IEEE Transactions on Information Theory

Volume 41 Issue 5 • Sept. 1995

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Displaying Results 1 - 25 of 33
  • Trellis group codes for the Gaussian channel

    Publication Year: 1995, Page(s):1217 - 1245
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (3020 KB)

    In this paper, trellis group codes are introduced as an extension of Slepian group codes to codes over sequence spaces. A trellis group code is defined over R/sup n/ as the orbit of a bi-infinite "seed sequence", x/sub 0//spl isin/(R/sup n/)/sup Z/, under an infinite, defining group of transformations. This group of transformations is generated by a symbolic system. The theory is developed by comb... View full abstract»

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  • Linear block codes over cyclic groups

    Publication Year: 1995, Page(s):1246 - 1256
    Cited by:  Papers (27)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1000 KB)

    The main building block for the construction of a geometrically uniform coded modulation scheme is a subgroup of G/sup I/, where G is a group generating a low-dimensional signal constellation and I is an index set. In this paper we study the properties of these subgroups when G is cyclic. We exploit the fact that any cyclic group of q elements is isomorphic to the additive group of Z/sub q/ (the r... View full abstract»

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  • Multilevel construction of block and trellis group codes

    Publication Year: 1995, Page(s):1257 - 1264
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (823 KB)

    The theory of group codes has been shown to be a useful starting point for the construction of good geometrically uniform codes. In this paper we study the problem of building multilevel group codes, i.e., codes obtained combining separate coding at different levels in such a way that the resulting code is a group code. A construction leading to multilevel group codes for semi-direct and direct pr... View full abstract»

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  • Decomposition of M-ary CPM signals into PAM waveforms

    Publication Year: 1995, Page(s):1265 - 1275
    Cited by:  Papers (132)  |  Patents (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (757 KB)

    It is widely known that minimum shift keying (MSK) may be seen as a PAM signaling scheme and that the same is true, albeit approximately, with MSK-like modulations. It is also known (perhaps not so widely) that any binary continuous phase-modulated (CPM) signal may be exactly decomposed into the sum of a few PAM waveforms. In this paper we show that this property extends to multilevel CPM signalin... View full abstract»

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  • Repeated communication and Ramsey graphs

    Publication Year: 1995, Page(s):1276 - 1289
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1254 KB)

    We study the savings afforded by repeated use in two zero-error communication problems. We show that for some random sources, communicating one instance requires arbitrarily many bits, but communicating multiple instances requires roughly 1 bit per instance. We also exhibit sources where the number of bits required for a single instance is comparable to the source's size, but two instances require... View full abstract»

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  • On the key equation

    Publication Year: 1995, Page(s):1290 - 1302
    Cited by:  Papers (47)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1062 KB)

    We consider the set M.<<ETX>> View full abstract»

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  • Krawtchouk polynomials and universal bounds for codes and designs in Hamming spaces

    Publication Year: 1995, Page(s):1303 - 1321
    Cited by:  Papers (53)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1473 KB)

    Universal bounds for the cardinality of codes in the Hamming space F/sub r//sup n/ with a given minimum distance d and/or dual distance d' are stated. A self-contained proof of optimality of these bounds in the framework of the linear programming method is given. The necessary and sufficient conditions for attainability of the bounds are found. The parameters of codes satisfying these conditions a... View full abstract»

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  • Generating random bits from an arbitrary source: fundamental limits

    Publication Year: 1995, Page(s):1322 - 1332
    Cited by:  Papers (54)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (869 KB)

    Suppose we are given a random source and want to use it as a random number generator; at what rate can we generate fair bits from it? We address this question in an information-theoretic setting by allowing for some arbitrarily small but nonzero deviation from "ideal" random bits. We prove our results with three different measures of approximation between the ideal and the obtained probability dis... View full abstract»

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  • On the generalized symmetric cutoff rate for finite-state channels

    Publication Year: 1995, Page(s):1333 - 1346
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1004 KB)

