on a cooperative Alamouti coding scheme and unique decomposable constellation. The local signal is inserted in a way of rotation. The receiver uses a joint demodulation method, that is, the maximum likelihood detection of the received signal in two cases of rotation and non rotation, and the Euclidean distance in the two case to estimate the inserted local signal. This method does not require additional time or frequency resources to be added. Improving the utilization of channel, especially in high signal to noise ratio, compared with the resource utilization of non local service insertion system, 0.5bpcu.4. has improved the DVB-NGH MIMO specification..DVB-NGH is the first broadcast system introducing MIMO mechanism. For the implementation of DVB-NGH MIMO, the sending end mainly uses enhanced space multiplexing technology. The receiver can take different detection methods according to specific requirements. This paper briefly introduces several optional MIMO detection methods, analyzes the complexity of the implementation of each method, and chooses the zero forcing detection method to compare the performance of the SISO system with the MISO system with the same detection method. At the same time, MIMO The effects of precoding parameters on performance are also simulated. The results show that, under the same spectrum utilization conditions, compared with the MISO and SISO mechanisms, MIMO can provide higher performance gain.
【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】：TN934

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