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Information Theory, IEEE Transactions on

Issue 8 • Date Aug. 2004

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Displaying Results 1 - 25 of 35
  • Table of contents

    Publication Year: 2004 , Page(s): c1 - c4
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    Freely Available from IEEE
  • IEEE Transactions on Information Theory publication information

    Publication Year: 2004 , Page(s): c2
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  • Second-order asymptotics of mutual information

    Publication Year: 2004 , Page(s): 1567 - 1580
    Cited by:  Papers (50)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (360 KB) |  | HTML iconHTML  

    A formula for the second-order expansion of the input-output mutual information of multidimensional channels as the signal-to-noise ratio (SNR) goes to zero is obtained. While the additive noise is assumed to be Gaussian, we deal with very general classes of input and channel distributions. As special cases, these channel models include fading channels, channels with random parameters, and channel... View full abstract»

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  • A conditional entropy power inequality for dependent variables

    Publication Year: 2004 , Page(s): 1581 - 1583
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    We provide a condition under which a version of Shannon's entropy power inequality will hold for dependent variables. We first provide a Fisher information inequality extending that found in the independent case. The key ingredients are a conditional expectation representation for the score function of a sum, and the de Bruijn identity which relates entropy and Fisher information. View full abstract»

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  • Network vector quantization

    Publication Year: 2004 , Page(s): 1584 - 1604
    Cited by:  Papers (35)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (672 KB) |  | HTML iconHTML  

    We present an algorithm for designing locally optimal vector quantizers for general networks. We discuss the algorithm's implementation and compare the performance of the resulting "network vector quantizers" to traditional vector quantizers (VQs) and to rate-distortion (R-D) bounds where available. While some special cases of network codes (e.g., multiresolution (MR) and multiple description (MD)... View full abstract»

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  • Suboptimality of the Karhunen-Loeve transform for transform coding

    Publication Year: 2004 , Page(s): 1605 - 1619
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    We examine the performance of the Karhunen-Loeve transform (KLT) for transform coding applications. The KLT has long been viewed as the best available block transform for a system that orthogonally transforms a vector source, scalar quantizes the components of the transformed vector using optimal bit allocation, and then inverse transforms the vector. This paper treats fixed-rate and variable-rate... View full abstract»

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  • Universal lossless coding for sources with repeating statistics

    Publication Year: 2004 , Page(s): 1620 - 1635
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    A lower bound is derived on the achievable redundancy for universal lossless coding of parametric sources with piecewise stationary, abruptly changing, occasionally repeating statistics. In particular, it is shown that if the number of repeating statistical parameter vectors (or states) is not too large, for any uniquely decipherable code, for almost every set of states that govern all the differe... View full abstract»

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  • On successive refinement for the Wyner-Ziv problem

    Publication Year: 2004 , Page(s): 1636 - 1654
    Cited by:  Papers (80)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (464 KB) |  | HTML iconHTML  

    Achievable rates are characterized for successive refinement (SR) in the Wyner-Ziv scenario, namely, in the presence of correlated side information (SI) at the receivers. In this setting, the encoder is assumed to operate in two stages, where the first corresponds to relatively low rate and high distortion, and the second, comprising a refinement code on top of the first code, is aimed at reproduc... View full abstract»

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  • Asymptotic improvement of the Gilbert-Varshamov bound on the size of binary codes

    Publication Year: 2004 , Page(s): 1655 - 1664
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    Given positive integers n and d, let A2(n,d) denote the maximum size of a binary code of length n and minimum distance d. The well-known Gilbert-Varshamov bound asserts that A2(n,d)≥2n/V(n,d-l), where V(n,d) = σi=0d(in) is the volume of a Hamming sphere of radius d. We show that, in fact, there exists a positive ... View full abstract»

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  • Gaussian codes and weighted nearest neighbor decoding in fading multiple-antenna channels

    Publication Year: 2004 , Page(s): 1665 - 1686
    Cited by:  Papers (29)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (496 KB) |  | HTML iconHTML  

