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Information Theory, IEEE Transactions on

Issue 4 • Date July 1969

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Displaying Results 1 - 19 of 19
  • Review of 'Algebraic Coding Theory' (Berlekamp, E. R.; 1968)

    Page(s): 509 - 510
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    Freely Available from IEEE
  • Review of 'Principles of Data Communication' (Lucky, R. W., et al; 1968)

    Page(s): 510
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    Freely Available from IEEE
  • An adaptive receiver for digital signaling through channels with intersymbol interference

    Page(s): 484 - 497
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    A tutorial paper on an adaptive receiver that is suitable for high-speed digital signaling over slowly time-varying, band-limited channels which have impulse responses that are unknown at the receiver is presented. The receiver utilizes a steepest-descent technique for adjusting its parameters to existing channel conditions. A treatment of the speed of adaptation of the receiver is included. View full abstract»

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  • Approximating discrete probability distributions

    Page(s): 444 - 447
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    The method of minimum discrimination information estimation is applied to the problem of estimating an n -dimensional discrete probability distribution in terms of lower order marginal distributions. The procedure provides a convergent iterative algorithm. The method yields regular best asymptotically normal (RBAN) estimates. The general procedure includes as a particular case that proposed by a method using dependence trees. An example is given. View full abstract»

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  • Conjugate linear filtering

    Page(s): 462 - 465
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    Aspects of optimum filtering for complex valued random processes are presented. Ordinary linear filters are complemented with conjugate linear filters. It is found that the incorporation of conjugate linear filtering improves signal-to-noise ratio by a factor of two in matched filter receivers. For optimum least squares filtering the inclusion of conjugate processing reduces mean-square error by a factor as great as two; the improvement depends primarily on the degree of correlation between the real and imaginary parts of the signal process. The analysis utilizes special correlation properties of receiver noise. Also, in the absence of phase lock, conjugate linear processing offers no improvement. Finally, it is observed that in the Gaussian case the least squares nonlinear receiver for modulations consists of the derived linear-conjugate linear receiver followed by demodulators comparable to those used in practice. View full abstract»

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  • Information rates for photocount detection systems

    Page(s): 465 - 468
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    A model that allows one to calculate information rates for optical communication systems that use photocount detection is presented. This model has its basis in the coherent states of the field. It consists of a source that places the field in a coherent state, a channel that can introduce additive Gaussian noise, and a photodetector that produces the number of photocounts in the detection interval as output symbols. The capability of introducing additive Gaussian noise can also be used to represent a physical source. The model is applied to several examples to illustrate its use. The rate of flow of information through the channel is calculated for a binary channel with and without additive Gaussian noise. The information rate for a noiseless channel is also obtained for the case in which the signals sent by a single-mode coherent source are selected from a Gaussian distribution. View full abstract»

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  • The correlation function of Gaussian noise passed through nonlinear devices

    Page(s): 448 - 456
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    This paper is concerned with the output autocorrelation function R^{y} of Gaussian noise passed through a nonlinear device. An attempt is made to investigate in a systematic way the changes in R^{y} when certain mathematical manipulations are performed on some given device whose correlation function is known. These manipulations are the "elementary combinations and transformations" used in the theory of Fourier integrals, such as addition, differentiation, integration, shifting, etc. To each of these, the corresponding law governing R^{y} is established. The same laws are shown to hold for the envelope of signal plus noise for narrow-band noise with spectrum symmetric about signal frequency. Throughout the text and in the Appendix it is shown how the results can be used to establish unknown correlation function quickly with main emphasis on power-law devices y = x^{m} with m either an integer or half integer. Some interesting recurrence formulas are given. A second-order differential equation is derived which serves as an alternative means for calculating R^{y} . View full abstract»

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  • Measurement of random time-variant linear channels

    Page(s): 469 - 475
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    This paper concerns the problems of the measurability and measurement of random time-variant linear channels. With regard to measurability, a new, less stringent channel measurability criterion is proposed to supersede the BL product introduced by Kailath. This criterion involves the area of occupancy of the Doppler-delay spread function (or its dual). By using time and bandwidth constraints on the input and output of a channel, channel measurement is reduced to the measurement of a discrete set of finite parameters. Optimal measurement techniques are described and their performances determined for both known and unknown channel correlation functions. View full abstract»

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  • Reliability function of a band-limited signaling scheme with feedback (Corresp.)

