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IEEE Transactions on Information Theory

Issue 5 • Sep 1997

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Displaying Results 1 - 25 of 46
  • Some extended results on the search for good convolutional codes

    Publication Year: 1997, Page(s):1682 - 1697
    Cited by:  Papers (40)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (740 KB)

    We provide useful results on two classes of convolutional codes: binary codes and nonbinary codes. The best codes or the best known codes for these two classes of convolutional codes are found, by computer search. Some of them are better than those found in the past. We specify these codes by their transfer function matrices, distance spectra, and information-weight spectra. Furthermore, we derive... View full abstract»

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  • On the effect of truncation length on the exact performance of a convolutional code

    Publication Year: 1997, Page(s):1678 - 1681
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (164 KB)

    In this correspondence, we first correct a mistake in Best et al. (1995) and then present a method to compute the exact probability of information bit error as a function of truncation length K for a rate 1/2, 2 state code, Finally, we generalize the method to compute the exact bit-error probability of the above convolutional code when the information bits are transmitted in blocks. The simulation... View full abstract»

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  • Performance of explicit error detection and threshold decision in decoding with erasures

    Publication Year: 1997, Page(s):1650 - 1655
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (284 KB)

    We study the performance of two schemes for decoding with erasures: threshold decision and decision by explicit error detection. We show that the latter scheme based on error-detection coding and maximum-likelihood decoding is at least as good as the former scheme, at least for binary symmetric channels View full abstract»

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  • New extremal self-dual codes of lengths 42 and 44

    Publication Year: 1997, Page(s):1607 - 1612
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (204 KB)

    All extremal binary self-dual codes of lengths 42 and 44 which have an automorphism of order 5 with eight independent cycles are obtained up to equivalence. There are 109 inequivalent [42, 21, 8] codes with such an automorphism. All [44, 22, 8] codes that are obtained have 29 different weight enumerators View full abstract»

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  • On an approximate eigenvector associated with a modulation code

    Publication Year: 1997, Page(s):1672 - 1678
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (248 KB)

    Let S be a constrained system of finite type, described in terms of a labeled graph M of finite type. Furthermore, let C be an irreducible constrained system of finite type, consisting of the collection of possible code sequences of some finite-state-encodable, sliding-block-decodable modulation code for S. It is known that this code could then be obtained by state splitting, using a suitable appr... View full abstract»

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  • A suboptimal lossy data compression based on approximate pattern matching

    Publication Year: 1997, Page(s):1439 - 1451
    Cited by:  Papers (50)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (704 KB)

    A practical suboptimal (variable source coding) algorithm for lossy data compression is presented. This scheme is based on approximate string matching, and it naturally extends the lossless Lempel-Ziv (1977) data compression scheme. Among others we consider the typical length of an approximately repeated pattern within the first n positions of a stationary mixing sequence where D percent of mismat... View full abstract»

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  • New good quasi-cyclic ternary and quaternary linear codes

    Publication Year: 1997, Page(s):1647 - 1650
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (132 KB)

    Let [n,k,d;q]-codes be linear codes of length n, dimension k and minimum Hamming distance d over GF(q). The following quasi-cyclic codes are constructed in this paper: [44,11,20;3], [55,11:26:3], [66,11,32;3], [48,12,21;3], [60,12,28;3], [56,13,24;3], [65,13,29;3], [56,14,23;3], [60,15,23;3], [64,16,25;3], [36,9,19;4], [90,9,55;4], [99,9,61;4], [30,10,14;4], [50,10,27;4], [55,10,30;4], [33,11,15;4... View full abstract»

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  • On generalized stable nonuniform sampling expansions involving derivatives

    Publication Year: 1997, Page(s):1714 - 1716
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (144 KB)

    We establish a general sampling expansion involving derivatives for the Paley-Wiener class of functions. It can be thought of as a generalization of Rawn's (1989) result since it is based on the arbitrary sequence of desired derivative order. Also, the class of corresponding nonuniform sampling sequences is more general, i.e., more irregular than those usually encountered in literature View full abstract»

