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Information Theory, 1995. Proceedings., 1995 IEEE International Symposium on

Date 17-22 Sept. 1995

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Displaying Results 1 - 25 of 502
  • Proceedings of 1995 IEEE International Symposium on Information Theory

    Publication Year: 1995
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    Freely Available from IEEE
  • Cascaded convolutional codes

    Publication Year: 1995
    Cited by:  Papers (4)  |  Patents (1)
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    The construction and performance of cascaded convolutional codes is investigated. An interleaver is used between the inner and outer codes to redistribute errors out of the inner decoder. In addition, the structure of the interleaver is exploited to improve the distance properties of the overall cascaded code. This configuration is shown to have a performance advantage compared to a single complex convolutional code with the same rate and decoder complexity. View full abstract»

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  • Construction of trellis codes at high spectral efficiencies for use with sequential decoding

    Publication Year: 1995
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    Sequential decoding of trellis codes at high spectral efficiencies is investigated and large constraint length trellis codes for two dimensional and four dimensional constellations are constructed for use with sequential decoding. It is shown that the channel cut-off rate bound can be achieved using constraint lengths between 16 and 19 with sequential decoding at a bit error rate of 10/sup -5/-10/sup -6/. View full abstract»

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  • Author index

    Publication Year: 1995
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    Freely Available from IEEE
  • Universal estimation of the optimal probability distributions for data compression of discrete memoryless sources with fidelity criterion

    Publication Year: 1995
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    Output probability distributions of the test channels play important roles in data compression of discrete memoryless sources with fidelity criterion. In this paper a universal algorithm for estimating the output probability distributions is proposed. Sample size required by the algorithm is evaluated under a criterion of estimation similar to that of PAC learning in the computational learning theory View full abstract»

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  • Optimum distance profile trellis encoders for sequential decoding

    Publication Year: 1995
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    New trellis encoders over various lattice partitions having optimum distance profile (ODP) and large constraint lengths are constructed. They are attractive to use in combination with sequential decoding algorithms since their ODP property ensures good computational performance View full abstract»

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  • A universal data-base for data compression

    Publication Year: 1995
    Cited by:  Papers (1)
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    A database for data compression is universal if, in its construction no prior knowledge of the source distribution is assumed and is optimal if, when we encode the reference index of the database, its encoding rate achieves the optimal encoding rate for any given source: in the noiseless case the entropy rate and in the semifaithful case the rate-distortion function of the source. We construct a universal database for all stationary ergodic sources, and prove the optimality of the thus constructed database for a block-shift type reference and a single-shift type reference View full abstract»

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  • Error burst detection with high-rate convolutional codes

    Publication Year: 1995
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    One crucial requirement for the use of convolutional codes in (only) error detection is low decoding complexity. We show that for this specific application the decoding complexity of convolutional codes is practically equal to the coding complexity, which is very small. Thus, the encoder/decoder can be implemented directly in hardware, or use efficient software decoding techniques like those used for cyclic redundancy check (CRC) error detection codes. Different encoder/decoder implementations are considered. By studying the properties of high-rate convolutional codes for the purpose of error detection, we show their potential advantages over block codes. In addition, this study gives a deeper view of CRC codes-which happen to be a special case in a class of codes that we call unit-rate convolutional codes. Thus, for the extension of CRCs we can employ techniques used for convolutional codes, like the use of unit-memory or cyclic time-varying codes. Certain general error detection capabilities of the convolutional codes are derived View full abstract»

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  • A Bayes coding algorithm for FSM sources

    Publication Year: 1995
    Cited by:  Papers (2)  |  Patents (1)
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    The optimal universal code for FSMX sources (Rissanen 1981) with respect to Bayes redundancy criterion (Davison 1973) is deduced under the condition that the model, the probabilistic parameters and the initial state are unknown. The algorithm is not only Bayes optimal for FSMX sources but also asymptotically optimal for stationary ergodic sources. Moreover the algorithm is regarded as a generalisation of the Ziv-Lempel algorithm. In the basic CTW algorithm, the algorithm needs the initial context x1-dx2-d…x0 where: a finite constant d is the depth of the context tree, for calculating the coding probability of x1. For the problem of the initial situation and the infinite depth tree, the extensions to the CTW algorithm have been proposed in Willems (1994). The optimal algorithm proposed in the present paper gives a solution against these problems from another new point of view View full abstract»

