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IEEE Transactions on Information Theory

Issue 4 • July 1987

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Displaying Results 1 - 15 of 15
  • The capacity of the Hopfield associative memory

    Publication Year: 1987, Page(s):461 - 482
    Cited by:  Papers (505)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (3330 KB)

    Techniques from coding theory are applied to study rigorously the capacity of the Hopfield associative memory. Such a memory storesn-tuple ofpm 1's. The components change depending on a hard-limited version of linear functions of all other components. With symmetric connections between components, a stable state is ultimately reached. By building up the connection matrix as a... View full abstract»

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  • Trellis-coded modulation with multidimensional constellations

    Publication Year: 1987, Page(s):483 - 501
    Cited by:  Papers (260)  |  Patents (84)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2395 KB)

    Trellis-coded modulation schemes using four-, eight-, or16-dimensional constellations have a number of potential advantages over the usual two-dimensional schemes: a smaller constituent two-dimensional constellation, easier tolerance to phase ambiguities, and a better trade-off between complexity and coding gain. A number of such schemes are presented and evaluated. Starting with a vari... View full abstract»

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  • New results in binary multiple descriptions

    Publication Year: 1987, Page(s):502 - 521
    Cited by:  Papers (118)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2203 KB)

    An encoder whose input is a binary equiprobable memoryless source produces one output of rateR_{1}and another of rateR_{2}. LetD_{1}, D_{2}, and D_{0}, respectively, denote the average error frequencies with which the source data can be reproduced on the basis of the encoder output of rateR_{l}only, the encoder output of rateR_{2}only, and bot... View full abstract»

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  • Robust source coding of weakly compact classes

    Publication Year: 1987, Page(s):522 - 530
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1470 KB)

    A fixed-rate block code is said to be strongly robust for a class of sourcesLambdaif its maximum distortion overLambdah is no larger than the maximum of the distortion-rate functions of the sources in the class at the rate of the code. It is shown that such codes exist at all positive rates whenever the class is compact with resect to the topology of weak convergence and sati... View full abstract»

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  • On the relationship between the efficiency measures of multicategory information systems

    Publication Year: 1987, Page(s):531 - 538
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1075 KB)

    The concepts of efficiency measures of multicategory information systems and similarity measures between two efficiency measures are introduced and developed. The relationship between two efficiency measures is defined by the corresponding setD, and the appropriate marginal functions are introduced. An earlier work of Ben-Bassat's dealing with the ranking of features according to featur... View full abstract»

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  • On codes with spectral nulls at rational submultiples of the symbol frequency

    Publication Year: 1987, Page(s):557 - 568
    Cited by:  Papers (48)  |  Patents (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1730 KB)

    In digital data transmission (respectively, storage systems), line codes (respectively, recording codes) are used to tailor the spectrum of the encoded sequences to satisfy constraints imposed by the channel transfer characteristics or other system requirements. For instance, pilot tone insertion requires codes with zero mean and zero spectral density at tone frequencies. Embedded tracking/focus s... View full abstract»

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  • Cutoff points for roll call protocols in multiple access systems

    Publication Year: 1987, Page(s):577 - 581
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (666 KB)

    A communication network with multiple users sharing a common broadcast channel is considered. Ak-channel is defined to be a channel that can carry up tok-1successful transmissions simultaneously, but simultaneous transmissions bykor more users cause a collision and no successful transmissions take place. The question arises as to how to organize transmissions to av... View full abstract»

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  • Range and error analysis for a fast Fourier transform computed overZ[{omega}]

    Publication Year: 1987, Page(s):582 - 590
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1246 KB)

    A range and error analysis is developed for a discrete Fourier transform (fast Fourier transform) computed using the ring of cyclotomic integers. Included are derivations of both deterministic and statistical upper bounds for the range of the resulting processor and formulas for the ratio of the mean square error to mean square signal, in terms of the pertinent parameters. Comparisons of theoretic... View full abstract»

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  • Comparison of generalized Q- function algorithms (Corresp.)

    Publication Year: 1987, Page(s):591 - 596
    Cited by:  Papers (40)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1007 KB)

    Several methods have been proposed for calculating the generalizedQ-functionQ_{m}(alpha, beta), but only isolated comparisons of the various techniques have been reported. The accuracy, range, and execution time of prominent methods for computing theQ-function are compared, and limitations of the algorithms are identified. View full abstract»

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  • A note on the Shannon capacity of run-length-limited codes (Corresp.)

    Publication Year: 1987, Page(s):601 - 605
    Cited by:  Papers (31)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (849 KB)

    It is proven that 100-percent efficient fixed-rate codes for run-length-limited (RLL)(d,k)and RLL charge-constrained(d, k; c)channels are possible in only two eases, namely(d,k; c)=(0,1;1)and(1,3;3). Specifically, the binary Shannon capacity of RLL(d, k)constrained systems is shown to be irrational for all values of... View full abstract»

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  • Remarks on codes from Hermitian curves (Corresp.)

    Publication Year: 1987, Page(s):605 - 609
    Cited by:  Papers (50)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (562 KB)

    Parameters and generator matrices are given for the codes obtained by applying Goppa's algebraic-geometric construction method to Hermitian curves in PG(2,q), whereq = 2^{2s}for somesin {bf N}. Automorphisms of these codes are also discussed, and some results on self-duality and weak self-duality are given. View full abstract»

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  • Measures of mutual and causal dependence between two time series (Corresp.)

    Publication Year: 1987, Page(s):598 - 601
    Cited by:  Papers (26)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (744 KB)

    New measures are proposed for mutual and causal dependence between two time series, based on information theoretical ideas. The measure of mutual dependence is shown to be the sum of the measure of unidirectional causal dependence from the first time series to the second, the measure of unidirectional causal dependence from the second to the first, and the measure of instantaneous causal dependenc... View full abstract»

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  • Some inequalities concerning random subsets of a set (Corresp.)

    Publication Year: 1987, Page(s):596 - 598
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (456 KB)

    A class of plausible inequalities between conditional probabilities is considered involving random subsets of a set which arise, for example, in studying the capacity of a multiple access channel. Some of the inequalities are true and can be proved by the Fortuin-Kasteleyn-Ginibre (FKG) inequality. Some others are true but seem to need other methods. Still others are false. The results also apply ... View full abstract»

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  • Asymptotic zero distribution of orthogonal polynomials in sinusoidal frequency estimation

    Publication Year: 1987, Page(s):569 - 576
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1232 KB)

    It is shown that the zeros of polynomials orthogonal with respect to certain positive measures on the unit circle have an asymptotic distribution which is uniform on a circle of radius less than or equal to one. These results explain some phenomena observed when various linear prediction methods are used to estimate sinusoidal frequencies. They also describe the asymptotic zero distribution of the... View full abstract»

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  • Signal set design for band-limited memoryless multiple-access channels with soft decision demodulation

    Publication Year: 1987, Page(s):539 - 556
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2328 KB)

    Signal sets are identified that maximize the cutoff rate region for a multiple-access channel with an additive white Gaussian noise, in which the demodulator output alphabet is allowed to be infinite ("infinitely soft decisions"). The optimizing designs consist of a simplex signal set for each sender, such that each sender's set is orthogonal to those of the other senders. For "second moment" and ... 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