    Page(s): 507 - 508
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    The performance of a band-limited signaling scheme for an additive white Gaussian noise channel with noiseless feedback is presented. View full abstract»

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  • Bounds for truncation error in sampling expansions of band-limited signals

    Page(s): 440 - 444
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    For f(t) a real-valued signal band-limited to - \pi r \leq \omega \leq \pi r (0 < r < 1) and represented by its Fourier integral, upper bounds are established for the magnitude of the truncation error when f(t) is approximated at a generic time t by an appropriate selection of N_{1} + N_{2} + 1 terms from its Shannon sampling series expansion, the latter expansion being associated with the full band [-\pi, \pi] and thus involving samples of f taken at the integer points. Results are presented for two cases: 1) the Fourier transform F(\omega ) is such that |F(\omega )|^{2} is integrable on [-\pi, \pi r] (finite energy case), and 2) |F(\omega )| is integrable on [-\pi r, \pi r] . In case 1) it is shown that the truncation error magnitude is bounded above by g(r, t) \cdot \sqrt {E} \cdot \left( frac{1}{N_{1}} + frac{1}{N_{2}} \right) where E denotes the signal energy and g is independent of N_{1}, N_{2} and the particular band-limited signal being approximated. Correspondingly, in case 2) the error is bounded above by h(r, t) \cdot M \cdot \left( frac{1}{N_{1}} + frac{1}{N_{2}} \right) where M is the maximum signal amplitude and h is independent of N_{1}, N_{2} and the signal. These estimates possess the same asymptotic behavior as those exhibited earlier by Yao and Thomas [2], but are derived here using only real variable methods in conjunction with the signal representation. In case 1), the estimate obtained represents a sharpening of the Yao-Thomas bound for values of r dose to unity. View full abstract»

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  • Optimal recursive estimation with uncertain observation

    Page(s): 457 - 462
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    In classical estimation theory, the observation is always assumed to contain the signal to be estimated. In practice, certain observations, or sequences of observations, may contain noise alone, only the probability of occurrence of such cases being available to the estimator. An example is trajectory tracking where the signal is first detected and then the estimator is allowed to process it for tracking purposes. However, any detection decision is associated with a false-alarm probability, which is the probability that the detected signal contains only noise. Minimum mean-square estimators are derived for two different forms of this problem; 1) when it is possible that the observation at any sample time contains signal or is noise alone, independent of the situation at any other sample, and 2) when the entire sequence of observations contains signal or is only noise. The estimators derived are of recursive form. A simple example is given for illustration. View full abstract»

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  • On the equivalence of Kramer's and Shannon's sampling theorems (Corresp.)

    Page(s): 497 - 499
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    The question of Campbell concerning the possibility of applying Shannon's sampling theorem to the same functions that can be sampled by Kramer's generalized sampling theorem is investigated and illustrated for more functions which are solutions of second-order differential equations with singular coefficients. A few definitions are introduced and some theorems are proved to show, in a more precise way, that under certain conditions the two sampling theorems are equivalent. View full abstract»

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  • Bayesian decision procedure for interfering digital signals (Corresp.)

    Page(s): 506 - 507
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    The Bayesian decision procedure is given to determine a finite sequence of n m -ary (m \geq 2) digits that have been transmitted through a channel that has memory and introduces additive noise. Minimum probability of digit estimation error is used as the criterion of goodness. Intersymbol interference at the receiver input is assumed to exist between L successive digits. The parameter n is chosen so that n \gg L . This procedure is compared with several suboptimal procedures that are used to combat intersymbol interference and additive noise. View full abstract»

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  • Feedback communication using orthogonal signals

    Page(s): 478 - 483
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    We consider a feedback communication system in which the forward and feedback channels are disturbed by additive noise and constrained in average power. Two block coding schemes are proposed in which the signals are orthogonal waveforms. A finite number of forward and feedback transmissions per message is made. Information received over the feedback channel is used to reduce the expected value of forward signal energy on all iterations after the first. Similarly, the expected value of feedback signal energy is reduced on all iterations after the first. These schemes, which are modifications of a feedback coding scheme due to Kramer, obtain improved error performance over one-way coding at all rates up to the forward channel capacity, provided only that the feedback channel capacity is greater than the forward channel capacity. They require less feedback power than existing feedback coding schemes to achieve a given error performance. View full abstract»

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  • The efficiency of level tests in the detection of weak stochastic signals (Corresp.)

    Page(s): 502 - 504
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    The efficiency of a class of test statistics for the detection of a stochastic signal in Gaussian and non-Gaussian white noise is examined. The tests are computationaUy simple, but not distribution free. In Gaussian noise these tests surpass two commonly used detection procedures. View full abstract»

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  • On a general relationship between estimation, detection, and the Bhattacharyya coefficient (Corresp.)

    Page(s): 504 - 505
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    A general and fundamental relationship between estimation, detection/pattern recognition, and the Bhattacharyya coefficient is established. Specifically, it is shown that a functional of the likelihood ratio necessary for Bayes optimal detection/pattern recognition is the Bayes-optimal mean-square estimate of the indicator variable \beta , where \beta = 1, 0 , for hypotheses H_{1}, H_{0} , respectively. The Bhattacharyya coefficient is then shown to be the expected value of the estimation error standard deviation. View full abstract»

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  • Binary communication over the Gaussian channel using feedback with a peak energy constraint

    Page(s): 476 - 478
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    We consider binary communication over the additive white Gaussian noise channel with no bandwidth constraint on the channel input signals, assuming the availability of a noiseless delayless feedback link. Although the signals at time t can depend on the noise at times \tau < t and are therefore random functions, we require that the signal energy never exceed a fixed level. We show that the optimal probability of error is attainable without the use of the feedback channel by using antipodal signals. 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