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IEEE Transactions on Information Theory

Volume 36 Issue 4 • Jul 1990

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Displaying Results 1 - 25 of 34
  • The structure and design of realizable decision feedback equalizers for IIR channels with colored noise

    Publication Year: 1990, Page(s):848 - 858
    Cited by:  Papers (23)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (824 KB)

    A simple algorithm for optimizing decision feedback equalizers (DFEs) by minimizing the mean-square error (MSE) is presented. A complex baseband channel and correct past decisions are assumed. The dispersive channel may have infinite impulse response, and the noise may be colored. Consideration is given to optimal realizable (stable and finite-lag smoothing) forward and feedback filters in discret... View full abstract»

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  • Comments on "On the covering radius of codes" [with reply]

    Publication Year: 1990, Page(s):953 - 954
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (185 KB)

    The commenters point out that with the definition of the norm of a code as originally given in the above-titled paper (see ibid., vol.IT 31, p.385-401, May 1985), certain results do not hold. However, with the corrected definition given by G.D. Cohen et al. (see ibid., vol.IT 32, p.680-94, Sept. 1986), they do hold. they also point out that the hypotheses of Lemma 27 of the above-titled paper need... View full abstract»

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  • On the quadratic spans of DeBruijn sequences

    Publication Year: 1990, Page(s):822 - 829
    Cited by:  Papers (15)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (596 KB)

    The quadratic span of a periodic binary sequence is defined to be the length of the shortest quadratic feedback shift register (FSR) that generates it. An algorithm for computing the quadratic span of a binary sequence is described. The required increase in quadratic span is determined for the special case of when a discrepancy occurs in a linear FSR that generates an initial portion of a sequence... View full abstract»

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  • Variable-to-fixed length codes are better than fixed-to-variable length codes for Markov sources

    Publication Year: 1990, Page(s):861 - 863
    Cited by:  Papers (13)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (180 KB)

    It is demonstrated that for finite-alphabet, kth-order ergodic Markov sources (i.e. memory of k letters), a variable-to-fixed length code is better than the best fixed-to-variable length code (Huffman code). It is shown how to construct a variable-to-fixed length code for a kth order ergodic Markov source, which compresses more effectively than the best fixed-to-variable... View full abstract»

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  • Pseudocyclic maximum-distance-separable codes

    Publication Year: 1990, Page(s):880 - 884
    Cited by:  Papers (39)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (432 KB)

    The (n, k) pseudocyclic maximum-distance-separable (MDS) codes modulo (xn- a) over GF(q) are considered. Suppose that n is a divisor of q+1. If n is odd, pseudocyclic MDS codes exist for all k. However, if n is even, nontrivial pseudocyclic MDS codes exist for odd k (but not for even k... View full abstract»

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  • On the minimum distance of combinatorial codes

    Publication Year: 1990, Page(s):922 - 923
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (120 KB)

    A conjecture of V.C. Da Rocha (see Electron. Lett., vol.21, no.21, p.949-50, 1985) concerning the minimum distance of a class of combinatorial codes is proved View full abstract»

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  • ϵ-entropy and critical distortion of random fields

    Publication Year: 1990, Page(s):717 - 725
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (520 KB)

    The link between ε-entropy for binary random fields and the Lee-Yang theorem in statistical mechanics makes it possible to prove the existence of positive critical distortion for most binary random fields with pair interactions and some with many body interactions. Lower bounds for critical distortion of random fields on two-dimensional (2-D) lattices have been obtained. In particular, the ne... View full abstract»

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  • On decoding unequal error protection product codes

    Publication Year: 1990, Page(s):890 - 895
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    The decoding of unequal error protection product codes, which are a combination of linear unequal error protection (UEP) codes and product codes, is addressed. A nonconstructive proof of the existence of a good error-erasure-decoding algorithm is presented; however, obtaining the decoding procedure is still an open research problem. A particular subclass of UEP product codes is considered, includi... View full abstract»

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  • Fixed-prefix encoding of the integers can be Huffman-optimal

    Publication Year: 1990, Page(s):936 - 938
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (272 KB)

    Various source coding schemes encode the set of integers using a binary representation of the integers to be encoded, prefixed by some information about the length of that representation. In the context of recency rank encoding, these can be regarded as attempts to assign codewords with lengths close to the logarithm of the integer to be encoded, or as attempts to construct a code for a distributi... View full abstract»

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  • Vector coding for partial response channels

    Publication Year: 1990, Page(s):741 - 762
    Cited by:  Papers (133)  |  Patents (29)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1608 KB)

    A linear technique for combining equalization and coset codes on partial response channels with additive white Gaussian noise is developed. The technique, vector coding, uses a set of transmit filters or `vectors' to partition the channel into an independent set of parallel intersymbol interference (ISI)-free channels for any given finite (or infinite) block length. The optimal transmit vectors fo... View full abstract»

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  • The hardness of solving subset sum with preprocessing

    Publication Year: 1990, Page(s):943 - 946
    Cited by:  Papers (21)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    The two problems subset sum and linear decoding (which have given birth to the knapsack and the McEliece public-key cryptosystems) are known to be NP-complete. For linear decoding, it has been proved that, even if one knows the linear code in advance and can preprocess it, the existence of a polynomial-time decoding algorithm would imply that the polynomial-time hierarchy collapses at an early sta... View full abstract»

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  • Focused codes for channels with skewed errors

    Publication Year: 1990, Page(s):773 - 783
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (776 KB)

    Consider a channel with inputs and outputs in the field F q(q>2). It is said that the channel is skewed on a set B⊂Fq* if the additive noise generated by the channel is likely to lie in B, i.e. B is a set of common errors. The concern is the construction of focused codes that are appropriate for such channels. It is... View full abstract»

