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Communications, IEEE Transactions on

Issue 3 • Date March 1976

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Displaying Results 1 - 18 of 18
  • [Front cover and table of contents]

    Page(s): 0
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    Freely Available from IEEE
  • Guest Editorial: Telecommunications in Latin America

    Page(s): 289 - 290
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    Freely Available from IEEE
  • [Back cover]

    Page(s): 0
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    Freely Available from IEEE
  • Pulse and Spectrum Manipulation in the Minimum (Frequency) Shift Keying (MSK) Format

    Page(s): 381 - 384
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    The minimum (frequency) shift keying (MSK) format is generalized to enable further improvements in the spectrum while retaining the well-known constant envelope property and the excellent communications efficiency of MSK. A specific alternative to MSK is presented, and the spectrum is compared with that of MSK. The theoretical limitations on possible further spectrum improvements are discussed. View full abstract»

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  • On the Transmitted Power in Generalized Partial Response

    Page(s): 348 - 352
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    The advantages with regard to noise enhancement of certain suboptimum nonlinear techniques for "equalization" of linear distortion on channels used for digital data transmission have recently received considerable attention. These nonlinear schemes fall into two classes: decision feedback and nonlinear precoding. Yet each of these methods has an associated peculiarity which has impeded attempts to give firm bounds on performance. Thus, for decision feedback error propagation has caused the analytical pains, while for nonlinear precoding of anL-level alphabet the unknown increase in transmitter power has been culpable. The former problem has recently received successful attention by one of the present authors and some colleagues. Here we address the concomitant problem for nonlinear precoding and its extension to quadrature amplitude modulation (QAM) and show that the transmitted normalized powerPsatisfies(L^{2} - 1)/3 leq P leq (L^{2} - 1)/3 + 1. View full abstract»

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  • Multipoint Private Line (MPL) Access Delay Under Several Interstation Disciplines

    Page(s): 339 - 348
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    A multipoint private line (MPL) network is designed to operate within specified system-performance objectives. Performance objectives for some types of computer-communications networks are stated in terms of access-delay statistics which measure the grade of service experienced by the stations bidding for access to the private line. Access delay is defined to be the time from when a message reaches the head of its queue at the station-and no message from its queue is being processed-until transmission of the message begins. Using simulation and some analysis, we examine and compare the access delay statistics for an MPL circuit under each of four possible service disciplines for the stations on the circuit. The results in this paper have proven useful in designing certain types of MPL networks for a variety of system parameters. View full abstract»

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  • Discrete Estimation of Continuous Angle-Modulated Signals Over Multipath Channels for Aeronautical Communication

    Page(s): 365 - 374
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    The multipath channel for communication between an aerospace vehicle and a ground terminal is modeled by a multiplicative first-order Markov process. The multiplicative process is treated as a component of the message model and the discrete-time demodulation algorithms using the extended Kalman nonlinear estimation technique are developed for continuous-time angle-modulated signals. The equivalent baseband form of the demodulator structure is derived. Two examples of the message process are discussed for an FM system. The simulation results are presented for various values of the bandwidth expansion ratio and the additive SNR. The performance of the baseband algorithms is discussed. View full abstract»

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  • Kalman Filter Equalization for QPSK Communications

    Page(s): 361 - 364
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    The discrete complex Kalman filter is considered as an equalizer for quadrature phase-shift keyed (QPSK) systems in the presence of additive noise and intersymbol interference (ISI). When the channel is unknown, an adaptive Kalman equalizer is used in which the channel complex tap gains are estimated by decision feedback. View full abstract»

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  • Telecommunication Training in Latin America: A Viewpoint from Venezuela

    Page(s): 329 - 331
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    The main differences between the problems of telecommunications training in Latin America and those in well industrialized countries are stated, the solution through national training centers is briefly described, and the need and possibility of regional training centers serving several countries is discussed and illustrated with relevant information about Venezuela's Telecommunication Studies Center. View full abstract»

