基于CNN扰动的极化码译码算法

针对中短码长下串行抵消(SC)算法性能较差,且串行抵消列表(SCL)算法复杂度较高等问题,根据译码纠错空间理论,该文提出了一种基于卷积神经网络(CNN)扰动的极化码译码算法.对SC译码失败的接收序列,通过CNN产生相应的扰动噪声,并将该扰动噪声添加到接收信号中,然后根据重新计算的似然信息进行译码.仿真结果表明:与SC译码算法相比,所提出的算法约有0.6 dB的增益,与SCL(L=16)译码算法相比,该算法约有0.1 dB的提升,且平均复杂度更低.     

基于CNN扰动的极化码译码算法

针对中短码长下串行抵消(SC)算法性能较差,且串行抵消列表(SCL)算法复杂度较高等问题,根据译码纠错空间理论,该文提出了一种基于卷积神经网络(CNN)扰动的极化码译码算法。对SC译码失败的接收序列,通过CNN产生相应的扰动噪声,并将该扰动噪声添加到接收信号中,然后根据重新计算的似然信息进行译码。仿真结果表明:与SC译码算法相比,所提出的算法约有0.6 dB的增益,与SCL(L=16)译码算法相比,该算法约有0.1 dB的提升,且平均复杂度更低。     

动态扰动辅助的串行抵消双比特翻转Polar译码算法

针对串行抵消翻转译码算法（Successive Cancellation Flip,SCF）受限于单比特翻转而性能提升有限问题,提出了一种双比特翻转译码算法（Successive Cancellation Flip with 2 Bits,SCF2）。针对SCP算法扰动方差初始值固定的问题,设计了一种扰动方差可随码长和码率变化的改进SCP算法。在此基础上,结合翻转和扰动机制,提出了一种动态扰动辅助的串行抵消双比特翻转（Dynamic Perturbation-Aided SCF2,DPA-SCF2）译码算法,并对其译码复杂度和性能进行了分析。仿真结果显示,相比于列表长度为4的循环冗余校验辅助串行抵消列表（Cyclic Redundancy Check Aided Successive Cancellation List,CA-SCL）译码算法,所提算法最大可获得约0.5 dB的性能增益。     

基于分布式奇偶校验码的低复杂度极化码SCLF译码算法

针对极化码串行抵消列表比特翻转(Successive Cancellation List Bit-Flip, SCLF)译码算法复杂度较高的问题,提出一种基于分布式奇偶校验码的低复杂度极化码SCLF译码(SCLF Decoding Algorithm for Low-Complexity Polar Codes Based on Distributed Parity Check Codes, DPC-SCLF)算法。与仅采用循环冗余校验(Cyclic Redundancy Check, CRC)码校验的SCLF译码算法不同,该算法首先利用极化信道偏序关系构造关键集,然后采用分布式奇偶校验(Parity Check, PC)码与CRC码结合的方式对错误比特进行检验、识别和翻转,提高了翻转精度,减少了重译码次数。此外,在译码时利用路径剪枝操作,提高了正确路径的竞争力,改善了误码性能,且利用提前终止译码进程操作,减少了译码比特数。仿真结果表明,与D-Post-SCLF译码算法和RCS-SCLF译码算法相比,所提出算法具有更低的译码复杂度且在中高信噪比下具有更好的误码性能。     

一种基于错误集的极化码改进SCL译码算法

针对极化码在中短码长时纠错性能的不足,提出了一种基于错误集的极化码改进串行抵消列表(Successive Cancellation List of Polar Codes Based on Error Set,ES-SCL)译码算法。该算法首先根据极化码的信道特性构造错误集,在极化码编码时根据错误集中的元素设置奇偶校验(Parity Check,PC)位,其余位置则放置信息比特和冻结比特,译码器在译码PC位时,每条路径通过校验函数得到PC位的比特估计,不执行路径分裂和剪枝,其余位置则执行SCL译码。仿真结果表明,在加性高斯白噪声信道下,当码长为512,码率为0.5,误块率为10-5,最大译码列表数为8时,相较于PC-PSCL译码算法以及CA-SCL译码算法,所提出的ES-SCL译码算法获得了约0.18和0.15dB的增益;当码长为256,码率为0.5,误码率为10-5,最大译码列表数为8时,相较于CA-SCL,PC-PSCL译码算法,获得了约0.3和0.35dB的增益;此外,采用部分比特分裂译码的ES-SCL译码算法可以在误块率与PC-PSCL译码算法几乎相同的情况下,减少约50%的排序次数,具有更低的译码复杂度。     

一种5G系统自适应快速SCL极化码译码算法

针对5G系统控制信道的极化码译码性能问题,基于快速串行抵消列表(Fast Successive Cancellation List,FSCL)译码算法,提出了一种自适应快速串行抵消列表(Adaptive FSCL,AD-FSCL)译码算法.该算法能够降低译码复杂度,设置列表初始值,对极化码的4种特殊节点进行相应的快速译...     

