IEEE Transactions on Information Theory

Volume 45 Issue 1 • Jan. 1999

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Displaying Results 1 - 25 of 41
  • Minimal syndrome formers for group codes

    Publication Year: 1999, Page(s):3 - 31
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1760 KB)

    Given a controllable group code, it has been shown by Forney (1970, 1973), Trott, and Loeliger (1994) that it is possible to construct a canonical encoder whose state space coincides with the canonical state space of the code, that is the essential element determining the minimal trellis of the code. The construction of such an encoder is based on the concept of controllability granule. In this pa... View full abstract»

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  • Type II codes over F/sub 2/+uF/sub 2/

    Publication Year: 1999, Page(s):32 - 45
    Cited by:  Papers (72)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (606 KB)

    The alphabet F/sub 2/+uF/sub 2/ is viewed here as a quotient of the Gaussian integers by the ideal (2). Self-dual F/sub 2/+uF/sub 2/ codes with Lee weights a multiple of 4 are called Type II. They give even unimodular Gaussian lattices by Construction A, while Type I codes yield unimodular Gaussian lattices. Construction B makes it possible to realize the Leech lattice as a Gaussian lattice. There... View full abstract»

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  • On lowest density MDS codes

    Publication Year: 1999, Page(s):46 - 59
    Cited by:  Papers (108)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (765 KB)

    Let F/sub q/ denote the finite field GF(q) and let h be a positive integer. MDS (maximum distance separable) codes over the symbol alphabet F/sub q//sup b/ are considered that are linear over F/sub q/ and have sparse ("low-density") parity-check and generator matrices over F/sub q/ that are systematic over F/sub q//sup b/. Lower bounds are presented on the number of nonzero elements in any systema... View full abstract»

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  • Structural analysis of error-correcting codes for discrete channels that involve combinations of three basic error types

    Publication Year: 1999, Page(s):60 - 77
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (1344 KB)

    A nonprobabilistic mathematical model is introduced of discrete channels that involve the error types substitution, insertion, and deletion. The model is based on the novelty that errors can be expressed as strings over an alphabet of basic error symbols. Some general conditions on errors are defined which bound the error effects on messages, obtaining thus the class of bounded error effects chann... View full abstract»

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  • Composite scheme LR+Th for decoding with erasures and its effective equivalence to Forney's rule

    Publication Year: 1999, Page(s):78 - 93
    Cited by:  Papers (17)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (907 KB)

    For decoding with erasures, Forney's scheme is known to be optimal in the sense that no other scheme can make the erasure probability P/sub ers/ and undetected error probability P/sub uer/ simultaneously smaller. We propose a scheme for erasure decision which tests the likelihood ratio as well as the likelihood itself and show that the attainable upper bounds on P/sub ers/ and P/sub uer/ are the s... View full abstract»

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  • Interpolation by convolutional codes, overload distortion, and the erasure channel

    Publication Year: 1999, Page(s):94 - 105
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (450 KB)

    This paper investigates how closely randomly generated binary source sequences can be matched by convolutional code codewords. What distinguishes it from prior work is that a randomly chosen subsequence with density /spl lambda/ is to be matched as closely as possible. The so-called marked bits of the subsequence could indicate overload quantization points for a source sample generated from the ta... View full abstract»

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  • Multiterminal source coding with high resolution

    Publication Year: 1999, Page(s):106 - 117
    Cited by:  Papers (69)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    We consider separate encoding and joint decoding of correlated continuous information sources, subject to a difference distortion measure. We first derive a multiterminal extension of the Shannon lower bound for the rate region. Then we show that this Shannon outer bound is asymptotically tight for small distortions. These results imply that the loss in the sum of the coding rates due to the separ... View full abstract»

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  • Entropy bounds for constrained two-dimensional random fields

    Publication Year: 1999, Page(s):118 - 127
    Cited by:  Papers (35)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (464 KB)

    The maximum entropy and thereby the capacity of two-dimensional (2-D) fields given by certain constraints on configurations is considered. Upper and lower bounds are derived. A new class of 2-D processes yielding good lower bounds is introduced. Asymptotically, the process achieves capacity for constraints with limited long-range effects. The processes are general and may also be applied to, e.g.,... View full abstract»

