级联RS码改善Turbo码的性能

分析了Turbo码的错误平层和迭代译码特性,研究了Turbo码与RS码的级联系统(TC-RS级联码)。分析和模拟表明:TC-RS级联系统不仅明显降低了帧错率(FER)和误比特率(BER),而且能够减少译码迭代次数,译码时间复杂度也低于标准Turbo码。     

级联码译码在PC平台上的实现

对清华小卫星地面应用系统级联码译码的研制进行较详细的阐述，比较各种实现的途径，并详细介绍如何利用PC机方法来实现该级联码译码。分别从硬件和软件，数据接收和数据处理的不同角度对其进行介绍，并对卷积码的Viterbi译码，RS码的Berlekamp迭代译码算法以及数据的加扰解扰作了简要的介绍。     

一种级联的Turbo码系统

利用RS码和Turbo码级联,产生了一种级联的Turbo码系统。通过仿真,发现该系统具有较好的误帧率(FER),并且对AWGN信道中高信嗓比下的“平板效应”也有一定的抑制作用。同时,通过特定的动态终止算法,可以减少Tur-bo码译码的迭代次数,节省译码时间。     

级联码在遥测系统中的应用

遥测信道是一种典型的时变衰落信道,为弥补信道衰落对信息传输质量的影响,通常采用纠错编码的方法比单纯依靠加大系统功率裕量的方法更有意义。根据RS码的相关理论及编译码原理,结合遥测信道的特点,提出了RS码与卷积码级联的编译码方案,最后对该级联码的方案进行了软件仿真和硬件设计。实现结果表明级联码的增益要优于单纯的卷积码2 dB。     

基于级联码的差错控制系统的设计与实现

介绍了级联码编码与译码的设计和实现。该级联码由RS码、卷积码以及郑交织器构成。编码电路可用CPLD实现，译码采用AHA4210芯片完成，速度快。编译码的各种参数和过程由软件控制，非常灵活。通过加载不同的软件可以在同一硬件平台上实现多种的级联、RS码、卷积码或是卷交织器。在工程中有很高的实用价值。     

Woven卷积码及其迭代译码算法

本文在以卷积码为分量码的串行级联码的软输入软输出(SISO)算法的基础上，提出一种模块化的用于Woven卷积码迭代译码的对数SISO算法。计算机仿真表明该算法具有收敛速度快译码性能高的特点。     

RS码与LDPC码的联合迭代译码

针对RS码与LDPC码的串行级联结构,提出了一种基于自适应置信传播(ABP)的联合迭代译码方法.译码时,LDPC码置信传播译码器输出的软信息作为RS码ABP译码器的输入;经过一定迭代译码后,RS码译码器输出的软信息又作为LDPC译码器的输入.软输入软输出的RS译码器与LDPC译码器之间经过多次信息传递,译码性能有很大提高.码长中等的LDPC码采用这种级联方案,可以有效克服短环的影响,消除错误平层.仿真结果显示:AWGN信道下这种基于ABP的RS码与LDPC码的联合迭代译码方案可以获得约0.8 dB的增益.     

级联纠错编码DS/BPSK系统性能分析与仿真

为了研究级联编码对DS/BPSK系统性能的影响,设计了一种基于RS与卷积码级联编码的DS/BPSK系统,分析了该级联编码直扩系统的性能,仿真了在纠错编码参数发生改变时的系统性能。仿真结果表明,级联编码的DS/BPSK系统性能比单码编码的DS/BPSK系统性能要好。在RS码参数保持不变时,降低卷积码的码率,采用软判决方式译码以及多比特软判决,能有效提升系统性能;同时,交织在一定程度上能改善系统的性能。     

WiMAX系统中RS-CC级联码的算法研究

保证在高速数据传输的情况下提供可靠的服务质量,信道编码是解决此问题的有效途径。文章重点研究了WiMAX系统中RS-CC级联码的编译码技术,尤其是RS编译码和卷积码的Viterbi算法。     

非二进制Turbo级联码的性能分析

该文在分析了非二进制Turbo码的译码算法的基础上,提出了非二进制Turbo码和具有良好纠突发错误的RS码级联的非二进制Turbo级联码系统模型。该系统采用缩短的RS码(204, 188)作为外码,非二进制Turbo码作为内码的串行级联方式,内码和外码之间用深度为12的交织器隔开,译码时, 非二进制Turbo码分别采用Symbol-by-Symbol Log-MAP和SOVA算法。仿真结果显示,与二进制Turbo级联码系统相比,该系统具有误码率低,延时时间短,频带利用率高等优点。     

Improved FEC Code Based on Concatenated Code for Optical Transmission Systems

The improved three novel schemes of the super forward error correction(super-FEC) concatenated codes are proposed after the development trend of long-haul optical transmission systems and the defects of the existing FEC codes have been analyzed. The performance simulation of the Reed-Solomon(RS)+Bose-Chaudhuri-Hocguenghem(BCH) inner-outer serial concatenated code is implemented and the conceptions of encoding/decoding the parallel-concatenated code are presented. Furthermore, the simulation results for the RS(255,239)+RS(255,239) code and the RS(255,239)+RS(255,223) code show that the two consecutive concatenated codes are a superior coding scheme with such advantages as the better error correction, moderate redundancy and easy realization compared to the classic RS(255,239) code and other codes, and their signal to noise ratio gains are respectively 2～3dB more than that of the RS(255,239)code at the bit error rate of 1×10 -13 . Finally, the frame structure of the novel consecutive concatenated code is arranged to lay a firm foundation in designing its hardware.     

