IEEE Transactions on Communications

Issue 8 • August 1978

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Displaying Results 1 - 25 of 34
  • [Front cover and table of contents]

    Publication Year: 1978, Page(s): 0
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    Freely Available from IEEE
  • Differential Pulse Code Modulation of Stationary Gaussian Inputs

    Publication Year: 1978, Page(s):1137 - 1147
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (771 KB)

    This paper is concerned with an exact analysis of DPCM (Differential Pulse Code Modulation) systems with stationary Gaussian inputs. We consider a class of digital communication systems in which DPCM is included as a member. An integral equation for the joint probability of the input and the state of the system is derived first. Solution of the equation is sought in the form of a power series in t... View full abstract»

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  • Fractional Speech Loss and Talker Activity Model for TASI and for Packet-Switched Speech

    Publication Year: 1978, Page(s):1253 - 1257
    Cited by:  Papers (90)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (475 KB)

    The cutout fraction in a TASI system is shown to bephi=frac{1}{np}sum_{k=c+1}^n (k-c) nchoose k p^{k}(1-p)^{n-k}wherenis the number of sources,cis the number of channels, andpis the probability that a source is issuing a talkspurt at a random time. This result is shown to hold independently of the probability density function of talkspurt duration. The s... View full abstract»

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  • Phaselock Loop Cycle Slipping Caused by Excessive Angle Modulation

    Publication Year: 1978, Page(s):1307 - 1309
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (303 KB)

    The occurrence of cycle slipping in a Phaselock Loop (PLL) FM Demodulator is discussed. Single spikes occur in a first order loop as the modulation limit is exceeded with sinusoidal modulation. A second order loop, however, experiences complete break-up, commonly referred to as bursting, of the demodulated output when the modulation limit is exceeded. An explanation is provided for the phenomenon ... View full abstract»

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  • Bounds on the Number of Possible Distinct Networks

    Publication Year: 1978, Page(s):1315 - 1316
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (217 KB)

    This note is concerned with the number of all distinct networks, also called connected graphs, or Cayley, or linear graphs that are possible forngiven nodes. Since for any practical number of nodes an explicit enumeration appears difficult, if not impossible, we offer an improved lower bound that enables tight approximation fornreasonably large. View full abstract»

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  • A First-Order Markov Model for Understanding Delta Modulation Noise Spectra

    Publication Year: 1978, Page(s):1316 - 1318
    Cited by:  Papers (7)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (292 KB)

    A first-order Markov process is used to model the sequence of quantization noise samples in delta modulation. An autocorrelation parameterCin the Markov model controls the shape of the noise spectrum, and asCdecreases from 1 to 0 and then to -1, the spectrum changes from a low-pass to a flat, and then to a high-pass characteristic. One can also use the Markov model to predict... View full abstract»

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  • [Back cover]

    Publication Year: 1978, Page(s): 0
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    Freely Available from IEEE
  • Energy Packing Efficiency for the Generalized Discrete Transforms

    Publication Year: 1978, Page(s):1257 - 1262
    Cited by:  Papers (18)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (472 KB)

    The concept of energy packing efficiency (EPE) of the Walsh-Hadamard transform (WHT) first proposed by Kitajima [1], is extended to other discrete orthogonal transforms. The concept as a criterion for evaluating the transforms is discussed. It is shown that the EPE is invariant for the generalized transforms as long as the ordering is the same. View full abstract»

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  • Angle Modulation Limits of a Noise-Free Phase Lock Loop

    Publication Year: 1978, Page(s):1129 - 1136
    Cited by:  Papers (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (680 KB)

    Methods are presented for determining the modulation limits of phase lock loop (PLL) FM demodulators. These limits establish the maximum deviation that the PLL can support (i.e., remain "inlock") based on the loop design parameters. The modulation limits are derived from experimental data on first and second order loops using sinusoidal and Gaussian noise modulation. The analysis of each PLL is br... View full abstract»

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  • Quantizing Characteristics for Signals Having Laplacian Amplitude Probability Density Function