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  • A class of iterative signal restoration algorithms

    Publication Year: 1995
    Cited by:  Papers (1)
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    Iterative methods have of late enjoyed increasing popularity in signal restoration problems. Inherent mathematical difficulties have led researchers to propose ad hoc solutions in many instances. The question of optimality of such solutions is an open one. This paper concerns this question for a class of iterative methods of signal restoration and offers a criterion for optimality based on information theory View full abstract»

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  • Balanced quadriphase sequences with near-ideal autocorrelations

    Publication Year: 1995
    Cited by:  Papers (1)
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    We describe a generalization of balanced binary sequences to quadriphase sequences. Given any prime p≡1 mod4 and any positive integer m, a class of balanced quadriphase sequences of length pm -1 with near-ideal periodic autocorrelation properties is constructed. The quadriphase sequences are optimal under the condition of balanced sequence elements View full abstract»

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  • Constellation shaping for the Gaussian channel

    Publication Year: 1995
    Cited by:  Patents (1)
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    Constellation shaping is method of improving the effectiveness of digital communications over noisy, bandlimited channels. We present a new view to the problem of constellation shaping. Both a new procedure and information theoretic analysis are discussed. The article presents an approach to understanding constellation shaping that avoids the “continuous approximation” analysis of performance. A unique “type-mapping” approach to shaping is derived and related to monomial orderings on a ring of polynomials. The basic methods of constellation shaping can be roughly characterized as forms of coset coding (i.e., codes for which messages are associated with cosets of a subgroup such as a linear subspace) and enumerative coding (i.e., codes for which messages are enumerations of vectors) View full abstract»

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  • A table-based reduced complexity sequential decoding algorithm

    Publication Year: 1995
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    The table-based soft-decision convolutional decoding method presented here performs a reduced tree search as compared to the M-algorithm. The degree of tree-searching is adapted to the state of the channel by using a syndrome sequence and pre-computed information stored in a memory table. This results in a significant reduction in computational complexity while maintaining bit error rate performance comparable to the M-algorithm on a Rayleigh flat-fading channel View full abstract»

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  • A CTW scheme for some FSM models

    Publication Year: 1995
    Cited by:  Papers (1)
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    The paper addresses a modified version of the CTW (context tree weighting) which deals with some FSM (finite state machine) models as well as the FSMX (FSM X) models at little expense of computing in encoding/decoding View full abstract»

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  • Threshold decoding of turbo-codes

    Publication Year: 1995
    Cited by:  Papers (8)  |  Patents (1)
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    The idea of iterative decoding of two-dimensional systematic convolutional codes-so-called turbo-codes-is extended to threshold decoding, which is presented in “soft-in/soft-out” form. The computational complexity of the proposed decoder is very low. Surprisingly good simulation results are shown for the Gaussian channel View full abstract»

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  • Stochastic processes and linear combinations of periodic clock changes

    Publication Year: 1995
    Cited by:  Papers (5)
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    Stochastic processes subjected to a periodic clock change function will have weighted versions of its power spectrum reproduced at integer multiples of the jitter frequency. It has been shown that the original process may, in theory, be reconstructed without error by a suitable choice of correction filter. We extend the results presented by Lacaze and Aakvaag (see ISIT'94) to the general case where the resulting process is a linear combination of N clock change functions View full abstract»

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  • Blind multiuser deconvolution in fading and dispersive channels

    Publication Year: 1995
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    An adaptive near-far resistant technique for the blind joint multiuser identification and detection in asynchronous CDMA systems is analyzed in fading and dispersive GSM channels View full abstract»

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  • Partial classification of sequences with perfect auto-correlation and bent functions

    Publication Year: 1995
    Cited by:  Papers (3)
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    Complex valued sequences of length n are considered. A sequence is said to be a perfect sequence if all the out-of-phase periodic autocorrelation coefficients are equal to zero. A sequence is said to be a phase shift keyed (PSK) sequence if all the coordinates are on the unit circle. A sequence is said to be a polyphase sequence if all the coordinates are n'th roots of unity. For the case n is a power of a prime integer, the partial classification of perfect PSK sequences is given. As a consequence, the full classification of one dimensional bent functions is presented View full abstract»

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  • Phase-shifted linear partial-response modulation

