基于迭代结构的联合信源信道GSM语音解码

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。     

迭代结构的信源信道联合解码及其简化算法

信源信道联合解码算法中的迭代信道解码需要进行比特似然值和概率值转换,以及联乘、累加运算,增加了信道解码的计算复杂度,该文针对这一问题,直接利用信道解码的比特硬判决值和参数的先验概率,估计比特的外信息,用于迭代信道解码。基于高斯-马尔可夫信源参数的仿真实验表明,该简化算法大大降低了迭代信道解码算法的计算复杂度。与独立解码算法相比,简化的联合解码算法明显改善了接收参数的信噪比,同时不会明显降低原迭代结构解码算法的性能。     

Minimum Terms of Residual Redundancy for Successful Iterative Source-Channel Decoding

Iterative source-channel decoding (ISCD) improves the error robustness of a digital communication system by iteratively evaluating natural residual source redundancy and artificial channel coding redundancy in a TURBO-like process. Based on recent results to extrinsic information transfer (EXIT) charts we present a novel (experimental) approach to quantify the minimum terms of residual redundancy which are needed for (almost) successful ISCD. Moreover, we clarify why in certain situations the decoding trajectory exceeds the EXIT-characteristic of soft decision source decoding (SDSD) in an ISCD scheme     

Iterative Source-Channel Decoding With Markov Random Field Source Models

We propose a joint source-channel decoding approach for multidimensional correlated source signals. A Markov random field (MRF) source model is used which exemplarily considers the residual spatial correlations in an image signal after source encoding. Furthermore, the MRF parameters are selected via an analysis based on extrinsic information transfer charts. Due to the link between MRFs and the Gibbs distribution, the resulting soft-input soft-output (SISO) source decoder can be implemented with very low complexity. We prove that the inclusion of a high-rate block code after the quantization stage allows the MRF-based decoder to yield the maximum average extrinsic information. When channel codes are used for additional error protection the MRF-based SISO source decoder can be used as the outer constituent decoder in an iterative source-channel decoding scheme. Considering an example of a simple image transmission system we show that iterative decoding can be successfully employed for recovering the image data, especially when the channel is heavily corrupted.     

基于MS估计和迭代结构的信源信道联合解码系统性能分析

该文对基于均方MS(Mean Square)误差最小准则估计的软输入信源解码和基于信源参数特性及迭代结构的维特比解码两种信源信道联合解码算法进行分析,分别给出系统性能提高的影响因子,同时与信源信道独立解码算法相比较,并推导了联合算法中的接收参数信噪比的提高幅度以及比特误码率的上限值,证明了联合解码算法的可行性和有效性。实验仿真结果表明了分析方法的正确性。     

迭代译码的级联Reed-Solomon乘积码与卷积码

该文提出用Reed Solomon(RS)乘积码作为外码,卷积码作为内码的级联码方案并且内外码间用Congruential向量生成的交织图案对RS码符号进行重排列。对此级联码采用的迭代译码基于成员码的软译码算法。当迭代次数达到最大后,通过计算RS码的校正子,提出一种纠正残余错误的方法,进一步提高了系统的误比特性能。仿真结果表明,在AWGN信道中与迭代译码的级联RS/卷积码相比,当误比特率为1e-5时,新系统的编码增益大约有0.4 dB。     

可快速迭代解码的非相干空时编码

提出了一种基于满分集准正交空时分组码构造非酉非相干空时码的方法,该编码能够最大限度地利用信道的相关时间来提高码率.根据代数分集的定义,证明了所构造的编码可获得满代数分集.为了能够充分利用编码的准正交结构简化解码,选用了基于期望最大化的迭代算法对所构造的编码进行解码,该算法能够极大地减小最优解码器的复杂度.仿真结果表明,迭代解码算法可快速收敛且其能够很好地对解码复杂度和误码性能进行折衷.     

Efficient Computation of EXIT Functions for Nonbinary Iterative Decoding

The calculation of nonbinary extrinsic information transfer charts for the iterative decoding of concatenated index-based codes is addressed. We show that the extrinsic information at the output of a constituent a posteriori probability decoder can be calculated with very low complexity, where expensive histogram measurements are not required any more. An example for turbo trellis-coded modulation demonstrates the capabilities of the proposed approach     

Modified Iterative Decoding Algorithm for Polar Code Using Maximum Likelihood Estimation

The key challenges in real time voice communication in long term evolution mobile are reduction in complexity and latency. Efficient encoding and decoding algorithms can cater to these. The implementation of such polar code based efficient algorithms is proposed in this paper. The overall latency of 3.8 ms is needed to process 8 bit block length. The novel sub-matrix near to identity matrix is presented. This resulted into minimization of loops among least reliable bits due to iterated parity check matrix. Look-up table based memory mapping is used in encoder to reduce latency while Euclidian decoding technique is used in decoder. The number of iterations is reduced by 50%. The experimentation is performed with additive white Gaussian noise and QPSK modulation. The proposed modified iterative decoding algorithm requires SNR of 5.5 dB and 192 computations for targeted bit error rate of 10^?4. The second proposed method needs 9 dB, 2 iterations for 384 computations. The penalty paid is quantization error of 0.63% due to restricting computations to fourth order series of hyperbolic function with same 8 bit block length.     