    Publication Year: 1978, Page(s):1295 - 1297
    Cited by:  Papers (43)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (256 KB)

    The optimum (minimum mean-squared-error criterion) and optimum uniform quantizer characteristics for signals characterized by the Laplacian amplitude probability density function are given in tabular form. These results correct and extend previously published results. View full abstract»

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  • A Recursive Method Based on Case Analysis for Computing Network Terminal Reliability

    Publication Year: 1978, Page(s):1166 - 1177
    Cited by:  Papers (42)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (968 KB)

    In this paper a unified treatment is provided of the methods for computing terminal reliability based on recursive case analysis. The possible choices in case enumeration are discussed, and a rationale is given to support a particular policy. Simplification and decomposition techniques are also examined, and some experimental results are described, obtained with a computer program, which is a good... View full abstract»

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  • A Polarization Control System for Satellite Communications with Multiple Uplinks

    Publication Year: 1978, Page(s):1201 - 1211
    Cited by:  Papers (3)  |  Patents (15)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (832 KB)

    Several groups have designed polarization control systems to solve the rain-crosspolarization problem in satellite communications. However, the multiple-uplink problem still exists, i.e., one system cannot receive signals from different uplink stations with different rain conditions simultaneously. In order to solve this problem, a new scheme is developed in this paper based on the assumption that... View full abstract»

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  • On-Line Pseudo-Error Monitors for Digital Transmission Systems

    Publication Year: 1978, Page(s):1275 - 1282
    Cited by:  Papers (8)  |  Patents (5)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (632 KB)

    Pseudo-error detectors are devices which show great potential for the measurement of the bit error rate of an on-line digital communications link. They are implemented in the form of a second detector (in addition and in parallel to the traffic data bit detector) which is very perturbation-sensitive. They do not compromise the traffic handling capacity of the system. Four methods of generating the... View full abstract»

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  • Non-Coherent Pulse Detection with a Large Predetection Bandwidth

    Publication Year: 1978, Page(s):1297 - 1301
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (456 KB)

    For a non-coherent detection circuit with a broad-band pre-detection filter and narrow-band post-detection-filter, equations are obtained for the probability of detection of a pulsed sinusoidal signal embedded in white noise. The equations can be used to calculate the detection probability directly from envelope form, noise power at the input of the circuit and the impulse response of the postdete... View full abstract»

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  • Tracking Performance of Unbalanced QPSK Demodulators: Part I-Biphase Costas Loop with Passive Arm Filters

    Publication Year: 1978, Page(s):1147 - 1156
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (648 KB)

    Unbalanced quadriphase-shift-keying (QPSK) is an attractive means for transmitting two digital data streams which in general have different average powers, data rates, and data formats. Previous analyses of the tracking performance of Costas loop demodulators of unbalanced QPSK have accounted only for the filtering effect produced by the loop's two arm filters on the equivalent additive noise pert... View full abstract»

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  • Extension of an Adaptive Distributed Routing Algorithm to Mixed Media Networks

    Publication Year: 1978, Page(s):1262 - 1266
    Cited by:  Papers (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (472 KB)

    By modeling the broadcast portion of a mixed media network as a fully connected point-to-point network with link capacities varying as functions of the traffic rate it is possible to extend an adaptive distributed routing algorithm that was originally developed for point-to-point ground networks. Additional modifications for improved dynamic performance at the satellite interface message processor... View full abstract»

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  • Noise Removal from Chrominance Components of a Color Television Signal

    Publication Year: 1978, Page(s):1318 - 1321
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (464 KB)

    A solution to the problem of removing noise from the chrominance components of a color television signal is described. The inherent trade-off between noise removal and signal blurring is balanced adaptively using the luminance signal as a control for changing the characteristics of the chrominance filters. This adaptation is effective because: (1) in real pictures, most sharp changes of color are ... View full abstract»

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  • Experimental Performance of Point Process Estimators of Optical Pulse Delay

    Publication Year: 1978, Page(s):1239 - 1247
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (808 KB)

