IEEE Transactions on Information Theory

Volume 44 Issue 2 • Mar 1998

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Displaying Results 1 - 25 of 47
  • On the automorphism group of various Goppa codes

    Publication Year: 1998, Page(s):630 - 643
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (888 KB)

    We determine the automorphism group of various Goppa codes 𝒞 L(D,G) associated with certain function fields F/F q of genus g>0. It is well known that, for deg D=n>2g+2, the automorphism group {AutD,G(F/Fq) can be embedded into Aut(𝒞L(D,G)) as a subgroup. We show that, under certain conditions on the divisors D... View full abstract»

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  • Some structural properties of convolutional codes over rings

    Publication Year: 1998, Page(s):839 - 845
    Cited by:  Papers (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    Convolutional codes over rings have been motivated by phase-modulated signals. Some structural properties of the generator matrices of such codes are presented. Successively stronger notions of the invertibility of generator matrices are studied, and a new condition for a convolutional code over a ring to be systematic is given and shown to be equivalent to a condition given by Massey and Mittelho... View full abstract»

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  • The category of linear codes

    Publication Year: 1998, Page(s):612 - 629
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (588 KB)

    Slepian (1960) introduced a structure theory for linear, binary codes and proved that every such code was uniquely the sum of indecomposable codes. He had hoped to produce a canonical form for the generator matrix of an indecomposable code so that he might read off the properties of the code from such a matrix, but such a program proved impossible. We here work over an arbitrary field and define a... View full abstract»

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  • Typical error pattern recovery of the Hopfield memory under error-tolerant conditions

    Publication Year: 1998, Page(s):861 - 865
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (220 KB)

    We lower-bound the error-correcting capabilities of the Hopfield (1982) network under error-tolerant conditions, given some distorted version of a fundamental memory with a random (typical) error pattern. Our main result is that for any sufficiently small α, and for any ρ<1/2, a Hopfield memory with n neurons can store αn fundamental memories, such that the following is satisfie... View full abstract»

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  • Systematic feed-forward convolutional encoders are better than other encoders with an M-algorithm decoder

    Publication Year: 1998, Page(s):831 - 838
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Consider nonbacktracking convolutional decoders that keep a fixed number of trellis survivors. It is shown that the error performance of these depends on the early part of the distance profile and on the number of survivors kept, and not on the free distance or the details of the code generators. Particularly, the encoder may be feedforward systematic without loss. Furthermore, this kind of encode... View full abstract»

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  • On a new class of codes for identifying vertices in graphs

    Publication Year: 1998, Page(s):599 - 611
    Cited by:  Papers (172)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (636 KB)

    We investigate a new class of codes for the optimal covering of vertices in an undirected graph G such that any vertex in G can be uniquely identified by examining the vertices that cover it. We define a ball of radius t centered on a vertex υ to be the set of vertices in G that are at distance at most t from υ. The vertex υ is then said to cover itself and every other vertex in the... View full abstract»

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  • Asymptotic eigenvalue distribution of block-Toeplitz matrices

    Publication Year: 1998, Page(s):858 - 861
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (152 KB)

    The need for approximating block-Toeplitz with Toeplitz block matrices by means of block-circulant with circulant block matrices with the objective of transforming an inherently ill-posed image deconvolution problem to a well-posed one motivated a surge of papers on the analysis of the quality as well as the speed of convergence of the algorithms that produce such approximants to serve as precondi... View full abstract»

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  • The information-theoretic capacity of discrete-time queues

    Publication Year: 1998, Page(s):446 - 461
    Cited by:  Papers (50)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (780 KB)

    The information-theoretic capacity of continuous-time queues was analyzed recently by Anantharam and Verdu (see ibid. vol.42, p.4-18, 1996). Along similar lines, we analyze the information-theoretic capacity of two models of discrete-time queues. The first model has single packet arrivals and departures in a time slot and independent packet service times, and is the discrete-time analog of the con... View full abstract»

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  • A trellis-based recursive maximum-likelihood decoding algorithm for binary linear block codes