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  • An Overview of Latin American Telecommunications, Past, Present, and Future

    Page(s): 290 - 305
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    A historical perspective on the development of telecommunications in Latin America in the last decade is evolved in this introductory paper. The current national telecommunication situation is then considered with reference to three countries-Honduras, Colombia, and Brazil-with emphasis on planning and future programs. Because of the accelerating impact that satellite communication has had on Latin American telecommunications development, international, intercontinental, domestic, and regional satellite communication operation and plans are treated. Finally, some broad-gauge objectives for development and integration of Latin American telecommunications to provide economic growth and social and cultural benefits are presented. View full abstract»

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  • Differential Phase-Shift Keying Performance on L-Band Aeronautical Satellite Channels: Test Results and a Coding Evaluation

    Page(s): 374 - 380
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    The problem of communicating binary information from ground to aircraft viaL-band aeronautical satellite channels is addressed, with particular attention given to the effect of and means of combating diffuse-scattered multipath interference. Differential phase-shift keying (DPSK) is considered throughout. Test results of a recent flight-test program are summarized and compared to theory for uncoded DPSK. We then discuss and evaluate the use of diffuse convolutional codes in conjunction with threshold decoding to improve error probability on the fading channel. Simulation has shown that a power saving of 8 dB may be gained at 10-5error rate for typical channel conditions with very little complexity. View full abstract»

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  • Telecommunications and Industrial Development

    Page(s): 305 - 311
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    Given a demonstrable correlation between telecommunications and industrial development, an interesting underlying question is: How can a telecommunication system be planned to achieve overall industrial development goals? A response could focus on the technical capabilities of a network, on the telecommunication equipment supply arrangements, and on the tariff structure. High telephone density is a technical attribute of primary importance because telecommunications' value for industrial development is that it provides an infrastructure. This value is not realized until a "critical mass" of telephone density is achieved. Where demand for telecommunication service substantially exceeds supply, screening criteria can be used to give certain classes of users higher priority in concert with industrial development goals. A second area of importance is the selection of plant technology which involves decisions that will affect technical capabilities of the network for 15-20 years or more; for example, crossbar, and electronic switching systems each possess certain advantages which should be considered in the light of local conditions. A local telecommunication equipment manufacturer is a participant in national industrial development. Efficient production of equipment might be supported by continuous and substantial demand from trading partners within a block such as the Andean Common Market. To reduce a telecommunication company's equipment costs, competitive procurement and negotiated allocation of supply contracts are two methods that are feasible particularly with transmission equipment such as microwave radios and cable. Alternatively, where a favored supplier relationship exists, the telecommunication company could benefit from the support of a research, development and engineering group in assessing its product choices. Tariff structure is a major allocator of telecommunication resources that is controllable by telecommunication planners. Price rationing is a conservative response to unsatisfied demand but does not respond fully to the needs of industrial development. Seeking to achieve a "critical mass" of telephone density through subsidized rates would be more responsive. Other tariff structure issues include use of measured versus flat rate - local services, selection of criteria for drawing of local calling area boundaries and utilizing local calling area size as a basis for discrimination in rates. In response to inflation, continual modification of tariff structure is more sensitive to the needs of industrial development than the indexing of the rates, although the latter option requires fewer analytical resources. View full abstract»

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  • Rural Telecommunications in Latin America

    Page(s): 325 - 329
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    Over the last decade, Latin American telecommunications authorities have shown a growing concern for rural services reflecting their governments' increasing interest in this subject in the context of social and economic development. This paper presents a broad review of the existing situation of rural telecommunications in Latin America; details, though interesting in some cases, are not included except when necessary for the interpretation of the general problem. Rural communications, as reported here, refers only to telephony and telegraphy; other services, especially radio and television broadcasting, are not considered although they can be related to rural programs. View full abstract»

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  • A Simulation Model of the TIDAS Computer Network