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  • An asymptotically optimal random modem and detector for robust communication

    Publication Year: 1990, Page(s):810 - 821
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (868 KB)

    Coherent communication over a waveform channel corrupted by thermal noise and by an unknown and arbitrary interfering signal of bounded power is considered. For a fixed encoder, a random modulator/demodulator (modem) and detector are derived. They asymptotically minimize the worst-case error probability as the blocklength of the encoder becomes large. This optimal modem is independent of the encod... View full abstract»

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  • A Karhunen-Loeve-like expansion for 1/f processes via wavelets

    Publication Year: 1990, Page(s):859 - 861
    Cited by:  Papers (176)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (220 KB)

    While so-called 1/f or scaling processes emerge regularly in modeling a wide range of natural phenomena, as yet no entirely satisfactory framework has been described for the analysis of such processes. Orthonormal wavelet bases are used to provide a new construction for nearly 1/f processes from a set of uncorrelated random variables View full abstract»

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  • Algebraic decoding of the (32, 16, 8) quadratic residue code

    Publication Year: 1990, Page(s):876 - 880
    Cited by:  Papers (44)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (396 KB)

    An algebraic decoding algorithm for the 1/2-rate (32, 16, 8) quadratic residue (QR) code is found. The key idea of this algorithm is to find the error locator polynomial by a systematic use of the Newton identities associated with the code syndromes. The techniques developed extend the algebraic decoding algorithm found recently for the (32, 16, 8) QR code. It is expected that the algebraic approa... View full abstract»

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  • The nonexistence of certain binary linear codes

    Publication Year: 1990, Page(s):917 - 922
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (452 KB)

    Some of the upper bounds given by T. Verhoeff (1987) are improved by proving the nonexistence of codes with certain parameters. Necessary preliminary results are stated. The results give rise to upper bounds on d(n, k) for many further values of (n, k) by using simple standard techniques. The further bounds would automatically follow from theorems by us... View full abstract»

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  • Cross spectral analysis of nonstationary processes

    Publication Year: 1990, Page(s):830 - 835
    Cited by:  Papers (56)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    Consideration is given to the generalization of stationary cross spectral analysis methods to a class of nonstationary processes, specifically, the class of semistationary finite energy processes possessing sample functions that are of finite energy almost surely. A new quantity called the time-frequency coherence (TFC) is defined, and it is demonstrated that its properties are analogous to those ... View full abstract»

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  • A limit theorem for n-phase Barker sequences

    Publication Year: 1990, Page(s):863 - 868
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (264 KB)

    It is proved that for 3⩽L⩽19, except for L =6, the total number of normalized n-phase Barker sequences of length L increases without limit as n goes to infinity View full abstract»

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  • Decoder malfunction in BCH decoders

    Publication Year: 1990, Page(s):884 - 889
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (540 KB)

    A t-error-correcting bounded-distance decoder either produces the codeword nearest the received vector (if there is a codeword at distance no more than t) or indicates that no such codeword exists. However, BCH decoders based on the Peterson-Gorenstein-Zierler algorithm or the Euclidean algorithm can malfunction and produce output vectors that are not codewords at all. For any in... View full abstract»

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  • Computer search for binary cyclic UEP codes of odd length up to 65

    Publication Year: 1990, Page(s):924 - 935
    Cited by:  Papers (18)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (728 KB)

    Exhaustive computation by a computer was used to find the unequal error protection capabilities of all binary cyclic codes of odd length up to 65 that have minimum distances of at least 3. For those codes for which upper bounds can only be computed on their unequal error protection capabilities, an analytic method developed by V.N. Dynkin and V.A. Togonidze (1976) is used to show that the upper bo... View full abstract»

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  • Nonequiprobable signaling on the Gaussian channel

    Publication Year: 1990, Page(s):726 - 740
    Cited by:  Papers (112)  |  Patents (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1076 KB)

    Signaling schemes for the Gaussian channel based on finite-dimensional lattices are considered. The signal constellation consists of all lattice points within a region R, and the shape of this region determines the average signal power. Spherical signal constellations minimize average signal power, and in the limit as N →∞, the shape gain of the N-sphere over ... View full abstract»

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  • New lower bounds for covering codes

    Publication Year: 1990, Page(s):895 - 899
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    Some new lower bounds on |C| for a binary linear [n, k]R code C with n+1=t(R +1)-r(0⩽r<R+1, t>2 odd) or with n+1=t(R+1)-1(t>2 even) are obtained. These bounds improve the sphere covering bound considerably and give several new values and lower bounds f... View full abstract»

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  • A large deviations approach to error exponents in source coding and hypothesis testing

    Publication Year: 1990, Page(s):938 - 943
    Cited by:  Papers (16)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    It is pointed out that the basic results can be proved fairly easily if one uses a Sanov theorem for the distribution of types. Such a theorem comes easily from large deviation theory. A caveat is that this technique only identifies the error exponent up to terms o(n) in the exponent, whereas the combinatorial arguments give an estimate up to terms O(log n) in t... View full abstract»

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  • The method of poles: a coding method for constrained channels

    Publication Year: 1990, Page(s):763 - 772
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (732 KB)

    A method for solving coding problems involving channels restricted by finite state constraints is presented. The method was introduced by P.A. Franaszek (1969) and is based on the computation of a set of principal states. It is proved that state-independent decoding is guaranteed. The main result is that the transducer constructed using the method is a local automaton in its output. The method is ... View full abstract»

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  • Some comments on Zech's logarithms

    Publication Year: 1990, Page(s):946 - 950
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    Some properties of Zech's logarithms are stated and exploited to compute Zech's logarithms from a restricted set of key elements. Zech's logarithms are recommended for the fast solution of quadratic, cubic, and quartic equations over GF(2m) 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