IEEE Transactions on Information Theory

Volume 39 Issue 4 • Jul 1993

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Displaying Results 1 - 25 of 41
  • A linear algebra approach to minimal convolutional encoders

    Publication Year: 1993, Page(s):1219 - 1233
    Cited by:  Papers (49)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1032 KB)

    The authors review the work of G.D. Forney, Jr., on the algebraic structure of convolutional encoders upon which some new results regarding minimal convolutional encoders rest. An example is given of a basic convolutional encoding matrix whose number of abstract states is minimal over all equivalent encoding matrices. However, this encoding matrix can be realized with a minimal number of memory el... View full abstract»

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  • Multistage decoding of multilevel block M-PSK modulation codes and its performance analysis

    Publication Year: 1993, Page(s):1204 - 1218
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1288 KB)

    Multistage decoding of multilevel block multilevel phase-shift keying (M-PSK) modulation codes for the additive white Gaussian noise (AWGN) channel is investigated. Several types of multistage decoding, including a suboptimum soft-decision decoding scheme, are devised and analyzed. Upper bounds on the probability of an incorrect decoding of a code are derived for the proposed multistage d... View full abstract»

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  • Partition function estimation of Gibbs random field images using Monte Carlo simulations

    Publication Year: 1993, Page(s):1322 - 1332
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (864 KB)

    A Monte Carlo simulation technique for estimating the partition function of a general Gibbs random field image is proposed. By expressing the partition function as an expectation, an importance sampling approach for estimating it using Monte Carlo simulations is developed. As expected, the resulting estimators are unbiased and consistent. Computations can be performed iteratively by using simple M... View full abstract»

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  • Further asymptotic upper bounds on the minimum distance of trellis codes

    Publication Year: 1993, Page(s):1428 - 1431
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    Asymptotic upper bounds on the minimum distance of trellis codes are derived. A universal bound and bounds specific to phase-shift keying (PSK) and quadrature amplitude modulation (QAM) signal sets are obtained View full abstract»

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  • Covering radius, codimension, and dual-distance width

    Publication Year: 1993, Page(s):1195 - 1203
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (544 KB)

    Upper bounds on the covering radius of codes with a given cardinality and a given dual-distance width are derived. Using an entirely new method, some results published by C. Delorme and P. Sole (1991) for linear codes are generalized, and results are derived for unrestricted codes that have no previous analogue. For some classes of codes, when the parameters lie within certain intervals, results i... View full abstract»

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  • On the capacity of a cascade of channels

    Publication Year: 1993, Page(s):1310 - 1321
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1008 KB)

    A class of information-theoretic problems is introduced that deals with systems in which information is transmitted through a series of noisy channels with limited or no processing between channels. Some basic questions that arise in such systems are examined in detail. The effects of ordering of the channels on overall capacity and the characteristics that cause channels to have high capacity whe... View full abstract»

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  • On the density of phase-space expansions

    Publication Year: 1993, Page(s):1152 - 1156
    Cited by:  Papers (25)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (332 KB)

    Phase-space decompositions for signals of finite energy have been used to formulate the intuitive but elusive idea that frequency content of a signal can vary with time as the signal evolves. The decompositions consist of subdividing the time and frequency axes into certain ranges and expanding signals stably in a two-parameter basis of fixed functions of time, in which the (k,m)... View full abstract»

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  • A relation between Levenshtein-type distances and insertion-and-deletion correcting capabilities of codes

    Publication Year: 1993, Page(s):1424 - 1427
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    A code is a collection of words or strings, not necessarily all of the same length, over come fixed alphabet. A relation is established between the insertion-and-deletion correcting capability of a code and its minimum distance for suitable Levenshtein-type distance measures View full abstract»

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  • A coding scheme for single peak-shift correction in (d, k)-constrained channels

    Publication Year: 1993, Page(s):1444 - 1450
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (712 KB)

