共查询到20条相似文献,搜索用时 93 毫秒
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本文确定了游程限制书写记忆介质在两种编、译码情形下的容量,作为推论证明了Cohen关于间隔书写记忆介质的容量的一个猜想。同时对游程限制书写记忆介质的陪集码构造方法进行了分析。 相似文献
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针对无线物理层安全编码不能保证信息在有噪信道下进行强安全传输的问题,该文提出一种基于部分陪集的强安全编码方法。首先证明了当且仅当陪集母码的对偶码的最小汉明距离大于信息泄露位数时,利用部分陪集编码能够保证信息的强安全传输;然后证明了陪集编码的一系列性质,基于这些性质可以将陪集间最小汉明距离计算降低为1次查表运算,进而设计了一种基于树形深度优先的最大可用陪集集合搜索算法;最后分析得出一些典型线性分组码的抗窃听信道信息泄露和抗合法信道传输噪声的能力,以及相应的最大可用陪集集合。当陪集母码为BCH(15,11)的对偶码时,与传统陪集编码方案相比,该方法对合法信道的信道质量要求降低了5 dB,同时能够保证信息传输的强安全性。 相似文献
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在低密度奇偶校验码和量子纠错理论基础上,分析了基于稀疏矩阵的量子LDPC码的构造方法,提出了一种量子CSS码的编码实现过程中有效的陪集搜索方法,以(3,8)(16,6)量子LDPC码的构造过程为例说明此陪集搜索算法的有效性,并与现有的陪集寻找算法进行了比较。数值计算结果表明,改进的陪集搜索算法在获得与传统搜索方法相近的性能情况下编码速度有了显著提高,同时克服了传统陪集搜索算法中量子码字的存储问题。 相似文献
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本文讨论的是q元狭义本原BCH码,以下简称BCH码。首先给出了一定条件下求BCH码维数的一般公式,该结果改进了MacWilliams等人(1977)的结果。然后给出了求BCH码维数的一般迭代方法。此外,本文还指出了BCH码的最小距离的BCH界是分圆陪集首,我们猜测BCH码的最小距离也是分圆陪集首。 相似文献
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本文在文献「10」的基础上,进一步探讨6PSK环码在瑞利衰落信道上的误码特性,用分量码重量集合给出了衰落条件下误码概率指数Δ的表达式,并通过例子与相同构造条件下的陪集码进行了比较,证明了在瑞利衰落条件下,环码也优于任何一种构造的陪集码。 相似文献
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本文讨论了分组陪集码在最大似然译码与最近陪集译码下的误码特性,这一分析是分别在归一化重量分布和真实距离下做出的,并对其差异进行了比较。本文同时讨论了采用最小距离和最小距离系数进行误码率估计的方法,并指出这些参数可由子码的相应汉明参数得到。 相似文献
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关于Goppa码,Alternant码最小距离下限的简化算法 总被引:3,自引:1,他引:2
文献[2]、[3]分别给出了Goppa码、Alternant码最小距离新下限。但是要求出它们的下限,都需要计算出若干个循环陪集。本文首先给出循环陪集首集A溉念,然后推出了求最小距离下限问题即是求A中第一个大于给定正整数r的元M(r)的问题。讨论了A与M(r)一系列特性,给出了一些情况下M(r)的统一公式,以及求M(r)的快速而简便的方法。通过本文讨论,求Goppa码、Alternant码最小距离下限问题得到了很大简化。此外,本文还简单地讨论了给定最小距离如何设计Goppa码、Alternant码的问题。 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1985,31(1):105-106
The construction of a class of binary linear codes for masking computer memory defects is presented. These codes are capable of masking three or fewer defects and correcting multiple random errors. 相似文献
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We consider maximal-length linear congruential sequences generated using a simple recursion to generate the bipartite graph of a low-density parity-check (LDPC) code. The main advantage is that the graph structure of the codes (edge connections) can be generated using a recursion, rather than having to store the graph connections in memory, which facilitates hardware implementation of the decoder. For this class of codes, sufficient conditions on the recursion parameters are derived, such that regular LDPC codes can be constructed with no cycles of length four or less. Simulation results show that these codes provide almost the same performance of a constrained pseudorandom construction that explicitly avoids cycles of length less than or equal to four. 相似文献
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《IEEE transactions on information theory / Professional Technical Group on Information Theory》1983,29(6):831-842
Linear block codes are studied for improving the reliability of message storage in computer memory with stuck-at defects and noise. The case when the side information about the state of the defects is available to the decoder or to the encoder is considered. In the former case, stuck-at cells act as erasures so that techniques for decoding linear block codes for erasures and errors can be directly applied. We concentrate on the complimentary problem of incorporating stuck-at information in the encoding of linear block codes. An algebraic model for stuck-at defects and additive errors is presented. The notion of a "partitioned" linear block code is introduced to mask defects known at the encoder and to correct random errors at the decoder. The defect and error correction capability of partitioned linear block codes is characterized in terms of minimum distances. A class of partitioned cyclic codes is introduced. A BCH-type bound for these cyclic codes is derived and employed to construct partitioned linear block codes with specified bounds on the minimum distances. Finally, a probabilistic model for the generation of stuck-at cells is presented. It is shown that partitioned linear block codes achieve the Shannon capacity for a computer memory with symmetric defects and errors. 相似文献
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Baggen C.P.M.J. Tolhuizen L.M.G.M. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1997,43(5):1400-1411
A Diamond code is an error-correcting code obtained from two component codes. As in a product code, any symbol in a word of a Diamond code is checked by both component codes. However, the “code directions” for the component codes have been selected to minimize the memory that is required between successive decoding stages for the component codes. Diamond codes combine the error correcting power of a product code with the reduced memory requirements of the cross interleaved Reed-Solomon code (CIRC), applied in the compact disk system. We discuss encoding, decoding, and minimum distance properties of Diamond codes. Variations on the Diamond code construction are proposed that result in codes that are suited for use in rewritable block-oriented applications 相似文献
