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Communications, IEEE Transactions on

Issue 9 • Date Sep 1990

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Displaying Results 1 - 25 of 45
  • On the statistical dependence of hits in frequency-hop multiple access

    Publication Year: 1990 , Page(s): 1483 - 1494
    Cited by:  Papers (26)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (800 KB)  

    The statistical dependence of hits due to multiple-access interference in an asynchronous slow-frequency-hop packet radio network in which the radios employ memoryless hopping patterns is described. Models in which hits are conditionally independent given the number of interfering packets are investigated. It is shown that if the conditional probability of a hit is chosen appropriately, the distri... View full abstract»

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  • A baud-rate full-duplex transmission unit for subscriber loops

    Publication Year: 1990 , Page(s): 1495 - 1503
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (832 KB)  

    A baud-rate full-duplex digital transmission unit for 144-kb/s basic access over an existing subscriber loop plant is described. The adaptive operations performed include echo cancellation, decision feedback equalization, reference control, and timing recovery. The unit operates at the baud rate, allows a fully digital implementation, and requires no special training sequences. Baud-rate timing re... View full abstract»

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  • Sequential CFAR detectors using a dead-zone limiter

    Publication Year: 1990 , Page(s): 1375 - 1383
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (728 KB)  

    The performances of some proposed sequential constant-false-alarm-rate (CFAR) detectors are evaluated. The observations are passed through a dead-zone limiter, the output of which is -1, 0, or +1, depending on whether the input is less than -c, between -c, and c, or greater than c , where c is a constant. The test statistic is the sum of the outputs. Th... View full abstract»

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  • Random-access systems with a time varying channel

    Publication Year: 1990 , Page(s): 1293 - 1297
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (384 KB)  

    A random multiple-access system which employs a collision resolution algorithm for accessing a common time-varying channel is considered. The channel is assumed to be in one of two states. In each state, the channel is characterized by a general discrete memoryless channel and the transitions between the two states are assumed to be Markovian. A set of sufficient conditions for the ergodicity (sta... View full abstract»

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  • A number theoretic approach to time division multiplexing

    Publication Year: 1990 , Page(s): 1504 - 1510
    Cited by:  Patents (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (656 KB)  

    A systematic approach to synchronous time division multiplexing (TDM) in embedded systems employing TDM as a switching fabric in the form of a bus is presented. The benefits of this approach are increased system capacity, individual and unrestricted circuit creation for all channels regardless of their bandwidth, latency ranging from a fraction of a bit to several bits, and independent tracking of... View full abstract»

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  • Application of scale space to image coding

    Publication Year: 1990 , Page(s): 1585 - 1591
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (628 KB)  

    The continuous formulation of scale space is briefly reviewed. It is shown that deriving a discrete formulation of scale space requires the solution to a more general problem; the optimum approximation of a signal by local patterns. The consequences of the theory for the Laplacian image pyramid are discussed. A pyramid coding scheme based on the discrete scale-space formulation is derived. Prelimi... View full abstract»

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  • A measurement study of diskless workstation traffic on an Ethernet

    Publication Year: 1990 , Page(s): 1557 - 1568
    Cited by:  Papers (67)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (1336 KB)  

    The traffic on a 10-Mb/s Ethernet local-area network that connects diskless workstations to file servers in a university environment is analyzed. The traffic is substantially heavier than has been recorded in previous studies; measured over 1-s intervals, it frequently exceeds 30% of the network bandwidth. The distribution of packet lengths and the patterns of packet interarrival times are interpr... View full abstract»

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  • An investigation of Gaussian tail and Rayleigh tail density functions for importance sampling digital communication system simulation

    Publication Year: 1990 , Page(s): 1288 - 1292
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (332 KB)  

    The gains achieved by the use of importance sampling in communication system simulation are strongly influenced by the choice of the biased input noise distribution. The Rayleigh tail and the Gaussian tail distributions are investigated for use as biased distributions in importance sampling. The robustness of these schemes with respect to the estimate of the unknown error probability is examined. ... View full abstract»

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  • Minimal transmitter complexity design of analytically described trellis codes

    Publication Year: 1990 , Page(s): 1352 - 1358
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (648 KB)  