    A two step coding scheme for peak-shift correction in (d, k)-constrained sequences is described. The first step is based on q-ary (q=k-d+1 is a prime) block codes that allow correction of specific types of double errors caused by single peak-shifts. The second step is a simple conversion of q-ary symbols to binary strings of the type 0... View full abstract»

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  • On the design of an optimal quantizer

    Publication Year: 1993, Page(s):1180 - 1194
    Cited by:  Papers (11)  |  Patents (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1312 KB)

    The problem of designing an optimal quantizer with a fixed number of levels for a wide class of error weighting functions and an arbitrary distribution function is discussed. The existence of an optimal quantizer is proved, and a two-stage algorithm for its design is suggested. In this algorithm, at the first stage, Lloyd's iterative Method I is applied for reducing the region where, at the second... View full abstract»

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  • Sliding block codes between constrained systems

    Publication Year: 1993, Page(s):1303 - 1309
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    The construction of finite-state codes between constrained systems called sofic systems introduced by R. Karabed and B. Marcus (1988) is continued. It is shown that if Σ is a shift of finite type and S is a sofic system with k/n=h(S )/h(Σ), where h denotes entropy, there is a noncatastrophic finite-state invertible code fro... View full abstract»

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  • Strong universal consistency of neural network classifiers

    Publication Year: 1993, Page(s):1146 - 1151
    Cited by:  Papers (28)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (496 KB)

    In statistical pattern recognition, a classifier is called universally consistent if its error probability converges to the Bayes-risk as the size of the training data grows for all possible distributions of the random variable pair of the observation vector and its class. It is proven that if a one-layered neural network with properly chosen number of nodes is trained to minimize the empirical ri... View full abstract»

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  • Some new lower bounds for binary and ternary covering codes

    Publication Year: 1993, Page(s):1422 - 1424
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    A modified lower bound for binary codes with covering radius one is derived. Let Kq(n,R) denote the minimum cardinality of a q-ary code with covering radius R . The new bound shows that K2(11,1)⩾177 and that K2(17,1)⩾7391, improvements of the best lower bounds known. The authors also generalize ... View full abstract»

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  • Maximum likelihood decoding of the Leech lattice

    Publication Year: 1993, Page(s):1435 - 1444
    Cited by:  Papers (26)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (804 KB)

    An algorithm for maximum likelihood decoding of the Leech lattice is presented. The algorithm involves projecting the points of the Leech lattice directly onto the codewords of the (6,3,4) quaternary code-the hexacode. Projection on the hexacode induces a partition of the Leech lattice into four cosets of a certain sublattice 24. Such a partition into cosets enables maximum likelihood decoding of ... View full abstract»

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  • Alphabet-constrained vector quantization

    Publication Year: 1993, Page(s):1167 - 1179
    Cited by:  Papers (9)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1100 KB)

    Alphabet-constrained rate-distortion theory is extended to coding of sources with memory. Two different cases are considered: when only the size of the codebook is constrained and when the codevector values are also held fixed. For both cases, nth-order constrained-alphabet rate-distortion functions are defined and a convergent algorithm for their evaluation is presented. Specific simulat... View full abstract»

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  • Normal and abnormal codes

    Publication Year: 1993, Page(s):1453 - 1456
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    It is proved that codes of length n, covering radius R, and minimum Hamming distance 2R-1 are normal if R does not divide n. Constructions for abnormal codes with covering radius R and minimum Hamming distance at least R-1 are given View full abstract»

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  • Random infinite trees and supercritical behavior of collision resolution algorithms

    Publication Year: 1993, Page(s):1460 - 1465
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (488 KB)

    An analytical evaluation is given of the behavior of the free access stack algorithm when the input load, a Poisson flow of λ packet per slot, is above the maximum throughput achievable by the protocol (within 0.360177 packet per slot) under an infinite population model. In particular, the marginal output stream that the system sustains on the channel is analytically and quantitatively deri... View full abstract»

