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IEEE Transactions on Information Theory

Issue 6 • Nov. 1994

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Displaying Results 1 - 25 of 40
  • Rotationally invariant nonlinear trellis codes for two-dimensional modulation

    Publication Year: 1994, Page(s):1773 - 1791
    Cited by:  Papers (15)  |  Patents (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1616 KB)

    A general parity-check equation is presented that defines rotationally invariant trellis codes of rate k/(k+1) for two-dimensional signal sets. This parity-check equation is used to find rate k/(k+1) codes for 4PSK, 8PSK, 16PSK, and QAM signal sets by systematic code searches. The MPSK codes exhibit smaller free Euclidean distances than nonrotationally invariant linear codes with the same number o... View full abstract»

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  • Erasure-free sequential decoding of trellis codes

    Publication Year: 1994, Page(s):1803 - 1817
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1418 KB)

    An erasure-free sequential decoding algorithm for trellis codes, called the buffer looking algorithm (BLA), is introduced. Several versions of the algorithm can be obtained by choosing certain parameters and selecting a resynchronization scheme. These can be categorized as block decoding or continuous decoding, depending on the resynchronization scheme. Block decoding is guaranteed to resynchroniz... View full abstract»

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  • Density/length profiles and trellis complexity of lattices

    Publication Year: 1994, Page(s):1753 - 1772
    Cited by:  Papers (29)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1492 KB)

    The density/length profile (DCP) of a lattice Λ is analogous to the dimension/length profile of a linear code. The DLP is a geometrical invariant of Λ that includes the coding gain of Λ. Duality results analogous to those of linear block codes are derived for lattices. Bounds on the DLP may be derived from bounds on Hermite's constants; these hold with equality for many dense ... View full abstract»

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  • Asymptotic results on codes for symmetric, unidirectional, and asymmetric error control

    Publication Year: 1994, Page(s):2073 - 2075
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (252 KB)

    The asymptotic behavior of the rates of optimal codes correcting and/or detecting combinations of symmetric, unidirectional, and/or asymmetric errors is studied. These rates are expressed in terms of the rate of optimal codes,,with a certain Hamming distance. As a consequence, well-known bounds on the latter rate can also be applied to bound the former rates. Furthermore, it turns out that, withou... View full abstract»

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  • Shaping of multidimensional signal constellations using a lookup table

    Publication Year: 1994, Page(s):2058 - 2062
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (432 KB)

    This paper describes a lookup table for the addressing of an optimally shaped constellation. The method is based on partitioning the subconstellations into shaping macro-shells of integer bit rate and increasing average energy. The macro-shells do not need to have an equal number of points. A lookup table is used to select a subset of the partitions in the cartesian product space. By devising appr... View full abstract»

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  • Dimension/length profiles and trellis complexity of linear block codes

    Publication Year: 1994, Page(s):1741 - 1752
    Cited by:  Papers (143)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (888 KB)

    This semi-tutorial paper discusses the connections between the dimension/length profile (DLP) of a linear code, which is essentially the same as its “generalized Hamming weight hierarchy”, and the complexity of its minimal trellis diagram. These connections are close and deep. DLP duality is closely related to trellis duality. The DLP of a code gives tight bounds on its state and branc... View full abstract»

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  • Construction of fixed-length insertion/deletion correcting runlength-limited codes

    Publication Year: 1994, Page(s):1841 - 1856
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1220 KB)

    An algorithm is presented for the construction of fixed-length insertion/deletion correcting runlength-limited (RLL) codes. In this construction binary (d,k)-constrained codewords are generated by codewords of a q-ary Lee metric based code. It is shown that this new construction always yields better codes than known constructions. The use of a q-ary Lee (1987) metric code (q odd) is based on the a... View full abstract»

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  • An upper bound on the volume of discrete spheres

    Publication Year: 1994, Page(s):2071 - 2073
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (260 KB)

    Finite-length sequences over a finite alphabet with weights are considered. An information-theoretic upper bound on the number of such sequences whose weight does not exceed some given threshold is presented View full abstract»

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  • A differential equation approach to the computation of the Fourier transform of the images of translating objects