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  • New single asymmetric error-correcting codes

    Publication Year: 1997, Page(s):1619 - 1623
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (240 KB)

    New single asymmetric error-correcting codes are proposed. These codes are better than existing codes when the code length n is greater than 10, except for n=12 and n=15. In many cases one can construct a code C containing at least [2n/n] codewords. It is known that a code with |C|⩾[2n/(n+1)] can be easily obtained. It should be noted that the proposed codes for n=12 and ... View full abstract»

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  • The generalized Gilbert-Varshamov bound is implied by Turan's theorem [code construction]

    Publication Year: 1997, Page(s):1605 - 1606
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (76 KB)

    The generalization of the Gilbert-Varshamov bound due to Gu and Fuja (1993) is a direct consequence of Turan's theorem on the existence of a clique in a graph with many edges. Turan's theorem allows a slight improvement of Gu and Fuja's result. This improved generalized Gilbert-Varshamov bound is in fact equivalent to Turan's theorem View full abstract»

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  • Complementary reliability-based decodings of binary linear block codes

    Publication Year: 1997, Page(s):1667 - 1672
    Cited by:  Papers (14)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    This correspondence presents a hybrid reliability-based decoding algorithm which combines the reprocessing method based on the most reliable basis and a generalized Chase-type algebraic decoder based on the least reliable positions. It is shown that reprocessing with a simple additional algebraic decoding effort achieves significant coding gain. For long codes, the order of reprocessing required t... View full abstract»

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  • Probabilistic crisscross error correction

    Publication Year: 1997, Page(s):1425 - 1438
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (776 KB)

    The crisscross error model in data arrays is considered, where the corrupted symbols are confined to a prescribed number of rows or columns (or both). Under the additional assumption that the corrupted entries are uniformly distributed over the channel alphabet, and by allowing a small decoding error probability, a coding scheme is presented where the redundancy can get close to one half the redun... View full abstract»

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  • Constructions of nonlinear covering codes

    Publication Year: 1997, Page(s):1639 - 1647
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (516 KB)

    Constructions of nonlinear covering codes are given. Using any nonlinear starting code of covering radius R⩾2 these constructions form an infinite family of codes with the same covering radius. A nonlinear code is treated as a union of cosets of a linear code. New infinite families of nonlinear covering codes are obtained. Concepts of R,l-objects, R,l-partitions, and R,l-length are described f... View full abstract»

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  • On the aperiodic and odd correlations of the binary Shanbhag-Kumar-Helleseth sequences

    Publication Year: 1997, Page(s):1593 - 1596
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    A previously derived upper bound on hybrid sums over Galois rings is combined with a method due to Vinogradov (1954) to obtain an upper bound for the maximum aperiodic and odd correlations of the binary sequences constructed by Shanbhag, Kumar, and Helleseth (see Proc. 1995 IEEE Int. Symp. on Information Theory, 1995) View full abstract»

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  • How many information bits does a decoder need about the channel statistics?

    Publication Year: 1997, Page(s):1707 - 1714
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    We investigate the minimum amount of side information about the channel statistics that must be provided to the decoder in order to guarantee reliable communication in the random coding sense, for certain classes of channels View full abstract»

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  • Long packing and covering codes

    Publication Year: 1997, Page(s):1617 - 1619
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    We study geometrically the domain of linear binary codes and of unrestricted binary codes in the plane (normalized covering radius, normalized minimal distance) View full abstract»

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  • Fixed-slope universal lossy data compression

    Publication Year: 1997, Page(s):1465 - 1476
    Cited by:  Papers (44)  |  Patents (30)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (628 KB)

    Corresponding to any lossless codeword length function l, three universal lossy data compression schemes are presented: one is with a fixed rate, another is with a fixed distortion, and a third is with a fixed slope. The former two universal lossy data compression schemes are the generalization of Yang-Kieffer's (see ibid., vol.42, no.1, p.239-45, 1995) results to the general case of any lossless ... View full abstract»

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  • Is code equivalence easy to decide?

