IEEE Transactions on Information Theory

Volume 21 Issue 4 • July 1975

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Displaying Results 1 - 25 of 34
  • Sliding-block source coding

    Publication Year: 1975, Page(s):357 - 368
    Cited by:  Papers (53)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (4021 KB)

    Both noiseless source coding and source coding with a fidelity criterion are traditionally accomplished via the mapping of consecutive nonoverlapping source blocks into code blocks of fixed or variable length. Here we use an easy application and interpretation of the Kolmogorov-Ornstein isomorphism theorem of ergodic theory to prove the existence of a new class of noiseless source coding technique... View full abstract»

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  • Uniformly reasonable source encoding is often practically impossible

    Publication Year: 1975, Page(s):368 - 373
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1803 KB)

    The decoding of efficiently encoded messages, from either probabilistic, nonprobabilistic, or unknown message sources, is shown to be often practically impossible. If<tex>\tau(S)</tex>is a running-time bound on the computational effort of a decoder<tex>\Psi</tex>accepting a codeword<tex>P</tex>for message<tex>S</tex>, and<tex>\gamma[K_{\Psi}(S)... View full abstract»

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  • On tree coding with a fidelity criterion

    Publication Year: 1975, Page(s):373 - 378
    Cited by:  Papers (19)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1716 KB)

    This paper reexamines Jelinek's proof that tree codes can be used to approach the rate-distortion bound. It is shown that the branching process used in Jelinek's proof is not a (strict-sense) branching process (SSBP) when the source is asymmetric. Branching processes with random environments (BPWRE) are introduced and used to extend the proof to general discrete-time memoryless sources. The theory... View full abstract»

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  • Tree encoding of speech

    Publication Year: 1975, Page(s):379 - 387
    Cited by:  Papers (109)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2605 KB)

    Recently developed methods of tree source coding with a fidelity criterion are applied to speech coding. We first demonstrate that tree codes are inherent in A-D speech convertors of the waveform following type and point to ordinary and adaptive delta modulation and differential pulse code modulation (DPCM) as examples. Insights of coding theory improve these trees at low rates; we offer two new c... View full abstract»

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  • Random coding strategies for minimum entropy

    Publication Year: 1975, Page(s):388 - 391
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1069 KB)

    This paper proves that there exists a fixed random coding Strategy for block coding a memoryless information source to achieve the absolute epsilon entropy of the source. That is, the strategy can be chosen independent of the block length. The principal new tool is an easy result on the semicontinuity of the relative entropy functional of one probability distribution with respect to another. The t... View full abstract»

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  • Distinguishable codeword sets for shared memory

    Publication Year: 1975, Page(s):392 - 399
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2558 KB)

    In data processing, a transmitter<tex>T</tex>andreceiver<tex>R</tex>communicate via a random-access memory<tex>m</tex>that they share with a set<tex>U</tex>of other users.<tex>T</tex>selects a codeword<tex>c</tex>from a set<tex>C</tex>known to<tex>R</tex>and stores<tex>c</tex>in some of the ... View full abstract»

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  • An achievable rate region for the broadcast channel

    Publication Year: 1975, Page(s):399 - 404
    Cited by:  Papers (93)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1511 KB)

    Let<tex>p(y_1, y_2 \mid x)</tex>denote a discrete memoryless channel with a single source<tex>X</tex>and two independent receivers<tex>Y_1</tex>and<tex>Y_2</tex>. We exhibit an achievable region of rates<tex>(R_{11},R_{12},R_{22})</tex>at which independent information can be sent, respectively, to receiver 1, to both receivers 1 and 2, an... View full abstract»

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  • Decoding for channels with insertions, deletions, and substitutions with applications to speech recognition

    Publication Year: 1975, Page(s):404 - 411
    Cited by:  Papers (99)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2536 KB)

    A model for channels in which an input sequence can produce output sequences of varying length is described. An efficient computational procedure for calculating Pr<tex>\{Y\mid X\}</tex>is devised, where<tex>X = x_1,x_2,\cdots,x_M</tex>and<tex>Y = y_1,y_2,\cdots,y_N</tex>are the input and output of the channel. A stack decoding algorithm for decoding on such cha... View full abstract»

