噪声信道中基于残留冗余的联合信源信道编码

对信源编码中的残留冗余在联合编码中的作用进行了研究,提出了一个在噪声信道中对可变长信源编码码流传输提供有效差错保护的联合信源信道编码方法,该方法利用信源编码器输出中的残留冗余为传输码流提供差错保护。与SayoodK提出的系统相比,该方法是基于改进的联合卷积软解码以及采用非霍夫曼码的通用可变长码,更接近于一般的信源和信道编码方法,并且信源符号集的大小也不受限制。仿真表明,所提出的联合编码方法可获得比传统的分离编码方法更高的性能增益。     

噪声信道中基于残留冗余的联合信源信道编码.

对信源编码中的残留冗余在联合编码中的作用进行了研究，提出了一个在噪声信道中对可变长信源编码码流传输提供有效差错保护的联合信源信道编码方法，该方法利用信源编码器输出中的残留冗余为传输码流提供差错保护。与Sayood K提出的系统相比，该方法是基于改进的联合卷积软解码以及采用非霍夫曼码的通用可变长码，更接近于一般的信源和信道编码方法，并且信源符号集的大小也不受限制。仿真表明，所提出的联合编码方法可获得比传统的分离编码方法更高的性能增益。     

二元对称信道上均匀无记忆信源的信源-信道联合编码的研究

在传统通信系统中,信源编码与信道编码是分别考虑的。但是,在实际中发现,用某种“特定”方法连接起来的最优信源编码器和信道编码器,并不一定能构成最佳通信系统。因此出现了实现通信系统整体优化的“信源信道联合编码”理论。本文主要以数字传输中二元对称信道(BSC)为例,研究了此信道上的信源和信道编码的联合设计。     

基于H.264率失真模型的无线信源信道联合编码方案

针对H.264编码器的率失真特性,建立了一种新的H.264编码率失真(R-D,rate-distortion)模型:然后基于该R-D模型和Turbo码的抗差错特性,对无线环境下的端到端视频传输失真进行了深入的分析,提出了一种无线信道下的自适应视频信源信道联合编码(JSCC,joint source channel coding)方案,该方案可以自适应地根据当前无线信道的具体状况,将网络可用带宽在信道编码和信源编码之间进行最优的分配,使得端到端的传输失真达到最小.实验结果表明,与固定选择信道编码速率方案相比,该方案可以显著提高传输的可靠性,在接收端可以获得更好的视频重建质量.     

基于多描述的联合信源信道编码

在实时通信系统中,传统的联合信源信道编码方法在分组编码长度有限的情况下,不可避免地会存在残余误差,从而影响了整体性能。提出了一种基于多描述源编码的联合信源信道编码方法,此方法不仅可以利用分组编码的纠错能力,也可以利用多描述源编码的鲁棒性。通过具有代表性的高斯信号编码序列在有损网络信道中的传输仿真,可以看出,此方法相对于传统的联合信源信道编码方法,可提供更好的信噪比性能。     

基于Markov信源和LDPC编码的信源信道联合译码算法

本文通过利用Markov信源的冗余信息,提出了一种基于系统LDPC码编码器的信源信道联合译码算法（JSCD）。仿真结果显示,当信源中存在更多的冗余信息时,该JSCD算法可相应取得更好的系统性能。     

基于深度联合信源信道编码的CSI反馈技术

提出了一种基于深度联合信源信道编码的信道状态信息（CSI）反馈方法。该方法使用非线性编码对原始的CSI信息进行降维，之后使用多层网络生成信道输入符号，并利用注意力机制实现了针对信道噪声的自适应功能。与现有CSI压缩反馈方法相比，得益于信源和信道的深度联合编码，该方法可以在有限的带宽下获得更好的预编码任务的性能。此外，所提的方法可使用近似量化方法将复信道输入符号转换为有限的星座点符号，能够与现代移动通信系统有效兼容。     

基于LDPC码的小波图像传输码率优化

LDPC码是一种具有低复杂度,强纠错能力的信道分组编码结构,SPIHT算法是嵌入式小波图像压缩编码中性能较好的一种。文中充分考虑SPIHT算法和LDPC码的特性,提出了根据信源编码后的数据在解码重建时的重要程度进行不等纠错保护的信源信道联合编码方案。实验表明,该方案有利于压缩图像在噪声信道上的可靠传输,提高系统整体纠错性能。     

基于MPEG-4的视频联合信源信道编码

该文提出了一种用于提高MPEG-4码流在噪声信道下的抗误码性能的联合信源信道编码方法。该方法将MPEG-4基本层按重要性进行码流重排后进行交织打包,并根据率失真函数将基本层纹理信息进一步划分为多个子层。编码器根据反映信道状态的反馈信息动态地调整传输的子层数目和每个子层的纠错强度(信道编码速率),使得系统失真最小。仿真结果表明,该方法明显优于未保护的MPEG-4方法,在相同信道带宽及丢包率条件下比等纠错保护的MPEG-4编码方法获得更加稳定的性能。同时由于该方法根据反馈的出错分组数进行传输子层数和纠错强度的联合优化,与Puri等人提出的按照确定信道条件设计目标函数进行优化的MDFEC方法相比,更能够适应信道条件的变化,从而获得更高的性能。     

采用网络编码的双向中继信道中软信息的传输方法

采用格栅编码量化(TCQ)这一信源编码方法结合格栅编码调制(TCM)技术,解决了双向中继信道中软信息的传输问题。仿真表明,在衰落信道下,该方法性能上优于传统的译码转发和放大转发的网络编码方法。该方法应用于双向中继信道并在有限带宽的情况下可获得接近理想信道的链路性能。该方法为软信息网络编码走向实用提供了一种有效的思路。     

A constrained joint source/channel coder design

The design of joint source/channel coders in situations where there is residual redundancy at the output of the source coder is examined. It has previously been shown that this residual redundancy can be used to provide error protection without a channel coder. In this paper, this approach is extended to conventional source coder/convolutional coder combinations. A family of nonbinary encoders is developed which more efficiently use the residual redundancy in the source coder output. It is shown through simulation results that the proposed systems outperform conventional source-channel coder pairs with gains of greater than 9 dB in the reconstruction SNR at high probability of error     

Iterative decoding of serially concatenated arithmetic and channel codes with JPEG 2000 applications.