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  • State learning and mixing in entropy of hidden Markov processes and the Gilbert-Elliott channel

    Publication Year: 1999, Page(s):128 - 138
    Cited by:  Papers (18)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (561 KB)

    Hidden Markov processes such as the Gilbert-Elliott (1960) channel have an infinite dependency structure. Therefore, entropy and channel capacity calculations require knowledge of the infinite past. In practice, such calculations are often approximated with a finite past. It is commonly assumed that the approximations require an unbounded amount of the past as the memory in the underlying Markov c... View full abstract»

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  • Capacity of a mobile multiple-antenna communication link in Rayleigh flat fading

    Publication Year: 1999, Page(s):139 - 157
    Cited by:  Papers (872)  |  Patents (31)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (945 KB)

    We analyze a mobile wireless link comprising M transmitter and N receiver antennas operating in a Rayleigh flat-fading environment. The propagation coefficients between pairs of transmitter and receiver antennas are statistically independent and unknown; they remain constant for a coherence interval of T symbol periods, after which they change to new independent values which they maintain for anot... View full abstract»

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  • Distributed detection for diversity reception of fading signals in noise

    Publication Year: 1999, Page(s):158 - 164
    Cited by:  Papers (38)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (317 KB)

    A multiple-antenna diversity scheme is investigated for digital communications. Antenna observations are immediately quantized and sent to a fusion center. At the fusion center, the quantized observations are combined to form a final decision on which symbol was transmitted. The optimum reception scheme is described for the case where frequency-shift keying is employed and where slow Rayleigh fadi... View full abstract»

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  • Asymptotic normality of the posterior in relative entropy

    Publication Year: 1999, Page(s):165 - 176
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (739 KB)

    We show that the relative entropy between a posterior density formed from a smooth likelihood and prior and a limiting normal form tends to zero in the independent and identically distributed case. The mode of convergence is in probability and in mean. Applications to code lengths in stochastic complexity and to sample size selection are discussed. View full abstract»

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  • Asymptotic distributions for the performance analysis of hypothesis testing of isolated-point-penalization point processes

    Publication Year: 1999, Page(s):177 - 187
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (408 KB)

    The performance of the likelihood ratio test is considered for a many-point interaction point process featuring a reduced number of isolated points. Limit theorems are proved that establish the Poissonian asymptotic distribution of the log-likelihood function for point processes with the isolated-point-penalization joint probability density function. The asymptotic distribution is used to approxim... View full abstract»

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  • On the security of iterated message authentication codes

    Publication Year: 1999, Page(s):188 - 199
    Cited by:  Papers (26)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (325 KB)

    The security of iterated message authentication code (MAC) algorithms is considered, and in particular, those constructed from unkeyed hash functions. A new MAC forgery attack applicable to all deterministic iterated MAC algorithms is presented, which requires on the order of 2/sup n/2/ known text-MAC pairs for algorithms with n bits of internal memory, as compared to the best previous general att... View full abstract»

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  • Robust vector quantization by a linear mapping of a block code

    Publication Year: 1999, Page(s):200 - 218
    Cited by:  Papers (19)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (540 KB)

    In this paper we propose a novel technique for vector quantizer design where the reconstruction vectors are given by a linear mapping of a binary block code (LMBC). The LMBC framework provides a relation between the index bits and the reconstruction vectors through mapping properties. We define a framework, show its flexibility, and give optimality conditions. We consider source optimized vector q... View full abstract»

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  • Decision feedback multiuser detection: a systematic approach

    Publication Year: 1999, Page(s):219 - 240
    Cited by:  Papers (130)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (830 KB)

    A systematic approach to decision feedback multiuser detection is introduced for the joint detection of symbols of K simultaneously transmitting users of a synchronous correlated waveform multiple-access (CWMA) channel with Gaussian noise. A new performance criterion called symmetric energy is defined which is a low-noise indicator of the joint error rate that at least one user is detected erroneo... View full abstract»

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  • Error-event characterization on partial-response channels

    Publication Year: 1999, Page(s):241 - 247
    Cited by:  Papers (33)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (304 KB)

