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IEEE Transactions on Information Theory

Issue 2 • Date March 1996

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Displaying Results 1 - 25 of 37
  • Algebraic Function Fields and Codes [Book Reviews]

    Publication Year: 1996
    Request permission for commercial reuse | PDF file iconPDF (402 KB)
    Freely Available from IEEE
  • Unveiling turbo codes: some results on parallel concatenated coding schemes

    Publication Year: 1996, Page(s):409 - 428
    Cited by:  Papers (695)  |  Patents (57)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1516 KB)

    A parallel concatenated coding scheme consists of two simple constituent systematic encoders linked by an interleaver. The input bits to the first encoder are scrambled by the interleaver before entering the second encoder. The codeword of the parallel concatenated code consists of the input bits to the first encoder followed by the parity check bits of both encoders. This construction can be gene... View full abstract»

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  • Location-correcting codes

    Publication Year: 1996, Page(s):554 - 565
    Cited by:  Papers (7)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1144 KB)

    We study codes over GF(q) that can correct t channel errors assuming the error values are known. This is a counterpart to the well-known problem of erasure correction, where error values are found assuming the locations are known. The correction capabilities of these so-called t-location correcting codes (t-LCCs) are characterized by a new metric, the decomposability distance, which plays a role a... View full abstract»

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  • An upper bound on the distribution of computation of a sequential decoder for multiple-access channels

    Publication Year: 1996, Page(s):399 - 408
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (584 KB)

    The computational distribution of sequential decoding for discrete memoryless multiple-access channels is examined. It is shown that all possible collections of incorrect paths in the code tree may be described by bipartite graphs. Using this fact and a new decoding metric it is proved that the number of computations in the first incorrect subtree is a Paretean random variable, and that the parame... View full abstract»

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  • On punctured trellis-coded modulation

    Publication Year: 1996, Page(s):627 - 636
    Cited by:  Papers (9)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (924 KB)

    Punctured convolutional codes result in some savings in the complexity of Viterbi decoders, compared to other codes of the same rate. However, in general use of the punctured structure in the decoder results in a performance loss for trellis codes, due to difficulties in assigning metrics, We provide constructions for punctured rate-2/3 codes based on decomposition of the metric into orthogonal co... View full abstract»

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  • Generation of canonical M-sequences and dual bases

    Publication Year: 1996, Page(s):638 - 641
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (316 KB)

    An expression for the shift necessary to obtain a canonical M-sequence is obtained in terms of the coefficients of the primitive polynomial that generates this m-sequence. This shift for obtaining a canonical M-sequence is also directly related to the shift for obtaining the location of the span “100...0” in the M-sequence. In addition, a recursion is developed for obtaining the dual b... View full abstract»

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  • Time discretization of continuous-time filters and smoothers for HMM parameter estimation

    Publication Year: 1996, Page(s):593 - 605
    Cited by:  Papers (31)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (980 KB)

    In this paper we propose algorithms for parameter estimation of fast-sampled homogeneous Markov chains observed in white Gaussian noise. Our algorithms are obtained by the robust discretization of stochastic differential equations involved in the estimation of continuous-time hidden Markov models (HMM's) via the EM algorithm. We present two algorithms: the first is based on the robust discretizati... View full abstract»

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  • Iterative decoding of binary block and convolutional codes

    Publication Year: 1996, Page(s):429 - 445
    Cited by:  Papers (1249)  |  Patents (196)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1420 KB)

    Iterative decoding of two-dimensional systematic convolutional codes has been termed “turbo” (de)coding. Using log-likelihood algebra, we show that any decoder can be used which accepts soft inputs-including a priori values-and delivers soft outputs that can be split into three terms: the soft channel and a priori inputs, and the extrinsic value. The extrinsic value is used as an a pri... View full abstract»

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  • On the cardinality of systematic authentication codes via error-correcting codes

    Publication Year: 1996, Page(s):566 - 578
    Cited by:  Papers (8)  |  Patents (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1084 KB)