    We investigate the fading multiple-antenna channel. The decoder is assumed to possess imperfect channel fading information. A modified nearest neighbor decoder with an innovative weighting factor is introduced and an expression for the generalized mutual information (GMI), the achievable rate, is obtained. We show that under certain conditions the achievable rate is equivalent to that of a fading ... View full abstract»

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  • Construction of linear codes with large minimum distance

    Publication Year: 2004 , Page(s): 1687 - 1691
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    A natural goal in coding theory is to find a linear [n, k;q]-code such that the minimum distance d is maximal. In this paper, we introduce an algorithm to construct linear [n, k;q]-codes with a prescribed minimum distance d by constructing an equivalent structure, the so-called minihyper, which is a system of points in the (k - 1)-dimensional projective geometry Pk-1(q) over the finite ... View full abstract»

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  • A logarithmic upper bound on the minimum distance of turbo codes

    Publication Year: 2004 , Page(s): 1692 - 1710
    Cited by:  Papers (32)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (584 KB) |  | HTML iconHTML  

    We derive new upper bounds on the minimum distance, which turbo codes can maximally attain with the optimum interleaver of a given length. The new bounds grow approximately logarithmically with the interleaver length, and they are tighter than all previously derived bounds for medium-length and long interleavers. An extensive discussion highlights the impacts of the new bounds in the context of in... View full abstract»

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  • Design methods for irregular repeat-accumulate codes

    Publication Year: 2004 , Page(s): 1711 - 1727
    Cited by:  Papers (53)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (512 KB) |  | HTML iconHTML  

    We optimize the random-like ensemble of irregular repeat-accumulate (IRA) codes for binary-input symmetric channels in the large block-length limit. Our optimization technique is based on approximating the evolution of the densities (DE) of the messages exchanged by the belief-propagation (BP) message-passing decoder by a one-dimensional dynamical system. In this way, the code ensemble optimizatio... View full abstract»

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  • Cyclic and negacyclic codes over finite chain rings

    Publication Year: 2004 , Page(s): 1728 - 1744
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (608 KB) |  | HTML iconHTML  

    The structures of cyclic and negacyclic codes of length n and their duals over a finite chain ring R are established when n is not divisible by the characteristic of the residue field R~. Some cases where n is divisible by the characteristic of the residue field R~ are also considered. Namely, the structure of negacyclic codes of length 2t over Z2m and that of thei... View full abstract»

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  • A class of 1-generator quasi-cyclic codes

    Publication Year: 2004 , Page(s): 1745 - 1753
    Cited by:  Papers (15)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (264 KB) |  | HTML iconHTML  

    If R = Fq[x]/(xm - 1), S = Fqn[x]/(xm - 1), we define the mapping a_(x) → A(x) =σ0n-1ai(x)αi from Rn onto S, where (α0, αi,..., αn-1) is a basis for Fqn over F... View full abstract»

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  • Multiple-input multiple-output sampling: necessary density conditions

    Publication Year: 2004 , Page(s): 1754 - 1768
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (400 KB) |  | HTML iconHTML  

    We consider the problem of multiple-input multiple-output (MIMO) sampling of multiband signals. In this problem, a set of input signals is passed through a MIMO channel modeled as a known linear time-invariant system. The inputs are modeled as multiband signals whose spectral supports are sets of finite measure and the channel outputs are sampled on nonuniform sampling sets. The aim is to reconstr... View full abstract»

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  • On the capacity loss due to separation of detection and decoding

    Publication Year: 2004 , Page(s): 1769 - 1778
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (408 KB) |  | HTML iconHTML  

    The performance loss due to separation of detection and decoding on the binary-input additive white Gaussian noise (AWGN) channel is quantified in terms of mutual information. Results are reported for both the code-division multiple-access (CDMA) channel in the large system limit and the intersymbol interference (ISI) channel. The results for CDMA rely on the replica method developed in statistica... View full abstract»

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  • On skew information

    Publication Year: 2004 , Page(s): 1778 - 1782
    Cited by:  Papers (28)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (168 KB) |  | HTML iconHTML  

