136 research outputs found

    Demand for satellite-provided domestic communications services up to the year 2000

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    Three fixed service telecommunications demand assessment studies were completed for NASA by The Western Union Telegraph Company and the U.S. Telephone and Telegraph Corporation. They provided forecasts of the total U.S. domestic demand, from 1980 to the year 2000, for voice, data, and video services. That portion that is technically and economically suitable for transmission by satellite systems, both large trunking systems and customer premises services (CPS) systems was also estimated. In order to provide a single set of forecasts a NASA synthesis of the above studies was conducted. The services, associated forecast techniques, and data bases employed by both contractors were examined, those elements of each judged to be the most appropriate were selected, and new forecasts were made. The demand for voice, data, and video services was first forecast in fundamental units of call-seconds, bits/year, and channels, respectively. Transmission technology characteristics and capabilities were then forecast, and the fundamental demand converted to an equivalent transmission capacity. The potential demand for satellite-provided services was found to grow by a factor of 6, from 400 to 2400 equivalent 36 MHz satellite transponders over the 20-year period. About 80 percent of this was found to be more appropriate for trunking systems and 20 percent CPS

    The 30/20 GHz communications system functional requirements

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    The characteristics of 30/20 GHz usage in satellite systems to be used in support of projected communication requirements of the 1990's are defined. A requirements analysis which develops projected market demand for satellite services by general and specialized carriers and an analysis of the impact of propagation and system constraints on 30/20 GHz operation are included. A set of technical performance characteristics for the 30/20 GHz systems which can serve the resulting market demand and the experimental program necessary to verify technical and operational aspects of the proposed systems is also discussed

    Customer premise service study for 30/20 GHz satellite system

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    Satellite systems in which the space segment operates in the 30/20 GHz frequency band are defined and compared as to their potential for providing various types of communications services to customer premises and the economic and technical feasibility of doing so. Technical tasks performed include: market postulation, definition of the ground segment, definition of the space segment, definition of the integrated satellite system, service costs for satellite systems, sensitivity analysis, and critical technology. Based on an analysis of market data, a sufficiently large market for services is projected so as to make the system economically viable. A large market, and hence a high capacity satellite system, is found to be necessary to minimize service costs, i.e., economy of scale is found to hold. The wide bandwidth expected to be available in the 30/20 GHz band, along with frequency reuse which further increases the effective system bandwidth, makes possible the high capacity system. Extensive ground networking is required in most systems to both connect users into the system and to interconnect Earth stations to provide spatial diversity. Earth station spatial diversity is found to be a cost effective means of compensating the large fading encountered in the 30/20 GHz operating band

    Investigation of the tolerance of wavelength-routed optical networks to traffic load variations.

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    This thesis focuses on the performance of circuit-switched wavelength-routed optical network with unpredictable traffic pattern variations. This characteristic of optical networks is termed traffic forecast tolerance. First, the increasing volume and heterogeneous nature of data and voice traffic is discussed. The challenges in designing robust optical networks to handle unpredictable traffic statistics are described. Other work relating to the same research issues are discussed. A general methodology to quantify the traffic forecast tolerance of optical networks is presented. A traffic model is proposed to simulate dynamic, non-uniform loads, and used to test wavelength-routed optical networks considering numerous network topologies. The number of wavelengths required and the effect of the routing and wavelength allocation algorithm are investigated. A new method of quantifying the network tolerance is proposed, based on the calculation of the increase in the standard deviation of the blocking probabilities with increasing traffic load non-uniformity. The performance of different networks are calculated and compared. The relationship between physical features of the network topology and traffic forecast tolerance is investigated. A large number of randomly connected networks with different sizes were assessed. It is shown that the average lightpath length and the number of wavelengths required for full interconnection of the nodes in static operation both exhibit a strong correlation with the network tolerance, regardless of the degree of load non-uniformity. Finally, the impact of wavelength conversion on network tolerance is investigated. Wavelength conversion significantly increases the robustness of optical networks to unpredictable traffic variations. In particular, two sparse wavelength conversion schemes are compared and discussed: distributed wavelength conversion and localized wavelength conversion. It is found that the distributed wavelength conversion scheme outperforms localized wavelength conversion scheme, both with uniform loading and in terms of the network tolerance. The results described in this thesis can be used for the analysis and design of reliable WDM optical networks that are robust to future traffic demand variations

