交织编码在数字集群系统语音业务信道中的性能研究

该文对于交织编码在数字集群系统语音业务信道中的应用做了详细的研究,结合CRC和RCPC编码以及ACELP语音编码,讨论了交织编码对于不同QOS语音数据的纠错性能影响,并通过计算机仿真给出了不同条件下有交织与无交织编码时,系统纠错性能曲线,为数字集群系统的实际应用提供了重要的理论依据。     

交织编码在TETRA数字集群系统语音业务信道中的性能研究

本文详细地研究了交织编码在数字集群系统语音业务信道中的应用，结合CRC和RCPC编码以及ACELP语音编码，讨论了交织编码对于不同QoS语音数据的纠错性能影响，通过计算机仿真给出了在不同条件下有交织与无交织编码的系统纠错性能曲线，为数字集九系统的实际应用提供了重要的理论依据。     

TETRA数字集群移动通信系统信道编码机制

文章以TETRA（陆上集群无线电）数字集群移动通信系统的逻辑信道类别为主线,介绍了系统的信道编码技术,并着重强调了数据业务信道编码技术的重要性和编码机制,对于TETRA数字集群移动通信系统的研发运用具有重要的实践指导意义。     

一种综合源编码和信道编码的图像编码方案

提出了一新的综合源编码和信道编码的图像编码传输方案，对子波变换后各个子带采用基于统计特性的变系数定长（VCFL）编码后选择不同码率的RCPC（码率兼容的删除卷积码，Rate Compatible Punctured Convolutional code)信道编码以提供不同程度的差错保护（UEP）并进行传输。在给定传输的总比特数的情况下，通过一种优化算法使方案的总体失真最小。模拟结果表明新方案压缩比高，在较高的传输误码率情况下，表现出良好的抗误码能力。     

无线ATM系统前向纠错方案的改进

前向纠错（FEC）主要用于提高信道的传输性能,在ATM信元头中有CRC纠错方案HEC,但是主要是针对光纤等优良信道,对于干扰严重的无线信道,应有更有力的纠错方案。本文是在信道编码方案确定的条件下,提出进一步提高纠错能力、降低信无丢失率的方法。     

基于LDPCA的分布式视频编码实现及应用

分布式视频编码技术（Distributed Video Coding）是一种新颖的联合信源信道编码技术,在视频传输的差错控制、压缩、纠错上表现突出。文中利用LDPCA实现分布式编码,在实现较高压缩比的视频压缩方案的同时,实现了视频数据的自我纠错,增强了视频的抗噪能力和鲁棒性,能有效去除各种数字污染和噪声,保证数据完整性和唯一性,扩展了分布式编码技术的应用。     

一种抗误码能力强的无线信道图像传输方案

本文提出一种新的综合源编码和信道编码的无线信道图像传输方案，对子波变换后各个子带采用基于统计特性的变系数定长（VCFL）编码，数据经过Reed-Solomon编码后选择不同码率的码率兼容删除卷积码（RCPC）编码以提供不同程度的差错保护（UEP），最后数据经交织后传输。在给定传输的总比特数的情况下，通过优化算法使总体失真最小。模拟结果表明新方案在无线衰落信道上表现出良好的性能。     

一种基于DSP的数字集群信道编码实现方案

该文给出了一种基于DSP的数字集群信道编码实现方案,并从硬件平台和软件流程两个方面详尽地介绍了模块内部和模块间的各种接口,为数字集群系统的整体实现迈出了关键性的一步。     

数字集群技术及市场前景

集群通信系统是专用于调度的通信系统。它从一对一对讲机的形式、同频单工组网形式、异频单（双）工组网形式到单信道一呼百应以及进一步带选呼的系统,发展到多信道自动拨号系统。最早进入我国的集群通信系统是模拟集群通信系统。其信令是采用数字方式的,话音传输采用模拟方式,这是模拟集群系统与数字集群系统的最大区别。现在主流的数字集群系统采用的是TDMA的系统,另外在信道编码上采用了先进     

卷积码Viterbi译码器的硬件实现

第三代移动通信系统标准中普遍采用卷积码和Turbo码作为信道编码方案。本文首先阐述了维特比译码算法,然后论述了（2,1,3）卷积码编码电路和维特比译码的单片机实现方案。最后把维特比算法与交织方案相结合,统计结果表明纠错性能有较大改善。     

数字视频广播中删除卷积码的优化译码算法

介绍DVB中删除卷积码的编译码方法,同时提出了一种优化译码算法.该算法增强了纠错能力,提高了译码精度,加强了通信系统的可靠性和有效性,尤其对DVB中可变码率的删除卷积码的译码具有很好的实用性.     