    Publication Year: 1994, Page(s):2049 - 2058
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (664 KB)

    The frequency domain analysis of constant velocity motion has proven useful in a number of different contexts ranging from television signal processing to computer vision. This work considers the frequency domain analysis of a generalization of such simple dynamics, which includes the effect of acceleration and its time derivatives (of any order). In the frequency domain the contribution due to th... View full abstract»

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  • Superimposed codes in the Hamming space

    Publication Year: 1994, Page(s):1882 - 1893
    Cited by:  Papers (3)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (876 KB)

    We consider the problem of simultaneous identification and transmission of information by means of superimposed codes. It is assumed that a total population of T users share a common channel. At each time at most in of the T users are active. The output from the channel is the modulo-2 sum of the binary codewords transmitted by the active users, possibly disturbed by errors. A superimposed code is... View full abstract»

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  • Rates of convergence in the source coding theorem, in empirical quantizer design, and in universal lossy source coding

    Publication Year: 1994, Page(s):1728 - 1740
    Cited by:  Papers (54)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1040 KB)

    Rate of convergence results are established for vector quantization. Convergence rates are given for an increasing vector dimension and/or an increasing training set size. In particular, the following results are shown for memoryless real-valued sources with bounded support at transmission rate R. (1) If a vector quantizer with fixed dimension k is designed to minimize the empirical mean-square er... View full abstract»

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  • High-order spectral-null codes-constructions and bounds

    Publication Year: 1994, Page(s):1826 - 1840
    Cited by:  Papers (34)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1120 KB)

    Let 𝒮(n.k) denote the set of all words of length n over the alphabet {+1,-1}, having a k th order spectral-null at zero frequency. A subset of 𝒮(n,k) is a spectral-null code of length n and order k. Upper and lower bounds on the cardinality of 𝒮(n,k) are derived. In particular we prove that (k-1) log2 (n/k)⩽n-log2 |𝒮(n,k)|⩽O(2klog... View full abstract»

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  • A communication channel modeled on contagion

    Publication Year: 1994, Page(s):2035 - 2041
    Cited by:  Papers (37)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (616 KB)

    We introduce a binary additive communication channel with memory. The noise process of the channel is generated according to the contagion model of G. Polya (1923); our motivation is the empirical observation of Stapper et al. (1980) that defects in semiconductor memories are well described by distributions derived from Polya's urn scheme. The resulting channel is stationary but not ergodic, and i... View full abstract»

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  • A generalized DFT for Abelian codes over Zm

    Publication Year: 1994, Page(s):2082 - 2090
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (736 KB)

    A generalized discrete Fourier transform defined over an appropriate extension ring is given that is suitable to characterize Abelian codes over residue class integer rings Zm. The characterization is in terms of generalized discrete Fourier transform components taking values from certain ideals of the extension ring. It is shown that the results known for cyclic codes over Z... View full abstract»

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  • Weight distributions of some binary primitive cyclic codes

    Publication Year: 1994, Page(s):2068 - 2071
    Cited by:  Papers (12)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    Let s and k be integers such that s is a divisor of 2k-1. Let g(x) be a divisor of xs-1 over F2 , and let π(x) be a primitive polynomial of degree k over F2. We consider the binary cyclic code C of length N=2k -1 generated by (XN-1)/g(x)π(x). For special cases, we determine the weight distribution of C by using the weights of ... View full abstract»

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  • Variance of a generalized polarity-coincidence spectral-centroid estimator for Gaussian processes

    Publication Year: 1994, Page(s):2045 - 2048
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (432 KB)

    The polarity coincidence estimator of the spectral centroid counts the net number of times the phasor of a stationary Gaussian process crosses a chosen phase-reference straight line through the origin during a time T. By following Pawula's (1968) approach, the covariance of two different simultaneous polarity-coincidence estimates having distinct phase reference lines is derived. This basic result... View full abstract»

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  • A mapping approach to rate-distortion computation and analysis

    Publication Year: 1994, Page(s):1939 - 1952
    Cited by:  Papers (58)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1136 KB)