    Publication Year: 1998, Page(s):714 - 729
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (720 KB)

    This paper presents an efficient trellis-based maximum-likelihood decoding algorithm for binary linear block codes. This algorithm is recursive in nature and is devised based on the structural properties and optimum sectionalization of a code trellis. The complexity of the proposed decoding algorithm is analyzed. Numerical results show that the proposed decoding algorithm significantly reduces the... View full abstract»

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  • Limits to consistent on-line forecasting for ergodic time series

    Publication Year: 1998, Page(s):886 - 892
    Cited by:  Papers (31)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (312 KB)

    This article concerns problems of time-series forecasting under the weakest of assumptions. Related results are surveyed and are points of departure for the developments here, some of which are new and others are new derivations of previous findings. The contributions in this study are all negative, showing that various plausible prediction problems are unsolvable, or in other cases, are not solva... View full abstract»

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  • Achievable rates for Tomlinson-Harashima precoding

    Publication Year: 1998, Page(s):824 - 831
    Cited by:  Papers (66)  |  Patents (40)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (216 KB)

    This article examines Tomlinson-Harashima precoding (1971, 1972) on discrete-time channels having intersymbol interference and additive white Gaussian noise. An exact expression for the maximum achievable information rate of zero-forcing (ZF) THP is derived as a function of the channel impulse response, the input power constraint, and the additive white Gaussian noise variance. Information rate bo... View full abstract»

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  • Entropy/length profiles, bounds on the minimal covering of bipartite graphs, and trellis complexity of nonlinear codes

    Publication Year: 1998, Page(s):580 - 598
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    The trellis representation of nonlinear codes is studied from a new perspective. We introduce the new concept of entropy/length profile (ELP). This profile can be considered as an extension of the dimension/length profile (DLP) to nonlinear codes. This elaboration of the DLP, the entropy/length profiles, appears to be suitable to the analysis of nonlinear codes. Additionally and independently, we ... View full abstract»

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  • Exact recovery of higher order moments

    Publication Year: 1998, Page(s):851 - 858
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    This correspondence addresses the problem of exact recovery of higher order moments of unquantized signals from those of their quantized counterparts, in the context of nonsubtractive dithered quantization. It introduces a new statistical characterization of the dithered quantizer in the form of a pth-order moment-sense input/ouput function hp (x). A class of signals for which the solut... View full abstract»

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  • The context-tree weighting method: extensions

    Publication Year: 1998, Page(s):792 - 798
    Cited by:  Papers (52)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (328 KB)

    First we modify the basic (binary) context-tree weighting method such that the past symbols x1-D, x2-D, …, x 0 are not needed by the encoder and the decoder. Then we describe how to make the context-tree depth D infinite, which results in optimal redundancy behavior for all tree sources, while the number of records in the context tree is not larger than 2T-1... View full abstract»

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  • Bandwidth-efficient coded modulation with optimized linear partial-response signals

    Publication Year: 1998, Page(s):701 - 713
    Cited by:  Papers (35)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (344 KB)

    We study the design of optimal signals for bandwidth-efficient linear coded modulation. Previous results show that for linear channels with intersymbol interference (ISI), reduced-search decoding algorithms have near-maximum-likelihood error performance, but with much smaller complexity than the Viterbi decoder. Consequently, the controlled ISI introduced by a lowpass filter can be practically use... View full abstract»

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  • Some notes on Rissanen's stochastic complexity

    Publication Year: 1998, Page(s):782 - 786
    Cited by:  Papers (14)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (224 KB)

    A new version of stochastic complexity for a parametric statistical model is derived, based on a class of two-part codes. We show that choosing the quantization in the first step according to the Fisher information is optimal and we compare our approach to a recent result of Rissanen (1983). An application to robust regression model selection is presented View full abstract»

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  • Blind multiuser detection: a subspace approach

    Publication Year: 1998, Page(s):677 - 690
    Cited by:  Papers (558)  |  Patents (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (744 KB)