New rate-compatible punctured convolutional codes for Viterbidecoding

New good rate-P/(P+δ) rate-compatible punctured convolutional (RCPC) codes for 2⩽P⩽7 and 1⩽δ⩽(n-1)P were found and tabulated, These codes have been determined by iterative search based upon a criterion of maximizing the free distance and were generated by periodically puncturing their rate-1/n mother codes of memory 2⩽M⩽6 and n=2. These codes are expected to find their applications in unequal error protection schemes employing Viterbi decoding     

小波编码图像联合信源信道解码算法的研究

为提高图像在噪声信道中传输的可靠性,该文提出了一种图像联合信源信道解码方案。信源图像首先经离散小波变换,压缩编码。编码数据经RCPC(率兼容删余卷积码)信道编码保护,通过噪声信道传输。在接收端的改进的APRI-SOVA (先验信息软输出维特比算法)在信道解码时,不仅利用了信道输出的软判决,而且进一步利用了信源解码器提供的当前解码的比特的可靠性信息。仿真结果显示,有效利用信源数据中遗留的相关性,能够实现图像解码质量的提高。     

卷积码维特比译码算法最佳反馈深度研究

卷积码可以用维特比算法作为译码算法,由于维特比译码器复杂度随着反馈深度的增长成指数倍增长,因而译码反馈深度对译码器的复杂度影响很大甚至可能无法实用,目前有些文献中仅给出了反馈深度的大致范围,但在硬件实现和性能仿真时无法确定一个具体的数值。通过在OFDM系统中运用卷积编码和维特比译码仿真分析发现,维特比译码器反馈深度为卷积码编码器存贮长度的5倍时,既可达到性能和硬件复杂度的良好折衷,又便于实际应用。     

1000 BASE-T收发器中的Viterbi译码算法研究

采用4维8状态网格编码和Viterbi译码相结合的方法，理论上可以获得6dB的编码增益，用于补偿采用PAM-5编码所带来的噪声容限损失。文章给出了针对4维8状态网格编码的Viterbi译码算法的译码过程，并就译码深度、量化精度和溢出处理方法对译码器性能的影响进行了算法仿真，确定出适合1000 BASE-T收发器应用的译码器参数。     

Fast adaptive arithmetic code for large alphabet sources with asymmetrical distributions

We address the problem of constructing an adaptive arithmetic code in the case where the source alphabet is large and there are lots of different symbols with equal counts of occurrence. For an alphabet of N symbols and r distinct symbol weights we describe a code for which the number of operations needed for encoding and decoding is equal to clogr+c/sub 1/ instead of clogN+c/sub 2/ as in previous arithmetic codes, c, c/sub 1/, c/sub 2/ are constants. When r is small relative to N-which is the case for most practical coding problems on large alphabets-the encoding and decoding speed of the suggested code will be substantially greater than with known methods.     

Markov model aided decoding for image transmission usingsoft-decision-feedback

Soft-decision-feedback MAP decoders are developed for joint source/channel decoding (JSCD) which uses the residual redundancy in two-dimensional sources. The source redundancy is described by a second order Markov model which is made available to the receiver for row-by-row decoding, wherein the output for one row is used to aid the decoding of the next row. Performance can be improved by generalizing so as to increase the vertical depth of the decoder. This is called sheet decoding, and entails generalizing trellis decoding of one-dimensional data to trellis decoding of two-dimensional data (2-D). The proposed soft-decision-feedback sheet decoder is based on the Bahl algorithm, and it is compared to a hard-decision-feedback sheet decoder which is based on the Viterbi algorithm. The method is applied to 3-bit DPCM picture transmission over a binary symmetric channel, and it is found that the soft-decision-feedback decoder with vertical depth V performs approximately as well as the hard-decision-feedback decoder with vertical depth V+1. Because the computational requirement of the decoders depends exponentially on the vertical depth, the soft-decision-feedbark decoder offers significant reduction in complexity. For standard monochrome Lena, at a channel bit error rate of 0.05, the V=1 and V=2 soft-decision-feedback decoder JSCD gains in RSNR are 5.0 and 6.3 dB, respectively.     

Generalised rate N/(N+1) codes

A generalised construction of rate M(N+1) run-length limited codes is presented. The (d, k, l, r) constraints are (0, N/4+1, N/8: N/8). Encoding and decoding based on the use of multiple pivot bits are described. The encoding and decoding are systematic enough to allow the writing of software to generate efficient logic equations for different N. The logic equations can be further minimised using an automatic synthesis tool     

Rate-compatible punctured convolutional codes (RCPC codes) andtheir applications

The concept of punctured convolutional codes is extended by punctuating a low-rate 1/N code periodically with period P to obtain a family of codes with rate P/(P+l), where l can be varied between 1 and (N-1)P. A rate-compatibility restriction on the puncturing tables ensures that all code bits of high rate codes are used by the lower-rate codes. This allows transmission of incremental redundancy in ARQ/FEC (automatic repeat request/forward error correction) schemes and continuous rate variation to change from low to high error protection within a data frame. Families of RCPC codes with rates between 8/9 and 1/4 are given for memories M from 3 to 6 (8 to 64 trellis states) together with the relevant distance spectra. These codes are almost as good as the best known general convolutional codes of the respective rates. It is shown that the same Viterbi decoder can be used for all RCPC codes of the same M. the application of RCPC codes to hybrid ARQ/FEC schemes is discussed for Gaussian and Rayleigh fading channels using channel-state information to optimise throughput     

Improving RCPC Codes in Rate-Adaptive Optical Wireless Communications Systems

In this paper, we analyse the performance of rate-compatible punctured convolutional (RCPC) codes for wireless optical communications systems. For these environments, a novel hybrid RCPC coding scheme with a modified puncturing matrix is proposed based on the insertion of variable silence periods. This transmission technique achieves better bit-error rate results than conventional RCPC and convolutional coding schemes, in agreement to the obtained increase in the peak-to-average optical power ratio.