ATSC DTV的移动接收技术

文章从改进ATSC标准、引进自适应阵列天线技术和提出快速均衡算法三方面论述了提高ATSC DTV移动接收性能的方法.通过仿真验证了这些方法的有效性.     

ATSC Terrestrial Digital Television Broadcasting Using Single Frequency Networks

In this paper, we propose an efficient method to broadcast digital television signals using single frequency networks (SFNs) within the Advanced Television Systems Committee (ATSC) transmission systems. In implementing the SFNs of an 8‐vestigial side band (8‐VSB) Digital Television (DTV) system, the ambiguity problem of the trellis coder is unavoidable in a conventional ATSC transmission system. We propose a memory initialization of the trellis coder to resolve this ambiguity problem. Since the proposed scheme to synchronize multiple transmitters minimizes the changes from the conventional ATSC system, the hardware complexity for these changes is very low. Our simulation results show that the proposed scheme makes a less than 0.1 dB degradation at the threshold of visibility with a bit error rate of 3×10^?6 in the additive white Gaussian noise (AWGN) channel. It is possible to reduce the performance degradation by increasing the initialization period of the proposed scheme.     

An efficient decision feedback equalizer for the ATSC DTV receiver

In this paper an efficient decision feedback equalizer is presented for the equalization of the received signal in the eight level vestigial sideband, Advanced Television Systems Committee, digital television system, adopting a novel detection rule for symbol detection at the output of the equalizer. The conventional hard limiter is replaced by an efficient symbol detection algorithm, based on the underlying trellis coded modulated coding of the transmitted symbols. The proposed decision device has a marginal computational cost and it can be implemented using simple combinatorial and sequential logic circuitry. When the equalizer operates in the decision directed mode, the normalized least mean squared algorithm is utilized for the adaptation of the equalizer coefficients, in a “stop-and-go” like mode, triggered by a reliability signal associated to the detected symbols. The performance of the proposed method is illustrated by typical computer simulation.     

ATSC DTV系统中TCM编译码器的实现和简化

对ATSC DTV 8 VSB系统调制器中数据处理部分进行分析,给出一种硬件实现方案。采用一个2/3码率的TCM编码器代替ATSC标准中12支路并行的编码器,并自然地插入了同步数据,从而降低了系统复杂度。针对系统中TCM译码器,提出一种可变译码深度的译码方法,简化了系统的控制。结合联合均衡和TCM译码技术,提出多重深度译码的方法,降低了错误传播对判决反馈均衡器的影响,从而提高均衡器的性能。     

Near‐Optimum Blind Decision Feedback Equalization for ATSC Digital Television Receivers

This paper presents a near‐optimum blind decision feedback equalizer (DFE) for the receivers of Advanced Television Systems Committee (ATSC) digital television. By adopting a modified trellis decoder (MTD) with a trace‐ back depth of 1 for the decision device in the DFE, we obtain a hardware‐efficient, blind DFE approaching the performance of an optimum DFE which has no error propagation. In the MTD, the absolute distance is used rather than the squared Euclidean distance for the computation of the branch metrics. This results in a reduction of the computational complexity over the original trellis decoding scheme. Compared to the conventional slicer, the MTD shows an outstanding performance improvement in decision error probability and is comparable to the original trellis decoder using the Euclidean distance. Reducing error propagation by use of the MTD in the DFE leads to the improvement of convergence performance in terms of convergence speed and residual error. Simulation results show that the proposed blind DFE performs much better than the blind DFE with the slicer, and the difference is prominent at the trellis decoder following the blind DFE.     

数字电视数据广播系统设计

介绍了数字电视数据广播系统的技术基础,提出了一套数据广播服务器硬软件系统设计方案。     

A Novel Clock Recovery Scheme for ATSC Receivers

This paper presents a method of using the field sync signal to perform clock recovery for ATSC receivers. This approach ensures a fast, reliable, and accurate receiver clock recovery even under severely distorted channel conditions.     

Quality Enhancement for Hybrid 3DTV with Mixed Resolution Using Conditional Replenishment Algorithm

This paper proposes a conditional replenishment algorithm (CRA) to improve the visual quality (where spatial resolutions of the left and right views are mismatched) of a hybrid stereoscopic 3DTV that is based on the ATSC‐M/H standard. So as to generate an enhanced view, the CRA is to choose the better substitute among a disparity‐compensated view with high quality and a simply interpolated view. The CRA generates a disparity map that includes modes and disparity vectors as additional information. It also employs a quad‐tree structure with variable block size by considering the spatial correlation of disparity vectors. In addition, it takes advantage of the disparity map used in a previous frame to keep the amount of additional information as small as possible. The simulation results show that the proposed CRA can successfully improve the peak signal‐to‐noise ratio of a poor‐quality view and consequently have a positive effect on the subjective quality of the resulting 3D view.     

市县共享数字电视平台的技术方案

以湖州市与所属3县共享数字电视平台为例，从技术角度叙述了市县共享数字电视平台的技术方案，从业务层面阐述了广播电视网络资源共享，以减少重复投资，在共享一个技术平台的基础上争取利益最大化，真正把广电网络做大做强，为广电今后的发展打下良好的基础。     

数字电视地面传输标准ISDB-T系统传输方案

对日本数字广播专家组制定的数字电视地面传输标准ISDB-T系统传输方案进行了描述,首先简要介绍了系统的传输方式及系统参数,然后给出了信道编码、调制方式以及接收机部分的具体结构.同时,由于ISDB-T和DVB-T系统均采用OFDM调制技术,所以对两者进行了比较.     