    In both open and private communication the participants face potential threats from a malicious enemy who has access to the communication channel and can insert messages (impersonation attack) or alter already transmitted messages (substitution attack). Authentication codes (A-codes) have been developed to provide protection against these threats. In this paper we introduce a new distance, called ... View full abstract»

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  • Nearly optimal multiuser codes for the binary adder channel

    Publication Year: 1996, Page(s):387 - 398
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1028 KB)

    Coding schemes for the T-user binary adder channel are investigated. Recursive constructions are given for two families of mixed-rate, multiuser codes. It is shown that these basic codes can be combined by time-sharing to yield codes approaching most rates in the T-user capacity region. In particular, the best codes constructed herein achieve a sum-rate, R1+...+RT, which is h... View full abstract»

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  • Generation of matrices for determining minimum distance and decoding of cyclic codes

    Publication Year: 1996, Page(s):653 - 657
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    A simple method based on Newton's identities and their extensions is presented for determining the actual minimum distance of cyclic codes. More significantly, it is shown that this method also provides a mechanism for generating the type of syndrome matrices needed by Feng and Tzeng's (see ibid., vol.40, p.1364-1374, Sept. 1994) new procedure for decoding cyclic and BCH codes up to their actual m... View full abstract»

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  • The ternary Golay code, the integers mod 9, and the Coxeter-Todd lattice

    Publication Year: 1996, Page(s):636 - 637
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (208 KB)

    The 12-dimensional Coxeter-Todd lattice can be obtained by lifting the ternary Golay code to a code over the integers mod 9 and applying Construction A View full abstract»

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  • Hashing of databases based on indirect observations of Hamming distances

    Publication Year: 1996, Page(s):664 - 671
    Cited by:  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (696 KB)

    We describe hashing of databases as a problem of information and coding theory. It is shown that the triangle inequality for the Hamming distances between binary vectors may essentially decrease the computational efforts of a search for a pattern in a database. Introduction of the Lee distance in the space, which consists of the Hamming distances, leads to a new metric space where the triangle ine... View full abstract»

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  • Weight enumerators of extremal singly-even [60,30,12] codes

    Publication Year: 1996, Page(s):658 - 659
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (168 KB)

    Conway and Sloane (1990) have listed the possible weight enumerators for extremal self-dual codes up to length 72. In this correspondence, we construct extremal singly-even self-dual [60,30,12] codes whose weight enumerator does not appear in this list. In addition, we present the possible weight enumerators for extremal self-dual codes of length 60 View full abstract»

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  • Asymptotic distribution of the errors in scalar and vector quantizers

    Publication Year: 1996, Page(s):446 - 460
    Cited by:  Papers (25)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1268 KB)

    High-rate (or asymptotic) quantization theory has found formulas for the average squared length (more generally, the qth moment of the length) of the error produced by various scalar and vector quantizers with many quantization points. In contrast, this paper finds an asymptotic formula for the probability density of the length of the error and, in certain special cases, for the probability densit... View full abstract»

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  • On the asymptotic distribution of the errors in vector quantization

    Publication Year: 1996, Page(s):461 - 468
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (616 KB)

    In a recent paper, Lee and Neuhoff (see ibid., vol.42, no.2, p446-60, 1996) found an asymptotic formula for the distribution of the length of the errors produced by a vector quantizer with many quantization points. This distribution depends on the source probability density, the quantizer point density, and the quantizer shape profile. (The latter characterizes the shapes of the quantization cells... View full abstract»

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  • Group codes generated by finite reflection groups

    Publication Year: 1996, Page(s):519 - 528
    Cited by:  Papers (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (916 KB)

    Slepian-type group codes generated by finite Coxeter groups are considered. The resulting class of group codes is a generalization of the well-known permutation modulation codes of Slepian (1965), it is shown that a restricted initial-point problem for these codes has a canonical solution that can easily be computed. This allows one to enumerate all optimal group codes in this restricted sense and... View full abstract»