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Comparison of constructions of irregular Gallager codes 总被引:1,自引:0,他引:1
The low-density parity check codes whose performance is closest to the Shannon limit are “Gallager codes” based on irregular graphs. We compare alternative methods for constructing these graphs and present two results. First, we find a “super-Poisson” construction which gives a small improvement in empirical performance over a random construction. Second, whereas Gallager codes normally take N2 time to encode, we investigate constructions of regular and irregular Gallager codes that allow more rapid encoding and have smaller memory requirements in the encoder. We find that these “fast encoding” Gallager codes have equally good performance 相似文献
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Ahlswede R. Balkenhol B. Ning Cai 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2002,48(4):959-962
We introduce the concept of "parallel error correcting" codes, the error correcting codes for parallel channels. Here, a parallel channel is a set of channels such that the additive error over a finite field occurs in one of its members at time T if the same error occurs in all members at the same time. The set of codewords of a parallel error correcting code has to be a product set, if the messages transmitted are from independent information sources. We present a simple construction of optimal parallel error correcting codes based on ordinary optimal error correcting codes and a construction of optimal linear parallel codes for independent sources based on optimal ordinary linear error correcting codes. The decoding algorithms for these codes are provided as well 相似文献
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Chaoping Xing Yang Fang 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2004,50(5):884-887
We present a construction of linear codes from polynomials. It turns out that some new codes are obtained from our construction and improve parameters of Brouwer's table. 相似文献
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Abdel-Ghaffar K.A.S. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1997,43(5):1489-1502
Error detection is a simple technique used in various communication and memory systems to enhance reliability. We study the probability that a q-ary (linear or nonlinear) block code of length n and size M fails to detect an error. A lower bound on this undetected error probability is derived in terms of q, n, and M. The new bound improves upon other bounds mentioned in the literature, even those that hold only for linear codes. Block codes whose undetected error probability equals the new lower bound are investigated. We call these codes strictly optimal codes and give a combinatorial characterization of them. We also present necessary and sufficient conditions for their existence. In particular, we find all values of n and M for which strictly optimal binary codes exist, and determine the structure of all of them. For example, we construct strictly optimal binary-coded decimal codes of length four and five, and we show that these are the only possible lengths of such codes 相似文献
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The authors present some properties of punctured convolutional codes, providing a construction method and a list of new, good, high-rate, long-memory punctured codes. The structure of punctured codes is examined and an upper bound on the free distance of punctured codes is derived, indicating that punctured codes are good codes. A construction method that generates the low-rate original codes which duplicate given known high-rate codes through perforation is proposed. Tables of punctured codes that duplicate the best known nonsystematic codes of rates 2/3 and 3/4 with memory lengths ranging from 3 to 23 and from 3 to 9, respectively, are given, together with the best known systematic codes for rates ranging from 2/3 to 7/8 with very long memory, M =44 through 48 相似文献
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Dettmar U. Serger U.K. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1995,41(2):591-596
We propose an algorithm for bounded minimum distance decoding of (partial) unit memory codes up to half the “designed” extended row distance. It makes use of a reduced trellis with the nodes found by bounded minimum distance decoding of the block codes used in the unit memory code. The results can be extended to general multimemory codes. The complexity of this algorithm is upper bounded by 2(d¯ 1r-2dα) times the complexity of the bounded minimum distance decoder of the block codes in the unit memory code. Here dα is the linear increase of the designed extended row distance d¯ir 相似文献