    A new multiuser detection scheme based on signal subspace estimation is proposed. It is shown that under this scheme, both the decorrelating detector and the linear minimum-mean-square-error (MMSE) detector can be obtained blindly, i.e., they can be estimated from the received signal with the prior knowledge of only the signature waveform and timing of the user of interest. The consistency and asy... View full abstract»

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  • The shape of low excursions of the envelope of a signal plus noise

    Publication Year: 1998, Page(s):882 - 886
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (200 KB)

    Like low excursions of the envelope of narrowband noise, those of the sum of a signal plus narrowband noise are hyperbolic in shape if the signal-to-noise ratio r is not high. When r≫1, low excursions of the envelope are hyperbolic if the signal is frequency-modulated but have a quartic shape with one or two minima if it is not. This article illuminates various aspects of FM clicks View full abstract»

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  • Some new extremal self-dual codes with lengths 44, 50, 54, and 58

    Publication Year: 1998, Page(s):809 - 812
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (196 KB)

    We construct extremal self-dual codes with lengths 44, 50, 54, and 58. They have weight enumerators for which extremal codes were previously not known to exist. Two methods are used for constructing the codes using self dual codes of same or smaller length. To obtain the codes we use a combinatorial optimization search View full abstract»

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  • Recent results on polyphase sequences

    Publication Year: 1998, Page(s):817 - 824
    Cited by:  Papers (22)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    A polyphase sequence of length n+1, A={aj}j=0n, is a sequence of complex numbers, each of unit magnitude. The (unnormalized) aperiodic autocorrelation function of a sequence is denoted by C(τ). Associated with the sequence A, the sequence polynomial fA(z) of degree n and the correlation polynomial gA(z) of degree 2n are defined. For each r... View full abstract»

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  • Asymptotic multiuser efficiencies for decision-directed multiuser detectors

    Publication Year: 1998, Page(s):502 - 515
    Cited by:  Papers (19)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (672 KB)

    The asymptotic multiuser efficiencies (AMEs) are derived for various classes of decision-directed multiuser detectors, including multistage detectors, and decision-feedback detectors. Novel classes of soft-decision multistage detectors are proposed and analyzed. Each class is specified in part by a soft-decision nonlinearity, such as a symmetric quantizer or a linear clipper. Closed-form expressio... View full abstract»

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  • A tight upper bound on discrete entropy

    Publication Year: 1998, Page(s):775 - 778
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (152 KB)

    The standard upper bound on discrete entropy was derived based on the differential entropy bound for continuous random variables. A tighter discrete entropy bound is derived using the transformation formula of Jacobi theta function. The new bound is applicable only when the probability mass function of the discrete random variable satisfies certain conditions. Its application to the class of binom... View full abstract»

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  • Systematic lossy source/channel coding

    Publication Year: 1998, Page(s):564 - 579
    Cited by:  Papers (160)  |  Patents (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (544 KB)

    The fundamental limits of “systematic” communication are analyzed. In systematic transmission, the decoder has access to a noisy version of the uncoded raw data (analog or digital). The coded version of the data is used to reduce the average reproduced distortion D below that provided by the uncoded systematic link and/or increase the rate of information transmission. Unlike the case o... View full abstract»

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  • Nonparametric estimation of transfer functions: rates of convergence and adaptation

    Publication Year: 1998, Page(s):644 - 658
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (868 KB)

    The paper deals with estimating the transfer functions of stable linear time-invariant systems under stochastic assumptions. We adopt a nonparametric minimax approach for measuring the estimation accuracy. The quality of an estimator is measured by its worst case error over a family of transfer functions. The families with polynomially and exponentially decaying impulse response sequences are cons... View full abstract»

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  • Efficient encoding algorithm for third-order spectral-null codes

    Publication Year: 1998, Page(s):846 - 851
    Cited by:  Papers (10)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (296 KB)

    An efficient algorithm is presented for encoding unconstrained information sequences into a third-order spectral-null code of length n and redundancy 9log2 n+O(log log n). The encoding can be implemented using O(n) integer additions and O(nlog n) counter increments View full abstract»

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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