    Finite-state discrete-time channels with equiprobable M-ary inputs are considered. The generating function bound, which is ubiquitously applied to upper-bound the error probability of uncoded signaling over these channels, is used here to lower-bound the corresponding generalized symmetric cutoff rate, which lower-bounds the practically achievable rates and error exponents in these channels with s... View full abstract»

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  • Good error-detection codes satisfying the expurgated bound

    Publication Year: 1995, Page(s):1347 - 1353
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (567 KB)

    A q-ary (n, k) linear code is said to be proper if, as an error-detection code, the probability of undetectable error P/sub ud/ satisfies P/sub ud//spl les/q/sup -(n-k)/ for completely symmetric channels. We show that a proper code, as an error-correction code, satisfies the expurgated bound on the decoding error probability for a class of channels with the associated Bhattacharyya distance being ... View full abstract»

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  • On the construction of bounded-delay encodable codes for constrained systems

    Publication Year: 1995, Page(s):1354 - 1378
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2627 KB)

    We present a new technique to construct sliding-block modulation codes with a small decoding window. Our method, which involves both state splitting and look-ahead encoding, crucially depends on a new "local" construction method for bounded-delay codes. We apply our method to construct several new codes, all with a smaller decoding window than previously known codes for the same constraints at the... View full abstract»

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  • Soft-decision decoding of linear block codes based on ordered statistics

    Publication Year: 1995, Page(s):1379 - 1396
    Cited by:  Papers (247)  |  Patents (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1624 KB)

    Presents a novel approach to soft decision decoding for binary linear block codes. The basic idea is to achieve a desired error performance progressively in a number of stages. For each decoding stage, the error performance is tightly bounded and the decoding is terminated at the stage where either near-optimum error performance or a desired level of error performance is achieved. As a result, mor... View full abstract»

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  • Efficiency of data-aided timing recovery techniques

    Publication Year: 1995, Page(s):1397 - 1408
    Cited by:  Papers (8)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1107 KB)

    This paper assesses the tracking capabilities of data-aided timing recovery schemes in terms of an efficiency that characterizes, coarsely speaking, the amount of timing information that the scheme manages to extract from the incoming signal per unit of time and signal-to-noise ratio. Efficiencies of maximum-likelihood and various baud-rate timing recovery schemes are determined as a function of t... View full abstract»

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  • Simultaneous estimation of echo path and channel responses using full-duplex transmitted training data sequences

    Publication Year: 1995, Page(s):1409 - 1417
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (794 KB)

    To reduce the system initialization time in high-speed full-duplex data transmission over two-wire lines, we propose an efficient full-duplex fast training algorithm which can simultaneously estimate the impulse responses of echo paths and channels at both ends. Two mutually orthogonal periodic sequences are designed and used to co-estimate the near echo, the far echo with bulk delay, and the chan... View full abstract»

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  • Spread-signature CDMA: efficient multiuser communication in the presence of fading

    Publication Year: 1995, Page(s):1418 - 1438
    Cited by:  Papers (67)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1857 KB)

    A new class of orthogonal code-division multiple-access (CDMA) systems is developed for efficient multiuser communication in environments subject to multipath fading phenomena. The key characteristic of these new systems, which we refer to as "spread-signature CDMA" systems, is that the associated signature sequences are significantly longer than the interval between symbols. Using this approach, ... View full abstract»

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  • Spectral representation of fractional Brownian motion in n dimensions and its properties

    Publication Year: 1995, Page(s):1439 - 1451
    Cited by:  Papers (58)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1054 KB)

    Fractional Brownian motion (fBm) provides a useful model for processes with strong long-term dependence, such as 1/f/sup /spl beta// spectral behavior. However, fBm's are nonstationary processes so that the interpretation of such a spectrum is still a matter of speculation. To facilitate the study of this problem, another model is provided for the construction of fBm from a white-noise-like proces... View full abstract»

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  • The expansion factor of error-control codes

    Publication Year: 1995, Page(s):1452 - 1457
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (501 KB)

    We investigate the expansion factor /spl Delta/(C) of an (n, k, d) linear block code. /spl Delta/(C) indicates how well the code preserves and expands the distance relations of the input. We relate /spl Delta/(C) to n, k, d, the total weight, and the weight distribution, and we find bounds on /spl Delta/(C).<<ETX>> View full abstract»

