共查询到20条相似文献,搜索用时 125 毫秒
1.
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。 相似文献
2.
3.
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。 相似文献
4.
对信源信道自适应联合编码方法进行了研究,提出了一种新的基于纠错算术码的联合信源信道编解码系统。该系统在编码端利用算术码内嵌禁用符号实现信源信道一体式编码,即利用马尔科夫信源模型和根据信道状态信息自适应地调整禁用符号概率大小从而调整编码码率来实现信道自适应;在解码端,推导出了基于MAP的解码测度数学公式并基于此测度公式提出了一种改进的堆栈序列估计算法。与传统的信道自适应编码算法不同,该自适应编码算法只需调整一个参数:禁用符号,且理论上可获得连续可变的编码码率。实验结果表明,与经典的Grangetto联合编码系统以及分离编码系统相比,所提出的编码系统具有明显改善的性能增益。 相似文献
5.
6.
针对自同步扰码系统的联合信源信道译码问题,本文将自同步扰码看作一种特殊的卷积编码,提出了类似卷积译码的软输入软输出(SISO)自同步去扰算法。该算法利用信源冗余更新扰码序列的外信息,在信道译码时作为先验信息进行译码,实现了自同步去扰与信道译码之间的软信息交互,充分利用了信源冗余信息,使得接收系统的性能得到了有效提升。仿真结果表明,在TPC编码条件下,当信源冗余度为70%时,联合信源信道译码的性能增益约为4.1dB。相比于单一纠错编码系统,当通信系统中存在自同步扰码时,联合信源信道译码具有更大的性能增益。 相似文献
7.
8.
9.
10.
由于算法复杂度和延迟的限制,语音编码参数仍然保留了一定的冗余信息,这些冗余量表现为参数的非等概分布和时间相关性。该文在比特级上利用信源编码参数的冗余信息在软输入、软输出信道解码和信源参数估计之间进行迭代运算,并将此联合解码算法运用于GSM EFR系统。仿真结果表明此算法降低了编码参数的BER,提高了解码语音的信噪比,具有一定的可行性和有效性。 相似文献
11.
Efficient source decoding over memoryless noisy channels using higher order Markov models 总被引:1,自引:0,他引:1
Lahouti F. Khandani A.K. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2004,50(9):2103-2118
Exploiting the residual redundancy in a source coder output stream during the decoding process has been proven to be a bandwidth-efficient way to combat noisy channel degradations. This redundancy can be employed to either assist the channel decoder for improved performance or design better source decoders. In this work, a family of solutions for the asymptotically optimum minimum mean-squared error (MMSE) reconstruction of a source over memoryless noisy channels is presented when the redundancy in the source encoder output stream is exploited in the form of a /spl gamma/-order Markov model (/spl gamma//spl ges/1) and a delay of /spl delta/,/spl delta/>0, is allowed in the decoding process. It is demonstrated that the proposed solutions provide a wealth of tradeoffs between computational complexity and the memory requirements. A simplified MMSE decoder which is optimized to minimize the computational complexity is also presented. Considering the same problem setup, several other maximum a posteriori probability (MAP) symbol and sequence decoders are presented as well. Numerical results are presented which demonstrate the efficiency of the proposed algorithms. 相似文献
12.
13.
为克服无线衰落信道中严重的符号间干扰( ISI)的影响,提出了一种新的利用信源冗余的Turbo均衡算法。该算法将联合信源信道译码技术与Turbo均衡技术结合起来,在均衡、译码、信源之间建立起软信息交互的环路,有效提高了整体接收的性能。外信息传递( EXIT)图分析与计算机仿真均表明,尽管信源冗余给译码器带来的性能提升较为有限,但是将这部分信息反馈回均衡器后,在严重ISI信道,信源冗余度为70%时,整体接收的性能改善约为9.5 dB,基本达到了理想加性高斯白噪声( AWGN)信道下的误码性能。 相似文献
14.
为克服无线衰落信道中严重的符号间干扰(ISI)的影响,提出了一种新的利用信源冗余的Turbo均衡算法。该算法将联合信源信道译码技术与Turbo均衡技术结合起来,在均衡、译码、信源之间建立起软信息交互的环路,有效提高了整体接收的性能。外信息传递(EXIT)图分析与计算机仿真均表明,尽管信源冗余给译码器带来的性能提升较为有限,但是将这部分信息反馈回均衡器后,在严重ISI信道,信源冗余度为70%时,整体接收的性能改善约为9.5 dB,基本达到了理想加性高斯白噪声(AWGN)信道下的误码性能。 相似文献
15.
A constrained joint source/channel coder design 总被引:3,自引:0,他引:3
Sayood K. Fuling Liu Gibson J.D. 《Selected Areas in Communications, IEEE Journal on》1994,12(9):1584-1593
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 相似文献
16.
Spatial multiplexing is used in multiple input multiple output (MIMO) wireless systems to increase the data rate. Some nonlinear detectors, such as minimum mean square error (MMSE) Vertical Bell laboratories layered space-time (VBLAST), Maximum A-Posteriori (MMSE VBLAST MAP), and MMSE Improved VBLAST detectors are used in place of a over more complex detector, such as maximum likelihood detector or singular value decomposition based detector. We have presented simulation results of MIMO symbol error rate versus average SNR for MMSE VBLAST MAP and MMSE Improved VBLAST schemes assuming spatially correlated channels for M-ary QAM. We have observed that the performance of MMSE VBLAST MAP and MMSE Improved VBLAST detectors is almost identical in spatially uncorrelated channels. However, in the case of spatially correlated channels, MMSE Improved VBLAST outperforms MMSE VBLAST MAP. We have also seen that complexity of the Improved VBLAST algorithm is higher than the complexity of VBLAST MAP algorithm. 相似文献
17.
18.
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 相似文献
19.
MMSE analysis of certain large isometric random precoded systems 总被引:1,自引:0,他引:1
Debbah M. Hachem W. Loubaton P. de Courville M. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2003,49(5):1293-1311
Linear precoding consists in multiplying by an N/spl times/K matrix a K-dimensional vector obtained by serial-to-parallel conversion of a symbol sequence to be transmitted. In this paper, new tools, borrowed from the so-called free probability theory, are introduced for the purpose of analyzing the performance of minimum mean-square error (MMSE) receivers for certain large random isometric precoded systems on fading channels. The isometric condition represents the case of precoding matrices with orthonormal columns. It is shown in this contribution that the signal-to-interference-plus-noise ratio (SINR) at the equalizer output converges almost surely to a deterministic value depending on the probability distribution of the channel coefficients when N/spl rarr/+/spl infin/ and K/N/spl rarr//spl alpha//spl les/1. These asymptotic results are used to analyze the impact of orthogonal spreading as well as to optimally balance the redundancy introduced between linear precoding versus classical convolutional coding, while preserving a simple MMSE equalization scheme at the receiver. 相似文献
20.
The assumptions made about the source during source coder design result in a residual redundancy at the output of the source coder. This redundancy can be utilized for error protection without any additional channel coding. Joint source/channel coders obtained using this idea via maximum a posteriori probability decoders tend to fail at low probability of error. In this paper, we propose a modification of the standard approach which provides protection at low error rates as well 相似文献