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  • Classification with finite memory

    Publication Year: 1996, Page(s):337 - 347
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (760 KB)

    Consider the following situation. A device called a classifier observes a probability law P on l-vectors from an alphabet of size A. Its task is to observe a second probability law Q and decide whether P≡Q or P and Q are sufficiently different according to some appropriate criterion. If the classifier has available an unlimited memory (so that it can remember P(z) exactly for all z), this is... View full abstract»

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  • The effect of decision delay in finite-length decision feedback equalization

    Publication Year: 1996, Page(s):618 - 621
    Cited by:  Papers (55)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (352 KB)

    In this correspondence we derive the finite-length, minimum mean-squared error decision feedback equalizer (MMSE-DFE). We include decision delay as an explicit parameter. Our derivation yields an algebraic interpretation of the effect of decision delay on DFE performance (measured by mean-squared error). It also allows the fast computation of the MMSE-DFE for several different values of both decis... View full abstract»

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  • On the cost of finite block length in quantizing unbounded memoryless sources

    Publication Year: 1996, Page(s):480 - 487
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (656 KB)

    The problem of fixed-rate block quantization of an unbounded real memoryless source is studied. It is proved that if the source has a finite sixth moment, then there exists a sequence of quantizers Qn of increasing dimension n and fixed rate R such that the mean squared distortion Δ(Qn) is bounded as Δ(Qn )⩽D(R)+O(√(log n/n)), where D(R) is t... View full abstract»

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  • Irregular sampling for spline wavelet subspaces

    Publication Year: 1996, Page(s):623 - 627
    Cited by:  Papers (25)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (332 KB)

    Spline wavelets ψm(t) are important in time-frequency localization due to (i) ψm can be arbitrarily close to the optimal case as m is sufficiently large, (ii) ψm has compact support and simple analytic expression, which lead to effective computation. Although the spline wavelet subspaces are so simple, Walter's well-known sampling theorem does not hold ... View full abstract»

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  • Universal portfolios with side information

    Publication Year: 1996, Page(s):348 - 363
    Cited by:  Papers (56)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1228 KB)

    We present a sequential investment algorithm, the μ-weighted universal portfolio with side information, which achieves, to first order in the exponent, the same wealth as the best side-information dependent investment strategy (the best state-constant rebalanced portfolio) determined in hindsight from observed market and side-information outcomes. This is an individual sequence result which sho... View full abstract»

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  • A soft-output decoding algorithm for concatenated systems

    Publication Year: 1996, Page(s):543 - 553
    Cited by:  Papers (15)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1016 KB)

    In order to fully utilize the SDD (soft-decision decoding) capacity of the outer codes in a concatenated system, reliability information on the inner decoder outputs (called soft outputs) needs to be provided to the outer decoder. This paper shows that a modified MAP algorithm can be effectively and accurately used to generate such information. In the course of the presentation, a metric based on ... View full abstract»

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  • Large families of quaternary sequences with low correlation

    Publication Year: 1996, Page(s):579 - 592
    Cited by:  Papers (64)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (764 KB)

    A family of quaternary (Z4-alphabet) sequences of length L=2r-1, size M⩾L2+3L+2, and maximum nontrivial correlation parameter Cmax⩽2√(L+1)+1 is presented. The sequence family always contains the four-phase family 𝒜. When r is odd, it includes the family of binary Gold sequences. The sequence family is easily generated using two shift r... View full abstract»

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  • On generalizations of repeated-root cyclic codes

    Publication Year: 1996, Page(s):641 - 649
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (768 KB)

    We first consider repeated-root cyclic codes, i.e., cyclic codes whose block length is divisible by the characteristic of the underlying field. It is well known that the formula for the minimum distance of repeated-root cyclic codes is similar to that for generalized concatenated codes. We show that indecomposable repeated-root cyclic codes are product codes and that the minimum weight of each rep... 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
Frank R. Kschischang

Department of Electrical and Computer Engineering