基于分段循环冗余校验的极化码自适应连续取消列表译码算法

针对极化码连续取消列表(SCL)译码算法为获取较好性能而采用较多的保留路径数,导致译码复杂度较高的缺点,自适应SCL译码算法虽然在高信噪比下降低了一定的计算量,却带来了较高的译码延时。根据极化码的顺序译码结构,该文提出了一种分段循环冗余校验(CRC)与自适应选择保留路径数量相结合的SCL译码算法。仿真结果表明,与传统CRC辅助SCL译码算法、自适应SCL译码算法相比,该算法在码率R=0.5时,低信噪比下(–1 dB)复杂度降低了约21.6%,在高信噪比下(3 dB)复杂度降低了约64%,同时获得较好的译码性能。     

系统极化码的低时延CA-SCL算法研究

文章为了降低极化码的串行抵消列表(Successive Cancellation List,SCL)算法的译码时延,利用简化串行抵消(Simplified SC,SSC)算法思想,设计实现了系统极化码(system polar code,SPC)低复杂度(low complexity)的循环冗余校验辅助串行抵消列表(CRC-Aided SCL,CA-SCL)译码,简称为SPC-LC-CA-SCL算法。仿真结果表明:极化码(1024,512)中"Rate-1"节点并行处理的门限值(Threshold Value)设为64时,SPC-LC-CA-SCL和SPC-CA-SCL算法性能一致,时延减少了6.35%。"Rate-1"节点并行处理的门限值设为32,16时,时延分别减少了17.78%和24.13%,性能则降低了0.4dB和0.5dB。     

一种基于奇偶校验码级联极化码的低复杂度译码算法

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.作为一种新型级联极化码,奇偶校验码与极化码的级联方案提高了有限码长的性能,但是其译码算法有着较高的复杂度.该文针对这一问题,提出一种基于奇偶校验码级联极化码的串行抵消局部列表译码(PC-PSCL)算法,该算...     

一种基于新度量准则的极化码SCLF译码算法

为了解决串行抵消(Successive Cancellation,SC)译码算法在中短码长情况下译码性能不佳的问题,在SC译码算法的基础上增加路径列表和比特翻转方法得到一种改进的串行抵消列表翻转(Successive Cancellation List Flip,SCLF)译码算法.该算法利用比特翻转构建最不可靠的信息位集合,称为翻转集合(Flipping Set,FS),同时提出一种新的度量法则来缩小FS的范围、提高FS的准确率.仿真结果表明,随着信噪比的增大,所提出的SCLF译码算法误块率(Block Error Rate,BLER)有较大提升,当BLER为10-3时,SCLF(码长N=256,列表大小L=8)译码算法的增益比SC(N=256)译码算法提升了 0.55 dB;当BLER为10-4时,SCLF(N=256,L=8)译码算法的增益比CA-SCL(N=256,L=8)译码算法提升了 0.22 dB;当BLER为10-5时,SCLF(N=256,L=16)译码算法的增益比CA-SCL(N=256,L=16)译码算法提升了 0.17 dB.     

光纤通信中降低LDPC码译码复杂度的方法

伪循环(QC)低密度奇偶校验(LDPC)码可以给光纤通信系统带来更高的编码增益,但译码过程需要的对数似然比(LLR)的计算很复杂.为了降低LDPC译码器硬件设计的复杂度,文章提出一种光纤信道下简化的LLR的计算方法.仿真结果表明,该计算方法与原计算方法相比仅有0.05 dB的译码性能损失.     

An improved AS-SCLF decoding algorithm of polar codes based on the assigned set

An improved successive cancellation list bit-flip based on assigned set (AS-SCLF) decoding algorithm is proposed to solve the problems that the successive decoding of the successive cancellation (SC) decoder has error propagation and the path extension of the successive cancellation list (SCL) decoder has the decision errors in the traditional cyclic redundancy check aided successive cancellation list (CA-SCL) decoding algorithm. The proposed algorithm constructs the AS firstly. The construction criterion is to use the Gaussian approximation principle to estimate the reliabilities of the polar subchannel and the error probabilities of the bits under SC decoding, and the normalized beliefs of the bits in actual decoding are obtained through the path metric under CA-SCL decoding, thus the error bits containing the SC state are identified and sorted in ascending order of the reliability. Then the SCLF decoding is performed. When the CA-SCL decoding fails for the first time, the decision results on the path of the SC state in the AS are exchanged. The simulation results show that compared with the CA-SCL decoding algorithm, the SCLF decoding algorithm based on the critical set and the decision post-processing decoding algorithm, the improved AS-SCLF decoding algorithm can improve the gain of about 0.29 dB, 0.22 dB and 0.1 dB respectively at the block error rate (BLER) of 10-4 and reduce the number of decoding at the low signal-to-noise ratio (SNR), thus the computational complexity is also reduced.     