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  • On the minimum bit-error rate of linear codes

    Publication Year: 1995, Page(s):1457 - 1466
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (732 KB)

    We investigate the bit-error rate (BER) of linear block codes. The BER is a function of the encoder realization of the code. We express the BER in terms of the weight profiles of the subspaces of the code. We also discuss the relation between the Hadamard transform and the BER.<<ETX>> View full abstract»

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  • On the accuracy of the binomial approximation to the distance distribution of codes

    Publication Year: 1995, Page(s):1472 - 1474
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (199 KB)

    The binomial distribution is a well-known approximation to the distance spectra of many classes of codes. We derive a lower estimate for the deviation from the binomial approximation.<<ETX>> View full abstract»

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  • Weight hierarchy of a product code

    Publication Year: 1995, Page(s):1475 - 1479
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (354 KB)

    Formulas to compute the first members of the weight hierarchy of a product code are given and proved. Basic patterns for the supports of subcodes in which the minimum cardinalities can be found are presented. Hence, formulas for every term of the hierarchy can be given, and the proof for each case will be a generalization of the proofs shown here.<<ETX>> View full abstract»

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  • Computing the weight distribution of a set of points obtained by scaling, shifting, and truncating a lattice

    Publication Year: 1995, Page(s):1480 - 1482
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (282 KB)

    A method is developed to compute the weight distribution of a set of points obtained from a lattice. The lattice is scaled (with possibly nonequal factors) along different dimensions, is shifted to an arbitrary point, and its lower dimensional subspaces are truncated within given shaping regions. Each branch in the lattice trellis diagram is labeled by the weight distribution of the corresponding ... View full abstract»

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  • Generalized partial spreads

    Publication Year: 1995, Page(s):1482 - 1487
    Cited by:  Papers (32)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (523 KB)

    We exhibit a simple condition under which the sum (modulo 2) of characteristic functions of (n/2)-dimensional vector subspaces of (GF(2))/sup n/ (n even) is a Bent function. The "Fourier" transform of such a Bent function is the sum of the characteristic functions of the duals of these spaces. The class of Bent functions that we obtain contains the whole partial spreads class. Any element of Maior... View full abstract»

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  • On Z/sub 4/-duality

    Publication Year: 1995, Page(s):1487 - 1494
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (628 KB)

    Recently the notion on binary codes called Z/sub 4/-linearity was introduced. This notion explains why Kerdock codes and Delsarte-Goethals codes admit formal duals in spite of their nonlinearity. The "Z/sub 4/-duals" of these codes (called "Preparata" and "Goethals" codes) are new nonlinear codes which admit simpler decoding algorithms than the previously known formal duals (the generalized Prepar... View full abstract»

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  • Even more efficient bounded-distance decoding of the hexacode, the Golay code, and the Leech lattice

    Publication Year: 1995, Page(s):1495 - 1499
    Cited by:  Papers (21)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (497 KB)

    We present a new bounded-distance decoding algorithm for the hexacode, which requires at most 34 real operations in the worst case, as compared to 57 such operations in the best previously known decoder. The new algorithm is then employed for bounded-distance decoding of the Leech lattice and the Golay code. The error-correction radius of the resulting decoders is equal to that of a maximum-likeli... View full abstract»

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  • Modified generalized concatenated codes and their application to the construction and decoding of LUEP codes

    Publication Year: 1995, Page(s):1499 - 1503
    Cited by:  Papers (2)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (485 KB)

    Proposes a modification of generalized concatenated codes, which allows to construct some of the best known binary codes in a simple way. Furthermore, a large class of optimal linear unequal error protection codes (LUEP codes) can easily be generated. All constructed codes can be efficiently decoded by the Blokh-Zyablov-Zinov'ev algorithm if an appropriate metric is used.<<ETX>> 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.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Alexander Barg

Department of Electrical and Computer Engineering and the Institute for Systems Research, University of Maryland

email: abarg-ittrans@ece.umd.edu