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  • Some results on the problem of constructing asymptotically good error-correcting codes

    Publication Year: 1975, Page(s):412 - 417
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1521 KB)

    Justesen has shown that concatenating a class of binary codes with a Reed-Solomon (RS) code produces asymptotically good codes. For low rates, the value of the ratio of minimum distance to code length<tex>(d/n)</tex>for such codes is substantially lower than that known to be achievable by the Zyablov bound. In this paper, we present a small class of binary codes with some useful proper... View full abstract»

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  • Generalized bandpass filters for decoding block codes

    Publication Year: 1975, Page(s):417 - 422
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1748 KB)

    We show that the optimum decoder for a linear code over a finite field can be implemented by a bank of bandpass filters that are defined in a generalized frequency domain. This decoder has a fixed signal processing structure and uses complex-valued arithmetic operations instead of the usual finite field ones, This structure closely resembles one of the usual digital filter mechanizations. The emph... View full abstract»

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  • Maximum-likelihood syntactic decoding

    Publication Year: 1975, Page(s):423 - 430
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2383 KB)

    A model of a linguistic information source is proposed as a grammar that generates a language over some finite alphabet. It is pointed out that grammatical sentences generated by the source grammar contain intrinsic "redundancy" that can be exploited for error-corrections. Symbols occurring in the sentences are composed according to some syntactic rules determined by the source grammar, and hence ... View full abstract»

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  • A class of nonparametric detectors for dependent input data

    Publication Year: 1975, Page(s):431 - 437
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (2117 KB)

    A class of nonparametric detectors is formulated for dependent input sequences of sampled data. Detectors in this class are nonadaptive modifications of standard nonparametric detectors designed for independent inputs and operate on multivariate samples derived by grouping the dependent univariate input samples. These groups are transformed to single variables and processed according to the corres... View full abstract»

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  • Nonparametric estimates of probability densities

    Publication Year: 1975, Page(s):438 - 440
    Cited by:  Papers (41)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (749 KB)

    A disadvantage of the kernel estimate of a probability density is that the degree of smoothing about the observation points is chosen without regard to the data. A modification of the kernel estimate is proposed that allows the data to play a role in this smoothing and, at the same time, retains the desirable features of the kernel estimate. View full abstract»

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  • The upper error bound of a new near-optimal code

    Publication Year: 1975, Page(s):441 - 445
    Cited by:  Papers (44)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1304 KB)

    A code is implicitly constructed' from a lattice and its Dirichlet regions and, for Gaussian noise, the worst error probability of any code point is upperbounded in closed form by a chi-square distribution. The bound shows that fairly efficient codes can be obtained, particularly, at high signal-to-noise ratio (SNR) the bound approaches asymptotically the error bound of an optimal code. The deriva... View full abstract»

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  • A nonlinear fixed-lag smoother for finite-state Markov processes

    Publication Year: 1975, Page(s):446 - 452
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1997 KB)

    The fixed-lag smoothing of random telegraph type signals is studied. The smoothers are derived by first obtaining fixed-point smoothing equations and then using a time discretization. Simulation results are described that verify the qualitative carry-over of known results for the linear-Gaussian problem: the greater the lag, the greater the improvement; beyond a certain lag, no further improvement... View full abstract»

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  • Some cross correlation properties for distorted signals

    Publication Year: 1975, Page(s):453 - 458
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1347 KB)

    For a nondecreasing distortion characteristic<tex>\phi(\cdot)</tex>and a given signal<tex>x(\cdot)</tex>, the "cross correlation" function defined by<tex>R_{\phi} (\tau) \triangleq \int_{-\infty}^{\infty} \phi[x(t)]x(t - \tau) dt</tex>is shown to satisfy the inequality<tex>R_{\phi}(\tau) \leq R_{\phi}(0)</tex>, for all<tex>\tau</tex>, gen... View full abstract»

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  • On the continuity of the error distortion function for multiple-hypothesis decisions (Corresp.)