    G. Ungerboeck's (1982) design rules for a class of bandlimited codes called trellis codes are reviewed. His design of the trellis is based on a set partitioning of the signal constellation, and he realized these trellis codes by a convolutional encoder followed by a mapping rule from the coder output to modulation symbols. R. Calderbank and J.E. Mazo (1984) showed how to realize trellis codes for ... View full abstract»

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  • An algorithm for the design of generalized quantizers for detection

    Publication Year: 1990 , Page(s): 1384 - 1390
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (616 KB)  

    A procedure based on the generalized Lloyd algorithm approach using a sequence of independent noise samples to design M-region generalized quantizers for signal detection is presented. Included in this case are the conventional M-interval quantizer detectors. The quantizer parameters for S.A. Kassam's (1985) four-region generalized quantizer detector are computed using various sa... View full abstract»

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  • Error control criteria in the message transfer part of CCITT Signaling System No.7

    Publication Year: 1990 , Page(s): 1630 - 1636
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (472 KB)  

    Three error correction methods are specified for CCITT Signaling System No.7: the preventive cyclic retransmission (PCR) method for relatively long signaling links, the basic method for relatively short links, and the basic method with repetition of signal units as an option. The qualitative characteristics of these methods are compared. This comparison shows that the PCR method is simpler to achi... View full abstract»

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  • Polar quantizing for coded PSK transmission

    Publication Year: 1990 , Page(s): 1511 - 1519
    Cited by:  Papers (12)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (560 KB)  

    The issue of demodulator quantization prior to decoding in error control systems employing M-ary phase-shift keying (PSK) as a modulation technique is considered. The use of angle-only, or polar, quantization with JM levels, which is an easily implemented alternative to rectangular quantization, is described. The R0 parameter is presented as an e... View full abstract»

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  • A multiservice high-performance packet switch for broad-band networks

    Publication Year: 1990 , Page(s): 1607 - 1615
    Cited by:  Papers (5)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (828 KB)  

    An input queued packet switch for broadband networks that supports data link connections and whose capacity is not constrained by the capacity of a single packet channel is described. The switch bandwidth is allocated at two different times. At connection setup time, an output data link (a channel group) is selected on which some bandwidth is reserved for the new call. At transmission time, specif... View full abstract»

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  • Vector quantization of pitch information in Mandarin speech

    Publication Year: 1990 , Page(s): 1317 - 1320
    Cited by:  Papers (31)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (296 KB)  

    A method of quantizing the shape of pitch contour segments of Mandarin speech by using orthogonal polynomial representation and vector quantization techniques is proposed. Only a very limited number of representative pitch contour patterns of words can be found in Mandarin conversation; therefore, pitch information can be represented by the shape and the length of the pitch contour segment word by... View full abstract»

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  • Compression of binary facsimile images by preprocessing and color shrinking

    Publication Year: 1990 , Page(s): 1592 - 1598
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (684 KB)  

    Algorithms for preprocessing, global modeling and segmentation, local modeling and representation, and binary encoding of facsimile images are proposed, and their performance is examined. Some binary morphological operations that can be used to improve the quality and increase the compressibility of binary images and the modeling of binary images are discussed. The techniques are incorporated into... View full abstract»

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  • A new method for Viterbi decoder simulation using importance sampling

    Publication Year: 1990 , Page(s): 1341 - 1351
    Cited by:  Papers (48)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (1116 KB)  

    Each simulation run simulates a single error event-that is, a subsequence of incorrect trellis branching decisions-and importance sampling is used to emphasize important nontrivial error events. The fundamental principles of the error event simulation method in conjunction with importance sampling are reviewed. The importance sampling background for coded communications systems is discussed in the... View full abstract»

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  • Spectral analysis of 49 years of rainfall rate and relation to fade dynamics

    Publication Year: 1990 , Page(s): 1359 - 1366
    Cited by:  Papers (17)  |  Patents (98)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (700 KB)  

    The nature of the rainfall rate R(t) as a transient random process is presented in the context of microwave attenuation and fade dynamics. Using 49 years of data recorded in Barcelona, the spectral densities of energy and power and the autocorrelation function are presented, together with their analytical model. Examples for specific rain events are also presented. Several regime... View full abstract»

