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The error correcting performance of the parallel concatenation of two convolutional codes is very promising. Inspired from this construction which is near the Shannon limit error correction performance, we consider a further development of concatenated codes. In this construction systematic convolutional codes and rate 1/2 systematic block codes are linked together such that only the systematic part of the convolutional codes is encoded with the block encoders. The bits of each information vector of the convolutional codes are scrambled by a given interleaving before entering to the block encoders. Then, differently from the Turbo codes, in which information symbols and the redundancy from the constituent codes are transmitted [1], we transmit only the redundancy from the convolutional and block codes. We call this construction convolutional coupled codes and code coupling is the new scheme of code concatenation. The structural properties of the generator matrix of the convolutional coupled code is investigated. It's minimum distance is lower and upper bounded and we introduce the term of the effective free distance. Simulation results will show, that convolutional coupled codes have the potential of being a realistic alternative to Turbo codes. 相似文献
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Gluesing-Luerssen H. Schneider G. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2008,54(4):1536-1550
The adjacency matrix associated with a convolutional code collects in a detailed manner information about the weight distribution of the code. A MacWilliams identity conjecture, stating that the adjacency matrix of a code fully determines the adjacency matrix of the dual code, will be formulated, and an explicit formula for the transformation will be stated. The formula involves the MacWilliams matrix known from complete weight enumerators of block codes. The conjecture will be proven for the class of convolutional codes where either the code itself or its dual does not have Forney indices bigger than one. For the general case, the conjecture is backed up by many examples, and a weaker version will be established. 相似文献
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In this article, we introduce a new class of product codes based on convolutional codes, called convolutional product codes. The structure of product codes enables parallel decoding, which can significantly increase decoder speed in practice. The use of convolutional codes in a product code setting makes it possible to use the vast knowledge base for convolutional codes as well as their flexibility in fast parallel decoders. Just as in turbo codes, interleaving turns out to be critical for the performance of convolutional product codes. The practical decoding advantages over serially‐concatenated convolutional codes are emphasized. 相似文献
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The classical Viterbi decoder recursively finds the trellis path (code word) closest to the received data. Given the received data, the syndrome decoder first forms a syndrome, instead. A recursive algorithm like Viterbi's is used to determine the noise sequence of minimum Hamming weight that can be a possible cause of this syndrome. Given the estimate of the noise sequence, one derives an estimate of the original data sequence. While the bit error probability of the syndrome decoder is no different from that of the classical Viterbi decoder, the syndrome decoder can be implemented using a read only memory (ROM), thus obtaining a considerable saving in hardware. 相似文献
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Chung-Hsuan Wang Mao-Ching Chiu Chi-chao Chao 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2010,56(1):296-315
In this paper, convolutional codes are studied for unequal error protection (UEP) from an algebraic theoretical viewpoint. We first show that for every convolutional code there exists at least one optimal generator matrix with respect to UEP. The UEP optimality of convolutional encoders is then combined with several algebraic properties, e.g., systematic, basic, canonical, and minimal, to establish the fundamentals of convolutional codes for UEP. In addition, a generic lower bound on the length of a UEP convolutional code is proposed. Good UEP codes with their lengths equal to the derived lower bound are obtained by computer search. 相似文献
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It is shown that a convolutional code can be decoded with a sliding-block decoder, a time-invariant nonlinear digital filter with finite memory and delay. If the memory and delay are small, then the sliding-block decoder can be implemented as a table lookup procedure in ROM, resulting in a low cost, high speed, and high reliability decoder. 相似文献
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In practical applications, some coded symbols are unequally punctured for rate matching of terminated convolutional codes. In this letter, performance upper bounds are proposed for a terminated convolutional code punctured with an arbitrary pattern. To obtain the upper bounds, a weight enumerator is defined to represent the relation between the Hamming weight of the coded outputs and that of the selected input information bits. A method is presented to compute the weight enumerator based on a modified trellis diagram. Simulation and numerical analysis show that the proposed bounds are tight to the performance of terminated convolutional codes. 相似文献
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LDPC卷积码的快速收敛译码 总被引:2,自引:2,他引:0
采用串行消息传递策略,文中提出了LDPC卷积码的一种改进的流水线式译码器.分析和仿真结果均表明改进的译码器在不增加单个处理器计算复杂度的前提下,仅通过改变消息传递方式就能够大大加速译码收敛速率,与原译码器相比大约可以节省一半的处理器. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(6):2267-2270
From a linear block code B over the Galois ring GR(4, m) with a k times n generator matrix and minimum Hamming distance d, a rate-k/n convolutional code over the ring Z4 with squared Euclidean free distance at least 2d and a nonrecursive encoder with memory at most m - 1 is constructed. When the generator matrix of B is systematic, the convolutional encoder is systematic, basic, noncatastrophic and minimal. Long codes constructed in this manner are shown to satisfy a Gilbert-Varshnmov bound. 相似文献
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Wei Zhang Lentmaier M. Zigangirov K.Sh. Costello D.J. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2010,56(1):316-331
We present a new class of iteratively decodable turbo-like codes, called braided convolutional codes. Constructions and encoding procedures for tightly and sparsely braided convolutional codes are introduced. Sparsely braided codes exhibit good convergence behavior with iterative decoding, and a statistical analysis using Markov permutors shows that the free distance of these codes grows linearly with constraint length, i.e., they are asymptotically good. 相似文献
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A recursive procedure is derived for decoding of rateR = 1/n binary convolutional codes which minimizes the probability of the individual decoding decisions for each information bit, subject to the constraint that the decoding delay be limited to Δ branches. This new decoding algorithm is similar to, but somewhat more complex than, the Viterbi decoding algorithm. A "real-time," i.e., fixed decoding delay, version of the Viterbi algorithm is also developed and used for comparison to the new algorithm on simulated channels. It is shown that the new algorithm offers advantages over Viterbi decoding in soft-decision applications, such as in the inner coding system for concatenated coding. 相似文献
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《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》2006,14(10):1147-1151
Highly parallel decoders for convolutional turbo codes have been studied by proposing two parallel decoding architectures and a design approach of parallel interleavers. To solve the memory conflict problem of extrinsic information in a parallel decoder, a block-like approach in which data is written row-by-row and read diagonal-wise is proposed for designing collision-free parallel interleavers. Furthermore, a warm-up-free parallel sliding window architecture is proposed for long turbo codes to maximize the decoding speeds of parallel decoders. The proposed architecture increases decoding speed by 6%-34% at a cost of a storage increase of 1% for an eight-parallel decoder. For short turbo codes (e.g., length of 512 bits), a warm-up-free parallel window architecture is proposed to double the speed at the cost of a hardware increase of 12% 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》2009,55(6):2577-2598
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级联卷积码的性能评估 总被引:1,自引:0,他引:1
本文给出了三个采用卷积码的数字通信系统,并对其性能进行了评估.其中两个系统采用了用两个短的卷积码进行级联的方式(称为级联系统). 而另一个则是现在普遍使用的卷积编码方式,它采用一个长的卷积码(称为基联系统),三个系统的编码效率和约束长度分别采用R=2/3和K=3,R=3/4和K=2,以及R=1/2和K=7.前两个系统在Viterbi译码器进行硬件判决之前采用了软判决.两个级联系统中最为突出的特点是它们的译码器的复杂程度被大大降低,整个系统的复杂程度比基联系统改变了25%到50%. 相似文献
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