RS级联编码在超短波通信与卫星通信信道的仿真分析

超短波波段数据通信与卫星通信已被广泛应用。在这些信道中都存在较强的多径衰落,并且为克服两个波段中的多种干扰,纠正随机错误和突发错误,RS编码被普遍选为信道编码方案。RS码是线性分组码中纠突发错误能力最强,效率最高的编码,Turbo码是可以接近香农限的编码方案。文章提出RS编码与Turbo码的级联码编码方案和解码算法,适当选择参数,并通过仿真验证了方案的正确性与可行性。     

低时延RS-CC级联码的设计与实现

为提高手持无线电台的纠错和时延特性,考虑设计一种短码长RS-CC级联码.通过对Reed-Solomon码缩短和截断以及对卷积码删余,提出了一种低时延的级联码设计方案,并进行性能分析和软硬件实现.结果表明,在高斯信道下,当Eb/No达到4.2 dB时,能够实现10-4的误码率性能.设计的RS-CC级联码码长较短,编解码固有时延低,译码速度提升30％,适合低时延应用.     

Reed-Solomon codes for correcting phased error bursts

A code structure is introduced that represents a Reed-Solomon (RS) code in two-dimensional format. Based on this structure, a novel approach to multiple error burst correction using RS codes is proposed. For a model of phased error bursts, where each burst can affect one of the columns in a two-dimensional transmitted word, it is shown that the bursts can be corrected using a known multisequence shift-register synthesis algorithm. It is further shown that the resulting codes posses nearly optimal burst correction capability, under certain probability of decoding failure. Finally, low-complexity systematic encoding and syndrome computation algorithms for these codes are discussed. The proposed scheme may also find use in decoding of different coding schemes based on RS codes, such as product or concatenated codes.     

一种基于增强奇偶校验码级联极化码的新型编译码方法

极化码作为一种纠错码,具有较好的编译码性能,已成为5G短码控制信道的标准编码方案。但在码长较短时,其性能不够优异。提出一种基于增强奇偶校验码级联极化码的新型编译码方法,在原有的奇偶校验位后设立增强校验位,对校验方程中信道可靠度较低的信息位进行双重校验,辅助奇偶校验码在译码过程中对路径进行修剪,以此提高路径选择的可靠性。仿真结果表明,在相同信道、相同码率码长下,本文提出的新型编译码方法比循环冗余校验(cyclic redundancy check,CRC)码级联极化码、奇偶校验(parity check,PC)码级联极化码误码性能更优异。在高斯信道下,当码长为128、码率为1/2、误码率为10-3时,本文提出的基于增强PC码级联的极化码比PC码级联的极化码获得了约0.3 dB增益,与CRC辅助的极化码相比获得了约0.4 dB增益。     

High rate concatenated coding systems using bandwidth efficienttrellis inner codes

High-rate concatenated coding systems with bandwidth-efficient trellis inner codes and Reed-Solomon (RS) outer codes are investigated for application in high-speed satellite communication systems. Two concatenated coding schemes are proposed. In one the inner code is decoded with soft-decision Viterbi decoding, and the outer RS code performs error-correction-only decoding (decoding without side information). In the other the inner code is decoded with a modified Viterbi algorithm, which produces reliability information along with the decoded output. In this algorithm, path metrics are used to estimate the entire information sequence, whereas branch metrics are used to provide reliability information on the decoded sequence. This information is used to erase unreliable bits in the decoded output. An errors-and-erasures RS decoder is then used for the outer code. The two schemes have been proposed for high-speed data communication on NASA satellite channels. The rates considered are at least double those used in current NASA systems, and the results indicate that high system reliability can still be achieved     

LDPC Decoding by Failed Check Nodes for Serial Concatenated Code

The use of serial concatenated codes is an effective technique for alleviating the error floor phenomenon of low‐density parity‐check (LDPC) codes. An enhanced sum–product algorithm (SPA) for LDPC codes, which is suitable for serial concatenated codes, is proposed in this paper. The proposed algorithm minimizes the number of errors by using the failed check nodes (FCNs) in LDPC decoding. Hence, the error‐correcting capability of the serial concatenated code can be improved. The number of FCNs is simply obtained by the syndrome test, which is performed during the SPA. Hence, the decoding procedure of the proposed algorithm is similar to that of the conventional algorithm. The error performance of the proposed algorithm is analyzed and compared with that of the conventional algorithm. As a result, a gain of 1.4 dB can be obtained by the proposed algorithm at a bit error rate of 10^?8. In addition, the error performance of the proposed algorithm with just 30 iterations is shown to be superior to that of the conventional algorithm with 100 iterations.     

乘积码迭代译码算法研究

介绍了在分组码的软输入软输出译码基础上以扩展BCH码为子码的乘积码的迭代译码算法,提出了在高带宽利用率调制方式下的算法应用方式,并给出了仿真结果。最后与传统的并联卷级码代译码方案比较,发现在高编码效率时,乘积码迭代译码方案有着较好的应用性。     

RS-Turbo级联码的性能仿真及其在图像传输中的应用

RS码是一种纠突发错误能力很强的信道编码方式,Turbo码是一种巧妙的将卷积码和随机交织器结合在一起,同时采用软输出并通过不断迭代的方法译码来逼近最大似然编码的一种新的纠错能力很强的信道编码方式;本文分析了两种编码方式并研究了将二者级联后RS-Turbo的性能,给出了将其级联码在图像传输中的应用.