共查询到19条相似文献,搜索用时 93 毫秒
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文章从单奇偶检验码的最大后验概率译码出发推导了LDPC码的消息传递机制。并基于此介绍了LDPC码的分层置信传播译码算法。然后结合工程实现给出了三种不同的缩短码实现方案,并通过仿真验证了三种缩短方案的有效性。最后在头部缩短方案的基础上搭建了基于FPGA的高速数传系统,中频环路上进行误码率性能测试表明头部缩短方案在复杂度和性能上有比较好的折中,误码率与理论值相差小于1.5d B。 相似文献
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多进制(Q-ary)LDPC码的编译码原理 总被引:2,自引:0,他引:2
多进制(Q-ary)LDPC码是将二进制LDPC码一般化到有限域GF(q),其校验矩阵元素不再是(0,1),而是集合(0,1,…,q-1),其译码仍然采用高效的信度传递迭代译码算法.本文主要阐述了多进制LDPC码的编译码原理,并介绍了一种可简化译码的傅立叶变换译码算法.通过将多进制LDPC码的性能与二进制LDPC码和RS码的性能进行比较,可以看出多进制LDPC码在磁存储系统、下一代ADSL系统以及深空通信方面将是取代RS码的强有力的候选,有极其重要的应用价值. 相似文献
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主要介绍了低密度奇偶校验码(LDPC)的基本概念及规则和非规则两种典型的LDPC码的结构,简要介绍了LDPC码的译码算法,在此基础上,引出两种非规则LDPC码的简化译码算法,仿真验证算法较大地降低了译码复杂度,并在高信噪比下性能损失较小. 相似文献
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本文研究了卷积LDPC码在瑞利衰落信道下的译码性能,给出了瑞利信道下,卷积LDPC码的译码算法,在同等条件下对比了卷积LDPC码在高斯信道和瑞利衰落信道下的译码性能。 相似文献
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本文在研究了LDPC码的基本译码算法的基础上,针对BP及其简化算法译码收敛慢的不足的缺点,提出了一种将TDMP算法和NMS算法相结合的TDMP-NMS算法作为WIMAX标准LDPC译码器的译码算法.该算法综合了TDMP算法译码收敛快和NMS算法在保证误码率性能的前提下校验节点处理简单的优点,最终实现了基于WIMAX标准的LDPC码译码器. 相似文献
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The problem of improving the performance of min-sum decoding of low-density parity-check(LDPC)codes is considered in this paper.Based on rain-sum algorithm,a novel modified min-sum decoding algorithm for LDPC codes is proposed.The proposed algorithm modifies the variable node message in the iteration process by averaging the new message and previous message if their signs are different.Compared with the standard min-sum algorithm,the modification is achieved with only a small increase in complexity,but significantly improves decoding performance for both regular and irregular LDPC codes.Simulation results show that the performance of our modified decoding algorithm is very close to that of the standard sum-produet algorithm for moderate length LDPC codes. 相似文献
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The simplicity of decoding is one of the most important characteristics of the low density parity check (LDPC) codes. Belief propagation (BP) decoding algorithm is a well‐known decoding algorithm for LDPC codes. Most LDPC codes with long lengths have short cycles in their Tanner graphs, which reduce the performance of the BP algorithm. In this paper, we present 2 methods to improve the BP decoding algorithm for LDPC codes. In these methods, the calculation of the variable nodes is controlled by using “multiplicative correction factor” and “additive correction factor.” These factors are obtained for 2 separate channels, namely additive white Gaussian noise (AWGN) and binary symmetric channel (BSC), as 2 functions of code and channel parameters. Moreover, we use the BP‐based method in the calculation of the check nodes, which reduces the required resources. Simulation results show the proposed algorithm has better performance and lower decoding error as compared to BP and similar methods like normalized‐BP and offset‐BP algorithms. 相似文献
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Tao Tian Jones C.R. Villasenor J.D. Wesel R.D. 《Communications, IEEE Transactions on》2004,52(8):1242-1247
This letter explains the effect of graph connectivity on error-floor performance of low-density parity-check (LDPC) codes under message-passing decoding. A new metric, called extrinsic message degree (EMD), measures cycle connectivity in bipartite graphs of LDPC codes. Using an easily computed estimate of EMD, we propose a Viterbi-like algorithm that selectively avoids small cycle clusters that are isolated from the rest of the graph. This algorithm is different from conventional girth conditioning by emphasizing the connectivity as well as the length of cycles. The algorithm yields codes with error floors that are orders of magnitude below those of random codes with very small degradation in capacity-approaching capability. 相似文献
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Loop distribution of Tanner graph affects the BER performance of low-density parity-check codes(LDPC) decoding.To count short cycles in the Tanner graph efficiently,a side by side recursion algorithm based on matrix computation was proposed.Firstly,5 basic graph structures were defined to realize recursive calculate in the implementation process.Compared with previous works,the algorithm provided many methods for counting the same length of cycles.The same result confirmed the correctness of the algorithm.The new algorithm could not only calculate the total number of cycles,but also gave the number each edge participating in fixed-length cycles.Its complexity was proportional to the product of D and square of N,where D was the average degree of variable nodes,and N denoted the code length.For LDPC codes,D was far less than N.For most of the LDPC codes,the calculation for numbers of cycle-length g、g+2、g+4 was only several seconds. 相似文献
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有限平面LDPC码是一类重要的有结构的LDPC码,在利用和积算法(SPA)等迭代译码方法进行译码时表现出卓越的纠错性能。众所周知,次优的迭代译码不是最大似然译码,因而如何对迭代译码的性能进行理论分析一直是LDPC码的核心问题之一。近几年来,Tanner图上的停止集(stopping set)和停止距离(stopping distance)由于其在迭代译码性能分析中的重要作用而引起人们的重视。该文通过分析有限平面LDPC码的停止集和停止距离,从理论上证明了有限平面LDPC码的最小停止集一定是最小重量码字的支撑,从而对有限平面LDPC码在迭代译码下的良好性能给出了理论解释。 相似文献