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Communications, IEEE Transactions on

Issue 2  Part 1 • Date February 1979

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  • [Front cover and table of contents]

    Publication Year: 1979 , Page(s): 0
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    Freely Available from IEEE
  • Introduction

    Publication Year: 1979 , Page(s): 261 - 264
    Cited by:  Papers (1)
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    Freely Available from IEEE
  • [Back cover]

    Publication Year: 1979 , Page(s): 0
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    Freely Available from IEEE
  • An Integrated Per-Channel PCM Encoder Based on Interpolation

    Publication Year: 1979 , Page(s): 272 - 278
    Cited by:  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (864 KB)  

    A novel technique called interpolation has been used to integrate a per-channel PCM encoder in a standard digital circuit technology. This encoder converts voiceband analog signals to both an oversampled 1-bit code and uniform PCM with μ-law companding noise. The circuit comprises approximately 550 integrated injection logic gates together with a resistive digital-to-analog converter, a voltage reference, and a simple differential amplifier. The encoder is part of a full PCM codec chip set suitable for a broad range of voiceband telecommunication applications. View full abstract»

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  • Capacity Limits for Binary Codes in the Presence of Interference

    Publication Year: 1979 , Page(s): 441 - 448
    Cited by:  Papers (5)
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    Capacity limits are obtained when binary codes are used for communications over channels in the presence of high levels of interference. The ideal additive Gaussian noise channel and the Rayleigh fading channel are considered. For each channel, the performance of four types of decoders are considered. Both binary and channel measurement (soft decision) decoding are considered; for each of these cases, performance results are obtained when interference can and cannot be detected before decoding. Thus, capacity limits for the minimum achievable E_{b}/N_{o} as a function of the code rate R are obtained for eight different channel models of interest. View full abstract»

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  • Simulation and Analysis of the Weighted Erasure Decoding

    Publication Year: 1979 , Page(s): 483 - 488
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    A decoding scheme called w -distance decoding (or weighted erasure decoding) has been studied for decoding binary block codes on Q -ary output channels by computer simulation and analytic derivation of the probabiliiy of error bound. Optimum distribution of w -weights and the optimum threshold level of quantization are obtained by both simulation and minimization of the probability of error bound. The asymptotic behavior (signal-to-noise ratio \rightarrow \infty ) of the error bound is determined by numerical methods with the help of a digital computer. View full abstract»

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  • A Single-Chip I2L PCM Codec

    Publication Year: 1979 , Page(s): 317 - 322
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    A single-chip CPCM codec is described. This chip, which is fabricated in bipolar technology, meets all the D3 specifications. The circuit is capable of operating in a fully asynchronous transmit and receive mode, and provisions are made, for zero-code suppression and A/B signaling. Even with this signaling, the codec achieves a worst case idle-channel noise of 13 dBrn C 0. View full abstract»

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  • Improvements in Block-Retransmission Schemes

    Publication Year: 1979 , Page(s): 524 - 532
    Cited by:  Papers (34)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (848 KB)  

    Consider the case where an n -digit block encoded word cannot be decoded reliably and a second block of n redundant digits is sent to allow the receiver to make a new try based on the combined information received. Two classes of schemes are proposed and analyzed which give significantly better performance than is obtained by sending a repeat of the first block, yet do not require excessive decoding complexity. One approach is to consider small sub-blocks of the original n -digit code as the data digits of a short rate one-half code. The other approach is to treat the first sending as the data digits of a systematic convolutional code of short constraint length. Comparisons are made for the white Gaussian noise channel and the erasure channel. The comparisons are limited to an assessment of the improvement gained after two sendings. Procedures using length 4 sub-blocks and using convolutional codes with constraint lengths as short as 2 or 3 digits yield considerable improvement over block retransmission. For the case of the erasure channel, a very simple decoding rule is devised for the convolutional code case. View full abstract»

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  • A Single-Chip CMOS PCM Codec

    Publication Year: 1979 , Page(s): 312 - 317
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    A single-chip full duplex per channel PCM codec implemented in a metal gate CMOS process is presented. An 8-bit companding DAC, a novel autozeroed analog subsystem, and a 3.5-MHz frame interface control logic comprise the 175 × 195-mil integrated circuit. The DAC is implemented with matched n -channel devices and utilizes redundancy and feedback to achieve the required accuracy. The analog subsystem contains two sample and hold circuits, autozeroing circuitry, CMOS amplifiers, and a fast CMOS compatator. The circuit operates from a single supply, consumes 90 mW (typ) and features a powerdown capability to less than 1 mW (max). Individual component performance and the resulting system performance are quantified within the text. View full abstract»

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  • Multiple-Tone Detector with CCD Filters