    Page(s): 352 - 358
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    To study the performance of a full-duplex messageswitched computer network, called TIDAS-T, during various conditions a simulation model has been built in order to simulate the procedure. The model describes the communication and the line procedure in the TIDAS network very closely. The only simplification made is that the processing time in the node computers is disregarded as being insignificant in comparison with the transmission and queueing times. The model, programmed in SIMSCRIPT 1.5, is very flexible because all important parameters are given by input data. The outputs from a simulation differ from run to run due to the object defined by input data parameters. The statistical results are mostly presented as complete statistical distributions. It has turned out that the model has been a splendid tool in order to study and view the consequences of different design approaches. Some of the problems in building such a complex model axe elucidated and some simulation runs are given as illustrations. As the model is very flexible it may be used to study computer networks other than TIDAS. View full abstract»

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  • Linking Electricity with the Telephone Demand Forecast: A Technical Note

    Page(s): 322 - 325
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    The electricity demand forecast can be used profitably, either as a short-cut or as a long-term effort, in telephone demand forecasting. Preliminary application of such effort to two Latin American countries offers fruitful insight and results. Further research in this area may pave the way to useful collaboration between planners in energy and telecommunications development projects. View full abstract»

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  • Delay-Lock Tracking of Stochastic Signals

    Page(s): 331 - 339
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    The measurement and tracking of the delay between two versions of a stochastic signal by cross-correlation techniques is considered. Such techniques have broad applications, e.g., interferometry, noncontact speed and distance measurement, etc. The paper begins by discussing the functional diagram of the tracking system. From this diagram a mathematically equivalent model of the system is derived and its similarities to the well known baseband model of the phase-locked loop are discussed. Using Fokker-Planck (F-P) techniques the performance of the system, as a function of fundamental system parameters, is computed and graphically illustrated. These results are then compared with experimental results obtained by computer simulation. View full abstract»

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  • Costa Rica: A Case Study of the Telephone Cost Structure on a Service-Related Basis

    Page(s): 311 - 321
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    This paper is based on a study made by the author in 1972-1973. The cost information corresponds to 1970. Although wealth and population density vary somewhat between Latin American countries, the region can be considered, as a group, better off than the other underdeveloped regions of the world. The network studied is probably among the best in the region. The paper is addressed to the issue of service-related cost allocation in the actual telephone network of Costa Pica. Although it is theoretically impossible to determine univocally average costs for the different services (due to joint costs), computations are made on the basis of hopefully reasonable assumptions. Marginal costs can be computed univocally, and are computed for long distance links on a dynamic framework, and for urban networks on a comparative-statics framework. Pricing policies are a natural outcome of this study. However, the only price structure that can be computed using only the information included is efficient pricing. Efficient pricing under financial or other constraints requires an understanding of consumer behavior. Among the findings worth mentioning is the interdependence of the cost structure and technological changes. Examples of this are the lesser importance of holding time in common control exchanges vis-à-vis step-by-step, the lesser importance of distance in long-distance traffic in mircowave links vis-à-vis physical pairs. The notable disparity between cost and rates in modern longdistance links, resulting in cross-subsidization from long-distance to urban networks, is a very important issue in most telephone networks. View full abstract»

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  • Behavior of Tandem Buffers with Geometric Input and Markovian Output

    Page(s): 358 - 361
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    A discrete-time system of infinite-capacity buffers in tandem is studied. The input process to the first buffer consists of individual arrivals characterized by a geometric distribution of the time between arrivals; and the probability that the output channel of each buffer, except the last, is transmitting at any epoch depends only on the number of digits in the buffer at that epoch. The transmitting state of the last buffer may depend more generally on the history of that buffer. The analysis shows that in equilibrium, the input processes to the subsequent buffers in the system are geometric with the same parameter as the input process to the first buffer. Therefore, each buffer in the system can be analyzed separately. Furthermore, the equilibrium state probabilities for a given buffer at a given epoch are independent of those for any other buffer in the system at the same epoch. 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