级联格状编码传输方案在数字HDTV中的应用研究

本文首先对地面广播信道的各种干扰进行分析。研究级联格状编码方案在ＨＤＴＶ中应用的设计要求。提出用于ＨＤＴＶ地面数字传输系统的级联８状态ＴＣＭ３２ＱＡＭ和ＲＳ码方案，并对其性能进行计算机模拟。最后分析ＨＤＴＶ的突然中断效应和数字传输系统性能的关系。     

一种基于速率控制的反向链路分组数据新传输方案

该文介绍了在CDMA2000 中反向链路数据传输采取的速率控制机制;然后提出了一种在CDMA2000 1x Release C系统中实现该机制的方案。通过分析和系统仿真可知,该方案有利于提高反向链路的数据吞吐量,又能保持RoT(Rise-over-Thermal)的稳定,而且所需的时延相对于调度方式要小,能较好地适应对时延敏感业务的要求。     

A Novel Secure Data Transmission Scheme in Industrial Internet of Things

The industrial Internet of Things(IoT)is a trend of factory development and a basic condition of intelligent factory.It is very important to ensure the security of data transmission in industrial IoT.Applying a new chaotic secure communication scheme to address the security problem of data transmission is the main contribution of this paper.The scheme is proposed and studied based on the synchronization of different-structure fractional-order chaotic systems with different order.The Lyapunov stability theory is used to prove the synchronization between the fractional-order drive system and the response system.The encryption and decryption process of the main data signals is implemented by using the n-shift encryption principle.We calculate and analyze the key space of the scheme.Numerical simulations are introduced to show the effectiveness of theoretical approach we proposed.     

一种多媒体数据可靠传输策略

针对UDP数据报传输不可靠性这一问题,提出一种主动防止数据报丢失的策略。该策略在编码端分片传输UDP数据报,在接收端利用环形缓冲区接收并重组各数据报分片。这种策略不仅有效地避免了接收端多个数据报片冲突以及接收缓冲区溢出等现象的出现,而且减小了数据报片丢失和乱序对解码图像质量的影响,使得恢复的图像质量有明显改善。     

Reciprocal Data Map Coding Scheme for Image Transmission in MIMO-OFDM Systems

Wireless Personal Communications - An improved error correction code using Iterative decoding involves the substitution of extrinsic probabilities among the main decoders. The output of...     

基于卷积神经网络自编码器结构的空时分组传输方案

为提高现有端到端通信系统的泛化能力和可靠性,提出了一种基于卷积神经网络的空时分组码(Space-Time Block Coding,STBC)多输入多输出通信系统物理层方案。该方案将通信系统物理层表述、调制和解调过程联合起来形成端到端自编码器系统,引入多层一维卷积层,分别构建发射机和接收机,并扩展为多天线模式。为进一步提高系统可靠性,合理规划网络结构和参数,联合信号的调制和编码方案,优化了系统模型。仿真实验表明,针对瑞利相关衰落下多输入多输出(MultipleInput Multiple-Output,MIMO)信道应用场景,训练模型可以实现传统STBC系统的误码性能,两发两收系统在发送端相关系数为0和0.9时分别优于传统系统0.5 dB和1 dB。此外,经过优化后的系统可获得采用卷积编码的性能改善效果,其两发两收不同工作方式优于传统1/2码率卷积编码STBC系统1～3 dB。     

m序列复合码的一种快速相关算法

在直扩系统中,PN码的快速捕获十分重要。由于m序列的优选对有限,故在实际应用中采用复合码作为PN 码。常用的复合码主要有Gold序列和Kasami小集合序列。本文提出了一种利用快速沃尔什变换(FWT)实现对复合码进行快速相关的算法。这种算法适用于由两个m序列模2加形成的复合码,并原则上可以推广到Kasami大集合序列的捕获上。分析表明,我们提出的算法与传统相关算法相比,降低了算法的时间复杂度。     

MIMO-OFDM系统速率自适应传输方案

在采用TDD工作方式的MIMO-OFDM实际通信系统中,由于收发两端环境的不同导致干扰对称的假设不再满足。为了弥补这一影响,准确地确定系统的最佳传输参数,提出了一种基于事件驱动机制的闭环自适应传输方案。该方案通过在收发双方建立一条闭环控制信息传输链路,实现了迅速准确地确定最佳传输参数的目的。实验仿真结果表明,当在MIMO-OFDM系统中采用该方案时,可以有效提高系统的吞吐量,减小系统的中断概率。     

一种新的二值图像密写方法

二值图像只有黑白两种颜色,密写时孤立地考虑单个象素嵌入信息容易引起图像质量的下降.本文提出一种新的针对二值图像的密写方法.该方法根据象素的空间邻域特性,将秘密信息嵌入在黑白交替的区域,从而使得视觉上不能察觉秘密信息的存在.嵌入信息时由密钥决定象素的遍历顺序,可使信息在整个图像空间内均匀分布,有效地避免了局部失真过大.实验表明该算法具有实现简单、嵌入信息量大、图像失真小的优点.