Improved LDPC-based short-range frequency-hopping wireless communication system

In short-range wireless communication system(SWCS),the complex scenarios make its transmission face the diverse interference,and lower hardware resource leads to its limited anti-interference capability.To achieve the reliable transmission,a frequency-hopping-based SWCS (FH-SWCS)with improved LDPC (I-LDPC) code was constructed.In FH-SWCS,a low-complexity check-sum updating(LCU)algorithm was proposed to reduce the amount of computation.LCU-based multi-threshold bit flipping (LCU-MTBF) algorithm was given to increase the reliability of bit-flipping, improving decoding performance and reduce the complexity of decoding.The simulation results demonstrate that LCU is suitable for multiple hard decisions decoding algorithm,and it can reduce the computational complexity of original decoding algorithm without affecting its performance.When BER is 10^?5,and iterations number is 5,0.15dB performance gain can be achieved,and the number of additions algorithm can be reduced about 40% in LCU-MTBF.In FH-SWCS with I-LDPC,when BER is 10^?4,and SNR is 15dB,the performance gain about 7dB can be achieved to improve the anti-interference of the system effectively.     

Research on encoding and decoding of non-binary polar codes over GF(2m)

Binary Polar Codes (BPCs) have advantages of high-efficiency and capacity-achieving but suffer from large latency due to the Successive-Cancellation List (SCL) decoding. Non-Binary Polar Codes (NBPCs) have been investigated to obtain the performance gains and reduce latency under the implementation of parallel architectures for multi-bit decoding. However, most of the existing works only focus on the Reed-Solomon matrix-based NBPCs and the probability domain-based non-binary polar decoding, which lack flexible structure and have a large computation amount in the decoding process, while little attention has been paid to general non-binary kernel-based NBPCs and Log-Likelihood Ratio (LLR) based decoding methods. In this paper, we consider a scheme of NBPCs with a general structure over GF(2^m). Specifically, we pursue a detailed Monte-Carlo simulation implementation to determine the construction for proposed NBPCs. For non-binary polar decoding, an SCL decoding based on LLRs is proposed for NBPCs, which can be implemented with non-binary kernels of arbitrary size. Moreover, we propose a Perfect Polarization-Based SCL (PPB-SCL) algorithm based on LLRs to reduce decoding complexity by deriving a new update function of path metric for NBPCs and eliminating the path splitting process at perfect polarized (i.e., highly reliable) positions. Simulation results show that the bit error rate of the proposed NBPCs significantly outperforms that of BPCs. In addition, the proposed PPB-SCL decoding obtains about a 40% complexity reduction of SCL decoding for NBPCs.     

Mixed-Q linear space-time codes

A new modulation method for linear space-time codes is proposed based on using constellations of different sizes for different symbols. It is shown that the proposed method significantly reduces the complexity of the sphere decoding algorithm. The complexity reduction is more pronounced in high-rate codes, where each code matrix carries a large number of symbols. We also show that the choice of constellation size provides a tradeoff between performance and complexity. Using this, some guidelines for choosing constellation size are presented. As one introduces more constellation disparity in the code, the complexity is further reduced, while the performance loss grows. Typically, a complexity reduction of one to two orders of magnitude can be achieved at the expense of about 3 dB coding gain. We suggest a simple modification in our design to reduce this loss to about 2 dB.     

基于PD-CNN的Polar码译码算法

针对传统Polar码译码算法在相关噪声信道下性能严重下降的问题,提出了一种基于前置预判-卷积神经网络（Prior Decision-Convolutional Neural Networks,PD-CNN）的译码算法。通过前置预判深度优化CNN,使其准确地估计信道噪声并使残余噪声尽可能遵循高斯分布,再根据残余噪声分布统计更新出可靠的似然比信息。分析了不同译码算法对不同码率Polar码在不同噪声相关强度下的译码性能,并与本文所提出的译码算法进行对比。仿真结果表明:在相关噪声信道下,当误码率为10-5时,本文所提出的译码算法与标准置信度传播算法相比可获得约2.5 Bd的增益。此外,在高信噪比时,与置信度传播-卷积神经网络算法相比,本文提出的译码算法具有相同的性能,但复杂度更低,译码延迟最大可减少42%。