并行级联分组码的一种新的迭代译码算法

并行级联分组码比串行级联分组码具有更高的码率,基于LLR计算的Turbo迭代译码算法使其内外分量码均做到了软判决译码。通过引入校正因子a（m）,将接收信息与子译码器的输出软信息进行线性叠加反馈能在省去繁琐的LLR计算的情况下实现并行级联分组码的Turbo迭代译码。仿真研究表明,若将译码器的输出进行简单的相关运算,可进一步改善译码器性能。     

An Efficient Algorithm for Soft-Decision Decoding of the (24, 12) Extended Golay Code

An efficient algorithm for soft-decision decoding of the (24, 12) extended Golay code is described. Results obtained for white Gaussian noise are presented which show that performance is only a few tenths of a decibel away from that of an ideal correlator.     

A novel Variable-Length Code for robust video coding

A novel Variable-Length Code （VLC）, called Alternate VLC （AVLC）, is proposed in this letter, which employs two types of VLC to encode source symbols alternately. Its advantage is that it can not only stop the symbol error propagation effect, but also correct symbol insertion errors and avoid symbol deletion errors, so the original sequence number of symbols can be kept correctly, which is very important in video communication.     

LP Decoding for Joint Source-Channel Codes and for the Non-Ergodic Polya Channel

Linear programming (LP) decoding of low-density parity-check codes over discrete memoryless symmetric channels was introduced by Feldman et al. in [1]. Here, we extend the LP decoding paradigm by applying it to two additional scenarios: joint source-channel (JSC) coding and decoding over the infinitememory non-ergodic binary Polya-contagion channel. Simulation results indicate that the JSC LP decoder yields significant gains over the standard LP decoder for non-uniform sources. Simulations also show that the LP decoder for the Polya channel performs moderately well in relation to the ϵ-capacity limit.     

MIMO系统中一种自适应的迭代检测译码算法

针对常用的非穷尽列表形式后验概率检测算法直接采用恒定且较大的列表长度,导致列表冗余度大的问题,该文提出了一种自适应长度的列表球形译码算法(Adaptive Size List Sphere Decoding, ASLSD)。在算法中通过更新检测半径和设置停止条件,使检测列表长度可随信噪比和迭代次数自适应变化。而且通过将列表操作与LSD (List Sphere Decoding)检测相结合,避免了符号序列在不同半径下的重复检测。仿真表明,在较小性能损失的前提下,该算法可以大大减小所需检测列表的长度,进而有效降低接收机的复杂度。     

联合LDPC码的多级编码调制迭代判决仿真分析

论文介绍了多级编码调制的基本原理和译码算法,以LDPC码作为多级编码调制的分量码,在译码过程中引入了迭代思想,分析了一种适用于多级编码调制的迭代判决算法,并建立了MLCM-ID系统模型.计算机仿真表明,该算法能够有效地提高系统性能,具有一定的应用价值.     

Improved Bit-Based Joint Source-Channel Decoding of Variable Length Codes

Joint source channel decoding (JSCD) for variable length codes (VLCs) has been shown to be effective for error- prone channels. In this paper, we propose two schemes to enhance the performance of the existing bit-based JSCD approach for VLCs. Simulation results show that the performance of the decoder can be significantly improved, while the computational complexity is only slightly increased by using our proposed schemes.     

Rate Optimization to Minimize Distortion for Source-Channel Coded H-BLAST with SIC Decoding

As joint source and channel coding schemes, layered transmission schemes for a successive refinable source (SRS) are recently studied over quasi-static fading channels. In this letter, we consider spatial layered transmission for a SRS with successive interference cancellation (SIC) decoder over quasistatic multi-input multi-output (MIMO) fading channels. We show that if the distortion function can be factorized, the minimum average distortion can be obtained by individual rate optimization for each layer when zero-forcing (ZF) SIC receiver is employed over Rayleigh fading channels.     

一种改进的自纠正最小和LDPC码的译码算法

低密度奇偶校验(LDPC)码是一类具有优良纠错能力的差错控制编码,可以逼近香农极限.目前LDPC码正在进入越来越多的工程应用中,高效的译码算法具有重要的价值.在研究已知的LDPC码译码算法的基础上,提出了一种改进的简化译码算法,称为加约束的自纠正最小和(CSCMS)算法,该算法的计算复杂度与最小和(MS)译码算法相当,性能却提升了0.2 dB左右,与其他几种改进的简化译码算法相比,性能提升约0.1 dB,并且译码的平均迭代次数也有所降低.     

An Iterative Extension of BLAST Decoding Algorithm for Layered Space-Time Signals

An Iterative Extension of BLAST Decoding Algorithm for Layered Space-Time Signals We propose an iterative extension of the Bell Laboratory Layered Space–Time (BLAST) algorithm and its variant VBLAST. A characteristic feature of the BLAST-type algorithm is that symbol decisions with low reliability are fed back to decode other symbols. Both performance analysis based on Gaussian approximation of residual interference and simulation results demonstrate that error propagation due to unreliable decision feedback can severely limit system performance. The extended algorithm exploits inherent signal diversity in BLAST to mitigate residual interference, thus overcoming the performance bottleneck due to error propagation. It yields an impressive performance gain over BLAST. In particular, the extension of BLAST with zero-forcing interference ing (EXT-ZF-BLAST) admits a simple QR implementation and exhibits excellent performance with low complexity.