    Publication Year: 1975, Page(s):458 - 460
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (705 KB)

    Analogously to the rate distortion function, the error distortion function is defined for a multiple-hypothesis decision problem. The error distortion function<tex>e(d)</tex>is defined as the supremum of the Bayes' error probability for transformed observations for which the average distortion is less than<tex>d (d \geq O)</tex>The main result is that the function<tex>... View full abstract»

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  • Hybrid low autocorrelation sequences (Corresp.)

    Publication Year: 1975, Page(s):460 - 462
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (867 KB)

    Skew-symmetric sequences of<tex>(2n + 1)</tex>terms,<tex>a_0,a_1,\cdots,a_{2n}</tex>, are described for which the "merit factor" \begin{equation} F_h = \frac{\biggl[\sum_{i=0}^{2n} \mid a_i \mid \biggr] ^2}{ 2 \sum_{k=1}^{2n} \biggl[ \sum_{i=0}^{2n-k} \text{sign} (a_i) \cdot a_{i+k} \biggl] ^2} \end{equation} is unusually high. View full abstract»

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  • On some properties of self-reciprocal polynomials (Corresp.)

    Publication Year: 1975, Page(s):462 - 464
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (912 KB)

    Self-reciprocal polynomials (SRP's) are used to generate reversible codes with a read backward property. We characterize all the irreducible SRP's of a given degree<tex>r</tex>. Furthermore, a method of obtaining a maximal exponent SRP is presented. A short table lists the maximal exponents of SRP's of degree up to<tex>r = 34</tex>. View full abstract»

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  • Robustly optimal rate one-half binary convolutional codes (Corresp.)

    Publication Year: 1975, Page(s):464 - 468
    Cited by:  Papers (42)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1298 KB)

    Three optimality criteria for convolutional codes are considered in this correspondence: namely, free distance, minimum distance, and distance profile. Here we report the results of computer searches for rate one-half binary convolutional codes that are "robustly optimal" in the sense of being optimal for one criterion and optimal or near-optimal for the other two criteria. Comparisons with previo... View full abstract»

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  • A class of binoid single-error-correcting codes (Corresp.)

    Publication Year: 1975, Page(s):468 - 469
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (567 KB)

    A new class of group binoid single-error-correcting codes is given. The codes are nonbinary group codes over the additive group of integers modulo<tex>q</tex>. View full abstract»

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  • Convergence of distortion for block coding of symmetric modular sources (Corresp.)

    Publication Year: 1975, Page(s):469 - 472
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1213 KB)

    We define a symmetric modular source to be a source-user pair consisting of an equiprobable discrete memoryless source together with a modular context-dependent fidelity criterion. For this source-user pair we establish the existence of block codes of fixed rateRgreater thanR(D)with average distortion that decreases towardsDat a doubly exponential rate in block len... View full abstract»

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  • Estimation and detection of signals in multiplicative noise (Corresp.)

    Publication Year: 1975, Page(s):472 - 474
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (923 KB)

    We consider a class of matrix signal processes that are received in the presence of multiplicative observation noise. By examining the differential version of the observation, we are able to derive finite-dimensional optimal detection-estimation equations that involve a linear filter with gain computed on-line using the incoming observations. An example involving the detection of an actuator failu... View full abstract»

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  • System error bounds for Lagrange polynomial estimation of band-limited functions (Corresp.)

    Publication Year: 1975, Page(s):474 - 476
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (865 KB)

    Several recent articles [1]-[3] have discussed the use of Lagrange polynomials for band-limited signal estimation. We find error bounds when using Lagrange polynomials for interpolation and extrapolation of finite-power band-limited signals if a finite number of regularly spaced noisy samples are used. View full abstract»

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  • Autoregressive model fitting with noisy data by Akaike's information criterion (Corresp.)

    Publication Year: 1975, Page(s):476 - 480
    Cited by:  Papers (44)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1432 KB)

    Davisson [131, [141 has considered the problem of determining the "order" of the signal from noisy data. Although interesting theoretically, his result is difficult to use in practice. In this correspondence, we exploit one well-known fact concerning autoregressive (AR) signals plus white noise, and using Akaike's information criterion [15], [17], we have developed one efficient procedure for dete... 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