    Publication Year: 1997, Page(s):1602 - 1604
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (108 KB)

    We study the computational difficulty of deciding whether two matrices generate equivalent linear codes, i.e., codes that consist of the same codewords up to a fixed permutation on the codeword coordinates. We call this problem code equivalence. Using techniques from the area of interactive proofs, we show on the one hand, that under the assumption that the polynomial-time hierarchy does not colla... View full abstract»

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  • Cryptographically resilient functions

    Publication Year: 1997, Page(s):1740 - 1747
    Cited by:  Papers (36)  |  Patents (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    This correspondence studies resilient functions which have applications in fault-tolerant distributed computing, quantum cryptographic key distribution, and random sequence generation for stream ciphers. We present a number of new methods for synthesizing resilient functions. An interesting aspect of these methods is that they are applicable both to linear and nonlinear resilient functions. Our se... View full abstract»

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  • Some decomposable codes: the |a+x|b+x|a+b+x| construction

    Publication Year: 1997, Page(s):1663 - 1667
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    Codes with decomposable structure allow the use of multistage decoding procedures to achieve suboptimum bounded-distance error performance with reduced decoding complexity. This correspondence presents some new decomposable codes, including a class of distance-8 codes, that are constructed based on the |a+x|b+x|a+b+x| construction method. Some existing best codes are shown to be decomposable and h... View full abstract»

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  • Tradeoff between source and channel coding

    Publication Year: 1997, Page(s):1412 - 1424
    Cited by:  Papers (94)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (636 KB)

    A fundamental problem in the transmission of analog information across a noisy discrete channel is the choice of channel code rate that optimally allocates the available transmission rate between lossy source coding and block channel coding. We establish tight bounds on the channel code rate that minimizes the average distortion of a vector quantizer cascaded with a channel coder and a binary-symm... View full abstract»

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  • Collision-type multiple-user communications

    Publication Year: 1997, Page(s):1725 - 1736
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (452 KB)

    A collision-type multiple access system is investigated in which every user transmits symbols from a common N-ary frequency-shift-keyed signal alphabet. We present a series of information-theoretic properties of the associated mathematical channel model. In the absence of noise, we calculate a large system approximation to the sum capacity, which is used to show that, in the limit, the combining o... View full abstract»

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  • Improvements to the bounds on optimal ternary linear codes of dimension 6

    Publication Year: 1997, Page(s):1632 - 1638
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (372 KB)

    New ternary codes of dimension 6 are presented which improve the bounds on optimal linear codes. These codes belong to the class of quasi-twisted (QT) codes, and have been constructed using a greedy algorithm. This work extends previous results on QT codes of dimension 6. In particular, several new two-weight QT codes are presented. Numerous new optimal codes which meet the Griesmer bound are give... View full abstract»

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  • A multiuser approach to narrowband cellular communications

    Publication Year: 1997, Page(s):1503 - 1517
    Cited by:  Papers (25)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (684 KB)

    We compare three receivers for coded narrowband transmission affected by fading and co-channel interference. The baseline receiver is based on conventional diversity reception with maximal-ratio combining. A multiuser approach allows us to derive a maximum-likelihood multiuser receiver and its reduced-complexity suboptimal version. Finally, a decorrelating diversity receiver, which seeks a tradeof... View full abstract»

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  • The quadratic Gaussian CEO problem

    Publication Year: 1997, Page(s):1549 - 1559
    Cited by:  Papers (150)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (588 KB)

    A firm's CEO employs a team of L agents who observe independently corrupted versions of a data sequence {X(t)}t=1∞ . Let R be the total data rate at which the agents may communicate information about their observations to the CEO. The agents are not allowed to convene. Berger, Zhang and Viswanathan (see ibid., vol.42, no.5, p.887-902, 1996) determined the asymptotic beh... View full abstract»

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IEEE Transactions on Information Theory publishes papers concerned with the transmission, processing, and utilization of information.

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Meet Our Editors

Editor-in-Chief
Prakash Narayan 

Department of Electrical and Computer Engineering