In this paper, an innovative joint-source channel coding scheme is presented. The proposed approach enables iterative soft decoding of arithmetic codes by means of a soft-in soft- out decoder based on suboptimal search and pruning of a binary tree. An error-resilient arithmetic coder with a forbidden symbol is used in order to improve the performance of the joint source/channel scheme. The performance in the case of transmission across the AWGN channel is evaluated in terms of word error probability and compared to a traditional separated approach. The interleaver gain, the convergence property of the system, and the optimal source/channel rate allocation are investigated. Finally, the practical relevance of the proposed joint decoding approach is demonstrated within the JPEG 2000 coding standard. In particular, an iterative channel and JPEG 2000 decoder is designed and tested in the case of image transmission across the AWGN channel.     

Joint source/channel coding for multiple images

A joint source/channel coding algorithm is proposed for the transmission of multiple image sources over memoryless channels. The proposed algorithm uses a quality scalable image coder to optimally allocate a limited bit budget among all the sources to achieve the optimal overall distortion reduction for the multiple reconstructed images. In addition to the conventional un gain, it provides channel multiplexing gain, which can be much more significant. Furthermore, an extended scheme is proposed to provide flexibility between the optimization performance and complexity.     

Use of residual redundancy in the design of joint source/channelcoders

A technique for providing error protection without the additional overhead required for channel coding is presented. The authors start from the premise that, during source coder design, for the sake of simplicity or due to imperfect knowledge, assumptions have to be made about the source which are often incorrect. This results in residual redundancy at the output of the source coder. The residual redundancy can then be used to provide error protection in much the same way as the insertion of redundancy in convolutional coding provides error protection. The authors develop an approach for utilizing this redundancy. To show the validity of this approach, the authors apply it to image coding using differential pulse code modulation (DPCM), and obtain substantial performance gains, both in terms of objective and subjective measures     

A-law pulse-code modulation by a delta-modulation technique

An A-law pulse-code-modulation coder is described which is composed of a delta modulator and an adaptive binary counter. The coder has a clock rate of 2.048 Mbit/s and has been conceived for the 30/32-channel system.     

Joint Channel Coding Based on Principal Component Analysis

This paper proposes a new joint channel coding algorithm based on principal component analysis. A conventional joint channel coder using passive downmixing undergoes a reduction of both the primary‐to‐ambient energy ratio (PAR) of the downmix signal and the panning gain ratio of the primary source. The proposed system preserves the PAR of the downmix signal by using active downmixing which reflects spatial characteristic. The proposed system also improves the accuracy of the panning gain ratio estimation. Computer simulations and subjective listening tests verify the performance of the proposed system.     

Joint source-channel coding using real BCH codes for robust image transmission.

In this paper, a new still image coding scheme is presented. In contrast with standard tandem coding schemes, where the redundancy is introduced after source coding, it is introduced before source coding using real BCH codes. A joint channel model is first presented. The model corresponds to a memoryless mixture of Gaussian and Bernoulli-Gaussian noise. It may represent the source coder, the channel coder, the physical channel, and their corresponding decoder. Decoding algorithms are derived from this channel model and compared to a state-of-art real BCH decoding scheme. A further comparison with two reference tandem coding schemes and the proposed joint coding scheme for the robust transmission of still images has been presented. When the tandem scheme is not accurately tuned, the joint coding scheme outperforms the tandem scheme in all situations. Compared to a tandem scheme well tuned for a given channel situation, the joint coding scheme shows an increased robustness as the channel conditions worsen. The soft performance degradation observed when the channel worsens gives an additional advantage to the joint source-channel coding scheme for fading channels, since a reconstruction with moderate quality may be still possible, even if the channel is in a deep fade.     

On source coding, channel coding and spreading tradeoffs in a DS-CDMA system operating over frequency selective fading channels with narrowband interference

For a fixed total bandwidth expansion factor, we consider the problem of optimal bandwidth allocation among the source coder, the channel coder, and the spread-spectrum unit for a direct-sequence code-division multiple-access system operating over a frequency-selective fading channel with narrowband interference. Assuming a Gaussian source with the optimum scalar quantizer, and a binary convolutional code with soft-decision decoding, and further assuming that the self-interference is negligible, we obtain both a lower and an upper bound on the end-to-end average source distortion. The joint three-way constrained optimization of the source code rate, the channel code rate, and the spreading factor can be simplified into an unconstrained optimization problem over two variables. Upon fixing the channel code rate, we show that both upper and lower bound-based distortion functions are convex functions of the source code rate. Because an explicit solution for the optimum source code rate, i.e., one that minimizes the average distortion, is difficult to obtain, computer-based search techniques are employed. Numerical results are presented for the optimum source code rate and spreading factor, parameterized by the channel code rate and code constraint length. The optimal bandwidth allocation, in general, depends on the system and the channel conditions, such as the total number of active users, the average jammer-to-signal power ratio, and the number of resolved multipath components together with their power delay profile.