    Publication Year: 1979 , Page(s): 349 - 354
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    An integrated-circuit multiple-tone detector is demonstrated. It is made of three transversal CCD filters with nonoverlaping bandpass characteristics for tone (i.e., sine wave signal) separation and each filter has an internally matched threshold level for reproducible tone detection. When an in-band tone exceeds the threshold level, the output for that particular filter is a square wave with the same period as the tone period. The chip was fabricated in the NMOS double layer polysilicon technology, operates on three power supplies and a master clock, measures 85 × 283 mils and dissipates only 100 mW of power. Voltage tracking, offset canceling, and area matching techniques are used in order to reduce the dependence on process or voltage supply variations. View full abstract»

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  • A PCM Voice Codec with On-Chip Filters

    Publication Year: 1979 , Page(s): 323 - 331
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1192 KB)  

    A monolithic NMOS coder/decoder (codec) with associated CCD transversal minimum-phase filters has been successfully implemented. The codec operates by charge redistribution in a binaryweighted capacitor array, with a resistor chain to define individual steps. The experimental performance compares well with PCM codecs implemented with discrete components. View full abstract»

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  • Design of an Integrated Circuit for the T1C Low-Power Line Repeater

    Publication Year: 1979 , Page(s): 367 - 378
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    A low-power T1C (3.152-Mbits/s) digital repeater has been designed which reduces the power requirements by a factor of approximately four compared to the previous version. The new design operates at 60 mA and 6.2 V, or 372 mW, a power level essentially identical to new T1 repeater designs which run at one-half the T1C rate. As a result, the maximum distance between powering stations has been increased from approximately 22 to 44 mi. The silicon integratedcircuit chip contains all the active circuitry necessary for one-way regeneration. The circuitry used for equalization, clock extraction, and regeneration are described in detail. Complementary bipolar (CBIC) technology, which made possible the power reduction and improved performance, is described in general terms. View full abstract»

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  • Optimal Blocklengths for ARQ Error Control Schemes

    Publication Year: 1979 , Page(s): 488 - 493
    Cited by:  Papers (32)  |  Patents (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (592 KB)  

    Optimal blocklengths are investigated for various ARQ schemes used for error control in data transmission systems in independent-bit-error and Poisson-distributed block-error channels. A number of results relating to optimum block length for various ARQ schemes are collected for easy reference. New results are obtained for some of these schemes. The product of this investigation is suggested procedures for computing optimal blocklengths. Examples are given. View full abstract»

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  • A Single-Channel PCM Codec

    Publication Year: 1979 , Page(s): 283 - 295
    Cited by:  Papers (5)  |  Patents (3)
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    A single-channel PCM codec is described which is being manufactured for use in the new British Post Office (BPO) range of digital PABX's. The codec works on the principle of converting to and from PCM using an intermediate delta-sigma modulation code format. This technique allows relatively simple analog circuitry to be used in conjunction with a digital LSI chip to perform the conversion between the intermediate code and PCM. The codec meets all the relevant CCITT Recommendations with significant operating margins. View full abstract»

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  • Optimal Structures of Benes' Switching Networks

    Publication Year: 1979 , Page(s): 433 - 437
    Cited by:  Papers (5)
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    The class of switching networks, composed of stages of identical square switches arranged symmetrically around a center stage (Benes' networks), is considered. The synthesis problem of selecting from this class a rearrangeable network with the minimum number of crosspoints is solved. Benes' approach, (using relation of covering), is taken into consideration. The new structures of the networks are in some cases different than those already known. Modifications of Benes' theorems result in lowering the number of stages of a switching network with the minimum number of crosspoints. This lowering can bear some practical significance, which could simplify the control devices. A model comparison is given of the known and new results. View full abstract»

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  • Measured Performance of a Laser Intensity Subcarrier Phase Shift Keyed Direct Detection Optical Communication System

    Publication Year: 1979 , Page(s): 522 - 524
    Cited by:  Papers (1)
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    The performance of both optimal and much simpler suboptimal direct detection optical communication receiver structures was directly measured and found to be nearly identical for laser intensity subcarrier PSK communication through both free space and atmospheric (log-normal fading) channels. View full abstract»

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  • Monitoring Mobile Packet Radio Devices

    Publication Year: 1979 , Page(s): 509 - 517
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    A store-and-forward broadcast radio network with mobile switching nodes is considered. The problems of monitoring connectivity changes in the network and updating information in switching nodes to enable routing of messages are addressed. Analytical models are developed for determining the fraction of time that switching nodes have correct information as a function of trajectory and speed for mobility, monitoring rate, traffic load, and network topology. The problems are parametrically investigated and results of monitoring rate to obtain performance requirements are obtained. These studies show that the monitoring rate is very sensitive to velocity; specifically, as the velocity doubles, so does the monitoring rate. These results are a first step in obtaining meaningful operating parameters to be used in experimental networks. View full abstract»

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  • The LT-1 Connector--A Conventional Transmultiplexer

    Publication Year: 1979 , Page(s): 355 - 360
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1184 KB)  