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  • Proper complex random processes with applications to information theory

    Publication Year: 1993, Page(s):1293 - 1302
    Cited by:  Papers (499)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    The covariance of complex random variables and processes, when defined consistently with the corresponding notion for real random variables, is shown to be determined by the usual complex covariance together with a quantity called the pseudo-covariance. A characterization of uncorrelatedness and wide-sense stationarity in terms of covariance and pseudo-covariance is given. Complex random variables... View full abstract»

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  • Asymptotic results for maximum likelihood estimation with an array of sensors

    Publication Year: 1993, Page(s):1374 - 1385
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1004 KB)

    In many cases, the maximum likelihood (ML) estimator is consistent and asymptotically normal with covariance equal to the inverse of the Fisher's information matrix. It does not follow, though, that the covariance of the ML estimator approaches the Cramer-Rao lower bound as the sample size increases. However, it is possible to draw such a conclusion for the adaptive array problem in which directio... View full abstract»

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  • Vector quantization with complexity costs

    Publication Year: 1993, Page(s):1133 - 1145
    Cited by:  Papers (56)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1528 KB)

    Vector quantization is a data compression method by which a set of data points is encoded by a reduced set of reference vectors: the codebook. A vector quantization strategy is discussed that jointly optimizes distortion errors and the codebook complexity, thereby determining the size of the codebook. A maximum entropy estimation of the cost function yields an optimal number of reference vectors, ... View full abstract»

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  • A measure of relative entropy between individual sequences with application to universal classification

    Publication Year: 1993, Page(s):1270 - 1279
    Cited by:  Papers (63)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (744 KB)

    A new notion of empirical informational divergence (relative entropy) between two individual sequences is introduced. If the two sequences are independent realizations of two finite-order, finite alphabet, stationary Markov processes, the empirical relative entropy converges to the relative entropy almost surely. This empirical divergence is based on a version of the Lempel-Ziv data compression al... View full abstract»

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  • The entropy of Markov trajectories

    Publication Year: 1993, Page(s):1418 - 1421
    Cited by:  Papers (24)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (244 KB)

    The idea of thermodynamic depth put forth by S. Lloyd and H. Pagels (1988) requires the computation of the entropy of Markov trajectories. Toward this end, the authors consider an irreducible finite state Markov chain with transition matrix P and associated entropy rate H(X)=-Σi,j μiPij log Pij where ... View full abstract»

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  • Multilevel codes for unequal error protection

    Publication Year: 1993, Page(s):1234 - 1248
    Cited by:  Papers (122)  |  Patents (19)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1056 KB)

    Two combined unequal error protection (UEP) coding and modulation schemes are proposed. The first method multiplexes different coded signal constellations, with each coded constellation providing a different level of error protection. In this method, a codeword specifies the multiplexing rule and the choice of the codeword from a fixed codebook is used to convey additional important information. T... View full abstract»

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  • Noncausal Gauss Markov random fields: parameter structure and estimation

    Publication Year: 1993, Page(s):1333 - 1355
    Cited by:  Papers (51)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1884 KB)

    The parameter structure of noncausal homogeneous Gauss Markov random fields (GMRF) defined on finite lattices is studied. For first-order (nearest neighbor) and a special class of second-order fields, a complete characterization of the parameter space and a fast implementation of the maximum likelihood estimator of the field parameters are provided. For general higher order fields, tight bounds fo... View full abstract»

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  • On the nonperiodic cyclic equivalence classes of Reed-Solomon codes

    Publication Year: 1993, Page(s):1431 - 1434
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    Picking up exactly one member from each of the nonperiodic cyclic equivalence classes of an (n, k+1) Reed-Solomon code E over GF(q) gives a code, E", which has bounded Hamming correlation values and the self-synchronizing property. The exact size of E" is shown to be (1/n) Σd|n μ(d)q1+kd... 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
Prakash Narayan 

Department of Electrical and Computer Engineering