    Publication Year: 1995
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    Partial-response modulations are widely used for spectrum shaping and bandwidth reduction. Linear partial-response signaling (PRS) is a well-known form of linear coded modulation which was proposed by Lender (1963). Due to the lack of efficient algorithms for maximum likelihood detection the research on the subject concentrated on the simplest forms of PRS, and mainly with suboptimal detection. We analyze the properties of PRS signals generated from complex-valued functions. Those signals have not only the usual intentional intersymbol interference (ISI), but also an intentional interference between the quadrature components of the RF modulated signal. Our objective is to show how these two forms of interference should be used together. The theory presented is particularly important in the design of PRS generators for bandwidth efficient coded modulation, which are schemes with severe ISI. Furthermore, since the results are valid for intentional or non-intentional ISI, they can also be used to improve the performance of communications in non-ideal channels View full abstract»

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  • Upper bounds on the probability of the correct path loss for list decoding of fixed convolutional codes

    Publication Year: 1995
    Cited by:  Papers (2)
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    In list decoding (M-algorithm) the decoder state space is typically much smaller than the encoder state space. Hence, it can happen that the correct path is lost. This is a serious kind of error event that is typical for list decoding. In this paper two upper bounds on the probability of correct path loss for list decoding are given. For fixed convolutional codes counterparts to Viterbi's upper bounds for maximum-likelihood decoding of fixed convolutional codes are proved. Finally, it is shown that there exists a fixed convolutional code whose probability of correct path loss when decoded by list decoding satisfies a simple expurgated bound View full abstract»

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  • An asymptotic evaluation on the number of computation steps required for the nearest point search over a binary tree

    Publication Year: 1995
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    This paper analyzes the number of computation steps on a binary tree searching fast for one in some beforehand-given points (binary sequences) that is the nearest to a query point in a Hamming space View full abstract»

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  • Characterization of the Bayes estimator and the MDL estimator for exponential families

    Publication Year: 1995
    Cited by:  Papers (1)
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    We analyze the relationship between the MDL (minimum description length) estimator (posterior mode) and the PBE (projected Bayes estimator) for exponential families, where the PBE is obtained by projecting the BE (Bayes estimator, i.e. posterior mixture) onto the original exponential family and is equal to the BE under a certain condition View full abstract»

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  • On tree sources, finite state machines, and time reversal

    Publication Year: 1995
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    We investigate the effect of time reversal on tree models of finite-memory processes. This is motivated in part by the following simple question that arises in some data compression applications: when trying to compress a data string using a universal source modeler, can it make a difference whether we read the string from left to right or from right to left? We characterize the class of finite-memory two-sided tree processes, whose time-reversed versions also admit tree models. Given a tree model, we present a construction of the tree model corresponding to the reverse process, and we show that the number of states in the reverse tree might be, in the extreme case, quadratic in the number of states of the original tree. This answers the above motivating question in the affirmative View full abstract»

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  • An efficient reservation connection control protocol for gigabit networks

    Publication Year: 1995
    Cited by:  Papers (6)  |  Patents (1)
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    The efficient reservation virtual circuit (or ERVC) protocol is a novel connection control protocol designed for constant-rate delay-insensitive traffic in gigabit networks. In the ERVC protocol, session durations are recorded and capacity is reserved only for the duration of the session, starting at the time it is actually needed. The protocol also has the “reservation ahead” feature, which allows a node to calculate the time at which the requested capacity will be available and reserve it in advance, thus avoiding wasteful repetition of the call setup phase. In addition, the protocol is robust to link and node failures, and allows soft recovery from processor failures. The ERVC protocol is one of the two candidate protocols that we are considering for implementation in the 40 Gbit/s ATM-based fiber-optic Thunder and Lightning network currently being developed at UCSB View full abstract»

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  • Codes and iterative decoding on general graphs

    Publication Year: 1995
    Cited by:  Papers (21)  |  Patents (5)
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    Until recently, most known decoding procedures for error-correcting codes were based either on algebraically calculating the error pattern or on some sort of tree or trellis search. With the advent of turbo coding, a third decoding principle has finally had its breakthrough: iterative decoding. With respect to Viterbi decoding, a code is most naturally described by means of a trellis diagram. The main thesis of the present paper is that, with respect to iterative decoding, the natural way of describing a code is by means of a Tanner graph, which may be viewed as a generalized trellis. More precisely, it is the “time axis” of a trellis that is generalized to a Tanner graph View full abstract»

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