    In rate-distortion theory, results are often derived and stated in terms of the optimizing density over the reproduction space. In this paper, the problem is reformulated in terms of the optimal mapping from the unit interval with Lebesgue measure that would induce the desired reproduction probability density. This results in optimality conditions that are “random relatives” of the kno... View full abstract»

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  • Intersecting codes and independent families

    Publication Year: 1994, Page(s):1872 - 1881
    Cited by:  Papers (35)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (848 KB)

    A binary intersecting code is a linear code with the property that any two nonzero codewords have intersecting supports. These codes appear in a wide variety of contexts and applications, e.g., multiple access, cryptography, and information theory. This paper is devoted partly to the study of intersecting codes, and partly to their use in constructing large t-independent families of binary vectors... View full abstract»

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  • Shannon-theoretic approach to a Gaussian cellular multiple-access channel

    Publication Year: 1994, Page(s):1713 - 1727
    Cited by:  Papers (442)  |  Patents (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (960 KB)

    We obtain Shannon-theoretic limits for a very simple cellular multiple-access system. In our model the received signal at a given cell site is the sum of the signals transmitted from within that cell plus a factor α (0⩽α⩽1) times the sum of the signals transmitted from the adjacent cells plus ambient Gaussian noise. Although this simple model is scarcely realistic, it neverthel... View full abstract»

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  • Variable-rate source coding theorems for stationary nonergodic sources

    Publication Year: 1994, Page(s):1920 - 1925
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (412 KB)

    For a stationary ergodic source, the source coding theorem and its converse imply that the optimal performance theoretically achievable by a fixed-rate or variable-rate block quantizer is equal to the distortion-rate function, which is defined as the infimum of an expected distortion subject to a mutual information constraint. For a stationary nonergodic source, however, the. Distortion-rate funct... View full abstract»

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  • Quickest detection of an abrupt change in a random sequence with finite change-time

    Publication Year: 1994, Page(s):1985 - 1993
    Cited by:  Papers (6)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (700 KB)

    This paper proposes a new procedure for quickest detection of an abrupt change in a random sequence, where a change is known to occur with probability one. Applications include on-line speech segmentation, edge detection in image processing, and communications channel monitoring. In contrast to Shiryayev's (1963) problem formulation, prior knowledge of a change-time distribution is not required. T... View full abstract»

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  • Minimal presentations for irreducible sofic shifts

    Publication Year: 1994, Page(s):1818 - 1825
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (724 KB)

    We re-cast a theorem of Willems (1989) in terms of symbolic dynamics. We then present a new result which characterizes when an irreducible sofic shift (i.e., constrained system) has a unique minimal irreducible presentation View full abstract»

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  • Rate-distortion function when side-information may be present at the decoder

    Publication Year: 1994, Page(s):2031 - 2034
    Cited by:  Papers (60)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    A discrete memoryless source {Xk} is to be coded into a binary stream of rate R bits/symbol such that {Xk} can be recovered with minimum possible distortion. The system is to be optimized for best performance with two decoders, one of which has access to side-information about the source. For given levels of average distortion for these two decoders, the minimum achievable ra... View full abstract»

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  • A bounded-distance decoding algorithm for lattices obtained from a generalized code formula

    Publication Year: 1994, Page(s):2075 - 2082
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (588 KB)

    A multistage decoding algorithm is given for lattices obtained from a multilevel code formula. The algorithm is shown to have the same effective error-correcting radius as maximum-likelihood decoding, so that the performance loss is essentially determined by the increase in the effective error coefficient, for which an expression is given. The code formula generalizes some previous multilevel cons... View full abstract»

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  • On communication complexity of vector-valued functions

    Publication Year: 1994, Page(s):2062 - 2067
    Cited by:  Papers (19)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (484 KB)

    New upper and lower bounds on the two-way communication complexity of abstract functions g:ℋ×𝒴→𝒵 give tight bounds, when applied to vector-valued functions fn(f1 ,...,fn):ℋu×𝒴n →𝒵n, if the alphabets are small. For the set-intersection function, an optimal protocol is presented. It ... 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