    The LT-1 connector has been designed to provide an economical means of terminating analog transmission facilities on the No. 4ESS, a digital toll switching machine. It performs a bilateral conversion between two 12-channel analog group signals in the 60-108-kHz band and a 24-channel digital digroup at 1.544 Mbits/s. In addition, signaling information in the form of a 2600-Hz tone must be converted to the digital format. The connector has been implemented with conventional per-circuit technology but achieves significant savings compared to back-to-back channel banks. This is accomplished by eliminating redundant circuitry and using a number of custom designed silicon integrated circuits. This paper gives a description of the design and some typical performance data. View full abstract»

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  • A Monolithic Phase-Locked Loop with Post Detection Processor

    Publication Year: 1979 , Page(s): 413 - 419
    Cited by:  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (768 KB)  

    This paper details the design and fabrication of a highfrequency (50-MHz) phase-locked loop with a post detection processor which allows the detection of FSK signals with few external components. The circuit operates with a single 5-V supply and has TTL compatible inputs and outputs. View full abstract»

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  • An NMOS Telephone Codec for Transmission and Switching Applications

    Publication Year: 1979 , Page(s): 305 - 311
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    This paper describes a monolithic high-feature per-channel companded PCM coder/decoder (codec) and implications of the advanced architecture for fixed and variable time-slot applications. Technology tradeoffs are identified, and implementation of the critical analog circuit functions in n -channel MOS technology is discussed. These circuits include the first commercial embodiment of a novel buried-ion voltage reference. View full abstract»

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  • Orthogonal and Quasi-Orthogonal Tree Codes with Applications to Multiple Access

    Publication Year: 1979 , Page(s): 449 - 460
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (928 KB)  

    The performance of orthogonal and quasi-orthogonal tree codes is considered for incoherent and coherent systems. In addition, several alternative receiver structures using hard quantizing and "greatest-of" detection are treated. Upper bounds on error probability are derived and are used as a basis for system comparison. An application of quasi-orthogonal tree codes to a multiple access environment is presented as an example and discussed. View full abstract»

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  • Key Aspects in the Development of a 48-Channel Duobinary PCM Repeater

    Publication Year: 1979 , Page(s): 379 - 389
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1368 KB)  

    This paper describes the background and the actual circuit designs in the development of the 48-channel modified duobinary PCM line repeater. The reasons for the choice of the modified duobinary coding technique are explained. The equalization requirement of the signal in terms of the channel roll-off factor is obtained by considering the crosstalk penalty, intersymbol interference, and ease of hardware implementation. The hardware implementations of the various repeater sections-equalization, clock recovery, and data regeneration-are outlined. The main considerations in circuit design are circuit size, power consumption, and tolerance to parameter variations. These considerations are of prime importance for the modified duobinary system to retrofit the existing T1 system. Such requirements resulted in the extensive use of integrated circuits and thick-film hybrids and also in the development of a new clock recovery method for a correlative pulse sequence called the "slicer method." View full abstract»

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  • A Partial Response Binary Communication System with Erasure

    Publication Year: 1979 , Page(s): 493 - 498
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Formulas for probability of error (Pe) and probability of erasure (Po) for a binary communication system with partial response signals (duobinary, dicode, modified duobinary) and either decision feedback or precoding are presented.The input data are binary,but the output data are ternary where the third symbol represents erasure.The system with decision feedback is not improved(penotreduced) by the introduction of erasure,while a significant improvement occurs in the system with precoding. View full abstract»

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  • Antialiasing Filter with an Improved S/N Ratio

    Publication Year: 1979 , Page(s): 430 - 431
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    If a CCD low-pass filter is used for antialiasing, a higher data rate is necessary at the input compared to the output. This difference in the data rate is used to increase the signal-to-noise ratio. By adding a given number of consecutive charge packets at the output stage, the output data rate can be reduced until the Nyquist theorem for the output signal is violated. By summing up those charge packets, the signal is added arithmetically whereas the noise, not being correlated, is added geometrically. This results in an improvement of the S/N ratio equal to the number of charge packets added. View full abstract»

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  • A Per-Channel LSI Codec for PCM Communications

    Publication Year: 1979 , Page(s): 265 - 271
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    An LSI codec for voiceband signals is presented. A modified counting-type encoding technique is employed to realize the codec, which uses coarse and fine reference current to discharge the integrating capacitor. The technique makes possible the realization of a high-speed counting-type codec for voice signals without imposing severe requirements on device parameters. This codec is composed of two LSI chips, i.e., a bipolar chip and an NMOS chip. An estimation sample of the LSI codec is fabricated and evaluated. Measured data of the codec performance are very close to the theoretically expected value. The performance assures that the device can be applied to channel banks, local switches, toll switches, and EPBX's. 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.

 

 

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Meet Our Editors

Editor-in-Chief
Robert Schober
University of British Columbia