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  • Overflow analysis for finite waiting room systems

    Publication Year: 1990 , Page(s): 1569 - 1577
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (948 KB)  

    A system of multiple primary queues with finite waiting rooms, where blocked jobs are allowed to overflow onto a common secondary queue, also with finite waiting room, is considered. Poisson arrivals and exponentially distributed service times, possibly different ones, are assumed at each primary service facility. Service facilities consist of a single server or multiple servers. Based on a simple... View full abstract»

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  • Symbol synchronization for digital signals with multisegment trajectory: digital data transition tracking loop

    Publication Year: 1990 , Page(s): 1637 - 1644
    Cited by:  Papers (2)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (616 KB)  

    The symbol synchronizer presented is an all-digital data transition tracking loop which permits simple implementation and voltage control of the loop bandwidth. The equivalent loop integration constant is changed by changing the threshold level of a comparator at the output of the loop phase error detector. Phase error probability distribution function, its variance, and the average probability of... View full abstract»

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  • Coding of optical on-off keying signals impaired by phase noise

    Publication Year: 1990 , Page(s): 1301 - 1307
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (376 KB)  

    The benefits of coding for an optical communication system that employs binary on-off keying and heterodyne detection are quantified. The system is impaired by laser phase noise as well as by additive white Gaussian noise (AWGN). A receiver structure especially designed to mitigate the effects of phase noise in the presence of AWGN is assumed. This special receiver structure requires a wider-band ... View full abstract»

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  • On the error probability of coded frequency-hopped spread-spectrum multiple-access systems with more than one code symbol per dwell interval

    Publication Year: 1990 , Page(s): 1321 - 1324
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (280 KB)  

    The multiple-access capability of an asynchronous, frequency-hopped spread-spectrum (FH-SS) communication system employing error correcting codes is reviewed. Many current FH-SS systems employ error correcting codes with more than one code symbol per dwell interval. A method of computing the codeword error probability induced in such spread-spectrum systems is presented. The codeword error probabi... View full abstract»

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  • The convexity of loss rate in an Erland loss system and sojourn in an Erlang delay system with respect to arrival and service rates

    Publication Year: 1990 , Page(s): 1314 - 1316
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (192 KB)  

    The Erlang loss system is a system in which customers arriving in a Poisson stream of arrival rate λ are served by a group of n servers, with a mean service time of 1/μ. Arrivals that find all servers busy are blocked and cleared from the system. The Erlang delay system is a system in which customers who find all servers busy wait in a queue until served by the first available ... View full abstract»

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  • Performance analysis of CSMA/CD networks with a buffered gateway

    Publication Year: 1990 , Page(s): 1404 - 1418
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (876 KB)  

    A single CSMA/CD (carrier sense multiple access with collision detection) local area network which is connected to other networks by a gateway with finite buffer capacity is described. Its performance is analyzed by using an embedded Markov chain. For the service discipline of packets queuing at the gateway, three cases are considered: G-limited service discipline, E-limited service discipline, an... View full abstract»

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  • A single-server queue with vacations and gated time-limited service

    Publication Year: 1990 , Page(s): 1454 - 1462
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (808 KB)  

    An M/G/1 queue with server vacations and gated time-limited service is analyzed. At each visit, the server serves the queue up to a fixed amount of time. When the time expires or after all candidate customers have been served, whichever occurs first, the server takes a vacation. The service policy is gated, since only those customers present at the beginning of a server visit (poling instant) are ... View full abstract»

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  • Near optimum timing recovery for digitally implemented data receivers

    Publication Year: 1990 , Page(s): 1333 - 1336
    Cited by:  Papers (2)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandAbstract | PDF file iconPDF (356 KB)  

    A timing recovery scheme based on the maximization of the spectrum of the sampled received signal at the frequency of f-=1/2T is proposed. The quadrature amplitude modulated data signals are considered. Algorithms for both initial adjustment of the timing phase and its tracking during transmission of actual data bits are developed. The algorithms are tested by computer simulatio... 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
Robert Schober
University of British Columbia