    Experimental results of estimating the delay of optical pulses in the presence of background noise based on the occurrence times of photoelectrons emitted by a direct detection photoelectric effect receiver are presented. Both minimum mean square error (MMSE) and maximum likelihood estimation techniques were used. The MMSE estimates of the delay of both Gaussian and rectangular optical pulses were... View full abstract»

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  • A Phase Adaptive Structure for Echo Cancellation

    Publication Year: 1978, Page(s):1211 - 1220
    Cited by:  Papers (15)  |  Patents (4)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (952 KB)

    Echo cancellation as an effective technique for echo control on telephone circuits is burdened by the appearance of carrier frequency offsets and phase jitter in some echo paths. In this paper we present a digital phase-adaptive structure for cancellation which will automatically compensate for echo path frequency offsets as large as 0.001 of the sampling rate without any reduction in return/loss ... View full abstract»

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  • Optimal Multistage Switching Networks

    Publication Year: 1978, Page(s):1282 - 1287
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (576 KB)

    We consider the problem of determining the multistage network with the fewest crosspoints for given sizes of input and output terminal sets, traffic load, number of stages and blocking probability. In this paper, we present a solution for this problem when the sizes of the input and output terminal sets are greater than a certain value. View full abstract»

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  • An Adaptive Technique for Local Distribution

    Publication Year: 1978, Page(s):1178 - 1186
    Cited by:  Papers (100)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (864 KB)

    A critical component of computer communications networks is local distribution, i.e., techniques for connecting geographically dispersed users to a central facility. A drawback to conventional polling techniques for local distribution is excessive overhead. Thus, in systems with many lightly loaded terminals, message delay is more a function of the time required to poll all terminals than of traff... View full abstract»

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  • The Choice of the Desired Impulse Response in Combined Linear-Viterbi Algorithm Equalizers

    Publication Year: 1978, Page(s):1301 - 1307
    Cited by:  Papers (50)  |  Patents (16)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (560 KB)

    Equalizer structures using the Viterbi Algorithm achieve at least order of magnitude performance improvement over linear equalizers on some intersymbol interference channels. Using a linear equalizer to shape the original channel impulse response to some shorter desired impulse response (DIR) is a technique which reduces the complexity of the Viterbi Algorithm equalizer. This paper looks at three ... View full abstract»

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  • Tracking Performance of Unbalanced QPSK Demodulators: Part II-Biphase Costas Loop with Active Arm Filters

    Publication Year: 1978, Page(s):1157 - 1166
    Cited by:  Papers (8)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (640 KB)

    A previous Costas loop study by the author demonstrated that for biphase modulation considerable improvement in tracking performance could be obtained by employing active arm filters of the integrate-and-dump type as opposed to passive arm filters. The purpose of this part, then, is to demonstrate that a similar performance improvement can be obtained for an unbalanced QPSK modulation. View full abstract»

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  • An Automated Technique of Communications Protocol Validation

    Publication Year: 1978, Page(s):1271 - 1275
    Cited by:  Papers (32)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (560 KB)

    An interaction between two communicating processes can be defined in terms of a protocol or set of rules governing the exchange of messages between them. For any given protocol, it is a significant problem to determine whether or not errors can occur when the processes interact. In this paper, we describe an implementation of a recent theory of Zafiropulo, which defines protocols in terms of the i... View full abstract»

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  • A Comparison of Information Policies for Minimum Delay Routing Algorithms

    Publication Year: 1978, Page(s):1266 - 1271
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract |PDF file iconPDF (632 KB)

    The problem of routing in a computer networks is dealt with by separating the information problem and the control problem. Several classes of information policies are examined, and numerical comparisons are made of their performance, using representative values of network parameters. Routing based on the expected values of delay, rather than actual values of delay, is shown to be superior to the o... View full abstract»

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Aims & Scope

IEEE Transactions on Communications focuses on all telecommunications including telephone, telegraphy, facsimile, and point-to-point television by electromagnetic propagation.

 

 

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Naofal Al-Dhahir
University of Texas at Dallas