    Two algorithms for characterization of input error events producing specified distance at the output of certain binary-input partial-response (PR) channels are presented. Lists of error events are tabulated for PR channels of interest in digital recording. View full abstract»

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  • On the distance distribution of duals of BCH codes

    Publication Year: 1999, Page(s):247 - 250
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (169 KB)

    We derive upper bounds on the components of the distance distribution of duals of BCH codes. Roughly speaking, these bounds show that the distance distribution can be upper-bounded by the corresponding normal distribution. To derive the bounds we use the linear programming approach along with some estimates on the magnitude of Krawtchouk polynomials of fixed degree in a vicinity of q/2. View full abstract»

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  • More on the distance distribution of BCH codes

    Publication Year: 1999, Page(s):251 - 255
    Cited by:  Papers (11)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (234 KB)

    We derive a new estimate for the error term in the binomial approximation to the distance distribution of BCH codes. This is an improvement on the earlier bounds by Kasami-Fujiwara-Lin (1985), Vladuts-Skorobogatov (1991), and Krasikov-Litsyn (1995). View full abstract»

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  • Finding short and light codewords in BCH codes

    Publication Year: 1999, Page(s):255 - 260
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (228 KB)

    A new algorithm is presented for finding codewords that are of low weight ("light") and low degree ("short") in narrow-sense binary BCH codes of length n=2/sup m/-1 and minimum weight d=2/sup t/-1, for use in serial implementations. This improves on some earlier results by Roth and Scroussi (see ibid., vol.34, p.593-6, May 1998), and extends the range of parameters to include cases of interest for... View full abstract»

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  • Efficient Forney functions for decoding AG codes

    Publication Year: 1999, Page(s):260 - 265
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (262 KB)

    Using a Forney formula to solve for the error magnitudes in decoding algebraic-geometric (AG) codes requires producing functions /spl sigma//sub P/, which are 0 at all but one point P of the variety of the error-locator ideal. The best such function is produced here in a reasonably efficient way from a lex Grobner basis. This lex basis is, in turn, produced efficiently from a weighted grevlex basi... View full abstract»

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  • Quantum codes of minimum distance two

    Publication Year: 1999, Page(s):266 - 271
    Cited by:  Papers (25)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (233 KB)

    It is reasonable to expect the theory of quantum codes to be simplified in the case of codes of minimum distance 2; thus it makes sense to examine such codes in the hopes that techniques that prove effective there will generalize. With this in mind, we present a number of results on codes of minimum distance 2. We first compute the linear programming bound on the dimension of such a code, then sho... View full abstract»

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  • X-code: MDS array codes with optimal encoding

    Publication Year: 1999, Page(s):272 - 276
    Cited by:  Papers (189)  |  Patents (11)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (178 KB)

    We present a new class of MDS (maximum distance separable) array codes of size n/spl times/n (n a prime number) called X-code. The X-codes are of minimum column distance 3, namely, they can correct either one column error or two column erasures. The key novelty in X-code is that it has a simple geometrical construction which achieves encoding/update optimal complexity, i.e., a change of any single... View full abstract»

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  • Weight hierarchies of extremal non-chain binary codes of dimension 4

    Publication Year: 1999, Page(s):276 - 281
    Cited by:  Papers (6)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (275 KB)

    The weight hierarchy of a linear [n,k;q] code C over GF(q) is the sequence (d/sub 1/,d/sub 2/,/spl middot//spl middot//spl middot/,d/sub k/) where d/sub r/ is the smallest support of an r-dimensional subcode of C. An [n,k;q] code is extremal nonchain if, for any r and s, where 1/spl les/r<s/spl les/k, there are no subspaces D and E such that D/spl sub/E, dim D=r, dim E=s,w/sub S/(D)=d/sub r/, a... View full abstract»

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  • The minimum distance of the [137,69] binary quadratic residue code

    Publication Year: 1999
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (49 KB)

    We find that the minimum distance of the binary [137,69] quadratic residue code is 21. 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.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Alexander Barg

Department of Electrical and Computer Engineering and the Institute for Systems Research, University of Maryland

email: abarg-ittrans@ece.umd.edu