    In this paper, we show that skew information introduced by Wigner and Yanase, which is a natural informational extension of variance for pure states, can be interpreted as a measure of quantum uncertainty. By virtue of skew information, we establish a new uncertainty relation in the spirit of Schrodinger, which incorporates both incompatibility (encoded in the commutator) and correlations (encoded... View full abstract»

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  • Generalization of Shannon-Khinchin axioms to nonextensive systems and the uniqueness theorem for the nonextensive entropy

    Publication Year: 2004 , Page(s): 1783 - 1787
    Cited by:  Papers (19)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    Tsallis entropy, one-parameter generalization of Shannon entropy, has been often discussed in statistical physics as a new information measure. This new information measure has provided many satisfactory physical interpretations in nonextensive systems exhibiting chaos or fractal. We present the generalized Shannon-Khinchin axioms to nonextensive systems and prove the uniqueness theorem rigorously... View full abstract»

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  • Quasicyclic low-density parity-check codes from circulant permutation matrices

    Publication Year: 2004 , Page(s): 1788 - 1793
    Cited by:  Papers (372)  |  Patents (66)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    In this correspondence, the construction of low-density parity-check (LDPC) codes from circulant permutation matrices is investigated. It is shown that such codes cannot have a Tanner graph representation with girth larger than 12, and a relatively mild necessary and sufficient condition for the code to have a girth of 6, 8,10, or 12 is derived. These results suggest that families of LDPC codes wi... View full abstract»

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  • On existence of good self-dual quasicyclic codes

    Publication Year: 2004 , Page(s): 1794 - 1798
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (240 KB) |  | HTML iconHTML  

    For a long time, asymptotically good self-dual codes have been known to exist. Asymptotically good 2-quasicyclic codes of rate 1/2 have also been known to exist for a long time. Recently, it was proved that there are binary self-dual n/3-quasicyclic codes of length n asymptotically meeting the Gilbert-Varshamov bound. Unlike 2-quasicyclic codes, which are defined to have a cyclic group of order n/... View full abstract»

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  • Self-dual codes and modules for finite groups in characteristic two

    Publication Year: 2004 , Page(s): 1798 - 1803
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    Using representation theoretical methods we investigate self-dual group codes and their extensions in characteristic 2. We prove that the existence of a self-dual extended group code heavily depends on a particular structure of the group algebra KG which can be checked by an easy-to-handle criteria in elementary number theory. Surprisingly, in the binary case such a code is doubly even if the conv... View full abstract»

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  • On the complexity of multicovering radii

    Publication Year: 2004 , Page(s): 1804 - 1808
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (232 KB) |  | HTML iconHTML  

    The multicovering radius is a generalization of the covering radius. In this correspondence, we show that lower-bounding the m-covering radius of an arbitrary binary code is NP-complete when m is polynomial in the length of the code. Lower-bounding the m-covering radius of a linear code is Σ2P-complete when m is polynomial in the length of the code. If P is not equal to... View full abstract»

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  • On error exponents for woven convolutional codes with one tailbiting component code

    Publication Year: 2004 , Page(s): 1809 - 1812
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (144 KB) |  | HTML iconHTML  

    An error exponent for woven convolutional codes (WCC) with one tailbiting component code is derived. This error exponent is compared with that of the original WCC. It is shown that for WCC with outer warp, a better error exponent is obtained if the inner code is terminated with the tailbiting method. Furthermore, it is shown that the decoding error probability decreases exponentially with the squa... View full abstract»

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  • Simple MAP decoding of first-order Reed-Muller and Hamming codes

    Publication Year: 2004 , Page(s): 1812 - 1818
    Cited by:  Papers (19)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (352 KB) |  | HTML iconHTML  

    A maximum a posteriori (MAP) probability decoder of a block code minimizes the probability of error for each transmitted symbol separately. The standard way of implementing MAP decoding of a linear code is the Bahl-Cocke-Jelinek-Raviv (BCJR) algorithm, which is based on a trellis representation of the code. The complexity of the BCJR algorithm for the first-order Reed-Muller (RM-1) codes and Hammi... 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