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IEEE Transactions on Information Theory

Issue 5 • Date Sep 1997

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Displaying Results 1 - 25 of 46
  • Constructions of nonlinear covering codes

    Publication Year: 1997, Page(s):1639 - 1647
    Cited by:  Papers (1)
    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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  • Optimal multiplexing on a single link: delay and buffer requirements

    Publication Year: 1997, Page(s):1518 - 1535
    Cited by:  Papers (69)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (740 KB)

    This paper is motivated by the need to provide per-session quality of service guarantees in fast packet-switched networks. We address the problem of characterizing and designing scheduling policies that are optimal in the sense of minimizing buffer and/or delay requirements under the assumption of commonly accepted traffic constraints. We investigate buffer requirements under three typical memory ... 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 hyperplane-based algorithm for the digital co-channel communications problem

    Publication Year: 1997, Page(s):1536 - 1548
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (648 KB)

    The relationship between the blind digital co-channel communications problem and the problem of finding a separating hyperplane in IRd is explored. A simple model for the blind digital co-channel communications problem is X=AS, where X is a known IR d×N matrix. A is an unknown full-rank IRd×d matrix, and S is an unknown full-rank d×N matrix with ... View full abstract»

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  • A practical method for approaching the channel capacity of constrained channels

    Publication Year: 1997, Page(s):1389 - 1399
    Cited by:  Papers (61)  |  Patents (30)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    A new coding technique is proposed that translates user information into a constrained sequence using very long codewords. Huge error propagation resulting from the use of long codewords is avoided by reversing the conventional hierarchy of the error control code and the constrained code. The new technique is exemplified by focusing on (d, k)-constrained codes. A storage-effective enumerative enco... View full abstract»

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  • Fixed-slope universal lossy data compression

    Publication Year: 1997, Page(s):1465 - 1476
    Cited by:  Papers (42)  |  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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  • Characterization of quaternary extremal codes of lengths 18 and 20

    Publication Year: 1997, Page(s):1613 - 1616
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (188 KB)

    We prove that, up to equivalence, there is a unique extremal quaternary Hermitian self-dual code of length 18, and that there are two inequivalent extremal quaternary Hermitian self-dual codes of length 20 View full abstract»

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  • Tradeoff between source and channel coding

    Publication Year: 1997, Page(s):1412 - 1424
    Cited by:  Papers (89)  |  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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  • The generalized Gilbert-Varshamov bound is implied by Turan's theorem [code construction]

    Publication Year: 1997, Page(s):1605 - 1606
    Cited by:  Papers (15)
    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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  • 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 probability-ratio approach to approximate binary arithmetic coding

    Publication Year: 1997, Page(s):1658 - 1662
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (200 KB)

    We describe an alternative mechanism for approximate binary arithmetic coding. The quantity that is approximated is the ratio between the probabilities of the two symbols. Analysis is given to show that the inefficiency so introduced is less than 0.7% on average; and in practice the compression loss is negligible View full abstract»

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  • Probabilistic crisscross error correction

    Publication Year: 1997, Page(s):1425 - 1438
    Cited by:  Papers (10)
    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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  • 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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  • 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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  • The quadratic Gaussian CEO problem

    Publication Year: 1997, Page(s):1549 - 1559
    Cited by:  Papers (140)
    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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  • 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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  • Covering numbers for real-valued function classes

    Publication Year: 1997, Page(s):1721 - 1724
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (192 KB)

    We find tight upper and lower bounds on the growth rate for the covering numbers of functions of bounded variation in the L1 metric in terms of all the relevant constants. We also find upper and lower bounds on covering numbers for general function classes over the family of L1(dP) metrics in terms of a scale-sensitive combinatorial dimension of the function class View full abstract»

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  • Long packing and covering codes

    Publication Year: 1997, Page(s):1617 - 1619
    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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  • A multiuser approach to narrowband cellular communications

    Publication Year: 1997, Page(s):1503 - 1517
    Cited by:  Papers (23)
    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 Nordstrom-Robinson code is algebraic-geometric

    Publication Year: 1997, Page(s):1588 - 1593
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    The techniques of algebraic geometry have been widely and successfully applied to the study of linear codes over finite fields since the early 1980s. There has also been an increased interest in the study of linear codes over finite rings. In a previous paper, we combined these two approaches to coding theory by introducing and studying algebraic-geometric codes over rings. We show that the Nordst... 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 (8)
    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 Diamond codes

    Publication Year: 1997, Page(s):1400 - 1411
    Cited by:  Papers (4)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (452 KB)

    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 correct... View full abstract»

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  • Is code equivalence easy to decide?

    Publication Year: 1997, Page(s):1602 - 1604
    Cited by:  Papers (9)
    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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  • 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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  • A lower bound on the undetected error probability and strictly optimal codes

    Publication Year: 1997, Page(s):1489 - 1502
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    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 t... View full abstract»

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Aims & Scope

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
Frank R. Kschischang

Department of Electrical and Computer Engineering