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IEEE Transactions on Information Theory

Issue 5 • Date Sept. 1995

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Displaying Results 1 - 25 of 33
  • Comments on "A lower bound on the minimum Euclidean distance of trellis-coded modulation schemes"

    Publication Year: 1995, Page(s):1531 - 1535
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (363 KB)

    Commentson a paper by Rouanne and Costello Jr. (IEEE Trans. Inform. Theory, vol.34, p.1011-20, 1988). It is shown that the derivation in the above paper is incorrect and hence the lower bound obtained is not valid for general trellis-coded modulation schemes. A corrected bound is presented to remedy this flaw. Also shown is a similar lower bound derived from the average distance structure. Both bo... 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 (280 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 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 (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (149 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 View full abstract»

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  • Groups of complex integers used as QAM signals

    Publication Year: 1995, Page(s):1512 - 1517
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (413 KB)

    Block codes which allow error correction in a two-dimensional QAM signal space are given. The properties of these codes are used to demodulate QAM signals in a differentially coherent detection scheme on a noisy channel. The block codes presented are not group codes; however, their components belong to a group Gn or G'n which is constructed starting from the Gaussian integers... 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 (590 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 View full abstract»

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  • On the odd and the aperiodic correlation properties of the Kasami sequences

    Publication Year: 1995, Page(s):1506 - 1508
    Cited by:  Papers (31)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (217 KB)

    Derives a new upper bound for the odd and the aperiodic correlations of binary sequences in the small Kasami family. The approach is based on a technique described in S. Litsyn and A. Tietavainen (1994) that is originally due to I.M. Vinogradov (1954). An essential ingredient in this method is a good upper bound on the discrete Fourier coefficients of a shifted product of a pair of sequences. The ... View full abstract»

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  • On the capacity of M-ary runlength-limited codes

    Publication Year: 1995, Page(s):1508 - 1511
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    Presents two results on the Shannon capacity of M-ary (d,k) codes. First the authors show that 100% efficient fixed-rate codes are impossible for all values of (M,d,k), 0⩽d<k<∞, M<∞, thereby extending a result of Ashley and Siegel (1987) to M-ary channels. Second, they show that for k=∞, there exist an infinite number of 100% efficient M-ary (d,k) codes, and they con... 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 (64)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1562 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 thi... 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 (402 KB)

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

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  • A new approach to the design of codes for synchronous-CDMA systems

    Publication Year: 1995, Page(s):1503 - 1506
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (282 KB)

    A new approach to increase the sum rate for conventional synchronous code-division multiple-access (S-CDMA) systems is presented. It is shown that it can be done by joint processing of the outputs of matched filters, when one considers the system of codes for S-CDMA to be the codes for the usual adder channel. An example of construction and decoding of such a system is also given 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 (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1201 KB)

    Universal bounds for the cardinality of codes in the Hamming space Frn 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 co... 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 (18)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (405 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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  • On the distance distribution of codes

    Publication Year: 1995, Page(s):1467 - 1472
    Cited by:  Papers (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (398 KB)

    The distinct distribution of a binary code C is the sequence (B i)i=0n defined as follows: let Bi (w) be the number of codewords at distance i from the codeword w, and let Bi be the average of Bi(w) over all w in C. In this correspondence we study the distance distribution for codes of length n and minimal distance δn, with &d... View full abstract»

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  • Repeated communication and Ramsey graphs

    Publication Year: 1995, Page(s):1276 - 1289
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1035 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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  • 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 (654 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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  • 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 (221 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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  • New 16-PSK group trellis codes

    Publication Year: 1995, Page(s):1517 - 1523
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (576 KB)

    The theory of group codes simplifies the construction of good rotationally invariant trellis codes for the additive white Gaussian noise channel. New geometrically uniform trellis codes, with spectral efficiency 3 bits/2D, based on multidimensional L×16-PSK constellations in 4, 6, and 8 dimensions, obtained by group trellis codes over nonbinary groups of the kind Z16L, ... 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 (48)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (883 KB)

    Fractional Brownian motion (fBm) provides a useful model for processes with strong long-term dependence, such as 1/fβ 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 proce... View full abstract»

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  • 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 (2578 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 Rn as the orbit of a bi-infinite “seed sequence”, x0∈(R n)Z, under an infinite, defining group of transformations. This group of transformations is generated by a s... 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 (44)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (718 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 pro... 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 (386 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 View full abstract»

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  • On the key equation

    Publication Year: 1995, Page(s):1290 - 1302
    Cited by:  Papers (42)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (872 KB)

    We consider the set M={(a, b):a≡bh mod x2t} of all solutions of the key equation for alternant codes, where h is the syndrome polynomial. In decoding these codes a particular solution (ω, σ)∈M is sought, subject to ω and σ being relatively prime and satisfying certain degree conditions. We prove that these requirements specify (ω, σ) unique... View full abstract»

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  • Generalized partial spreads

    Publication Year: 1995, Page(s):1482 - 1487
    Cited by:  Papers (30)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (414 KB)

    We exhibit a simple condition under which the sum (modulo 2) of characteristic functions of (n/2)-dimensional vector subspaces of (GF(2))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... View full abstract»

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  • Some issues related to fixed-rate pruned tree-structured vector quantizers

    Publication Year: 1995, Page(s):1523 - 1531
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (711 KB)

    It is shown that the generalized BFOS algorithm is not optimal when it is used to design fixed-rate pruned tree-structured vector quantizers (PTSVQ). A simple modification is made in the algorithm which makes it optimal. However, experimental results show little difference between the rate-distortion curves generated with the original algorithm and the one proposed in the present paper. An asympto... View full abstract»

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  • Linear block codes over cyclic groups

    Publication Year: 1995, Page(s):1246 - 1256
    Cited by:  Papers (23)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (833 KB)

    The main building block for the construction of a geometrically uniform coded modulation scheme is a subgroup of GI, 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... 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