    Campus Telecommunications Systems: Managing Change

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    The purpose of this book is to provide a broadbased understanding of the rapidly changing environment of campus telecommunications. The anticipated audience for this material is the non-technical university administrator who may not have direct responsibility for telecommunications, but has a need to understand the general environment in which his telecommunications manager functions and the basic concepts of the technology. Five topic areas were selected that best cover the preponderance of issues. No attempt has been made to associate or closely coordinate materials from one chapter\u27s subject to that of any other. Each chapter generally stands alone. In total, however, the five chapters address the topics and issues that most often generate inquiries from university administrators outside the telecommunications department. Introduction 1 The Changing Telecommunications Environment 2 Telecommunications Technology and the Campus 3 Student Services 4 Financing a New Telecommunications System . 5 Selecting a Consultant Glossary Inde

    Planning assistance for the 30/20 GHz program, volume 1

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    Functional requirements for the 30/20 GHz communication system, planning assistance for the 30/20 GHz program, and a review of specified conceptual designs and recommendations are provided

    Call admission and routing in telecommunication networks.

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    by Kit-man Chan.Thesis (M.Phil.)--Chinese University of Hong Kong, 1994.Includes bibliographical references (leaves 82-86).Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Overview of Integrated Service Digital Networks --- p.1Chapter 1.2 --- Multirate Loss Networks --- p.5Chapter 1.3 --- Previous Work --- p.7Chapter 1.4 --- Organization --- p.11Chapter 1.5 --- Publications --- p.12Chapter 2 --- Call Admission in Multirate Loss Networks --- p.13Chapter 2.1 --- Introduction --- p.13Chapter 2.2 --- Two Adaptive Routing Rules --- p.15Chapter 2.3 --- Call Admission Policies --- p.17Chapter 2.4 --- Analysis of Call Admission Policies --- p.25Chapter 2.4.1 --- "The CS, LO, GB and the EB Policies" --- p.25Chapter 2.4.2 --- The DP Policy --- p.29Chapter 2.5 --- Performance Comparisons --- p.32Chapter 2.6 --- Concluding Remarks --- p.35Chapter 3 --- Least Congestion Routing in Multirate Loss Networks --- p.41Chapter 3.1 --- Introduction --- p.41Chapter 3.2 --- The M2 and MTB Routings --- p.42Chapter 3.2.1 --- M2 Routing --- p.43Chapter 3.2.2 --- MTB Routing --- p.43Chapter 3.3 --- Bandwidth Sharing Policies and State Aggregation --- p.45Chapter 3.4 --- Analysis of M2 Routing --- p.47Chapter 3.5 --- Analysis of MTB Routing --- p.50Chapter 3.6 --- Numerical Results and Discussions --- p.53Chapter 3.7 --- Concluding Remarks --- p.56Chapter 4 --- The Least Congestion Routing in WDM Lightwave Networks --- p.60Chapter 4.1 --- Introduction --- p.60Chapter 4.2 --- Architecture and Some Design Issues --- p.62Chapter 4.3 --- The Routing Rule --- p.66Chapter 4.4 --- Analysis of the LC Routing Rule --- p.67Chapter 4.4.1 --- Fixed Point Model --- p.67Chapter 4.4.2 --- Without Direct-link Priority --- p.68Chapter 4.4.3 --- With Direct-link Priority --- p.72Chapter 4.5 --- Performance Comparisons --- p.73Chapter 4.6 --- Concluding Remarks --- p.75Chapter 5 --- Conclusions and Future Work --- p.79Chapter 5.1 --- Future Work --- p.8
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