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Communications Magazine, IEEE

Issue 3 • Date March 1999

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Displaying Results 1 - 18 of 18
  • Satellite ATM network architecture [Guest Editorial]

    Page(s): 28 - 29
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    Freely Available from IEEE
  • Tele-learning: The "Killer App"? [Guest Editorial]

    Page(s): 80 - 81
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    Freely Available from IEEE
  • The exciting frontier of lightwave technology [Guest Editorial]

    Page(s): 119
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    Freely Available from IEEE
  • Creating educational Web sites

    Page(s): 109 - 113
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    This article deals with the issue of educators creating their own educational Web sites equipped with original Web-based teaching materials developed by themselves. As an illustrative example, teaching of English as a foreign language in Japan is taken. Several concrete ideas in building up educational Web sites are illustrated, including an example of Web-based rapid reading exercise pages, an example of Web pages implementing instant feedback to students' quiz responses, and semi-automatic creation of students' study history files using standard commercially available software. Introduction of the next-generation Web server, developed at Graz University of Technology, for effective document management and organized access rights control is also discussed View full abstract»

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  • WDM-based packet networks

    Page(s): 130 - 135
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    We discuss design considerations for wavelength division multiplexing (WDM)-based packet networks. In the near term, such networks are likely to consist of WDM links connected using some form of electronic multiplexing. The focus of this article is on the joint design of the electronic and optical layer with the objective of simplifying the network and reducing the protocol stack. To that end, we discuss the benefits of optical flow switching, network reconfiguration, traffic grooming, and optical layer protection. We also discuss the state of all-optical packet networking with particular focus on local area network technology View full abstract»

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  • Modeling and simulation of broadband satellite networks .I. medium access control for QoS provisioning

    Page(s): 72 - 79
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    Broadband satellite networks will play an important role in future integrated services networks. Satellite networks also present unique challenges in system design related to quality of service (QoS) provisioning. In certain system scenarios, medium access control plays a crucial role in the network's ability to deliver a QoS contract. This article focuses on the applications that we envision will utilize future broadband satellite networks, and detail the various system environments which may exist as well as the means by which medium access control protocols can be used to provide QoS. We focus on one system scenario in particular and provide some simulation results on the performance of demand assigned multiple access techniques View full abstract»

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  • WASPNET: a wavelength switched packet network

    Page(s): 120 - 129
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    WASPNET is an EPSRC-funded collaboration between three British Universities: the University of Strathclyde, Essex University, and Bristol University, supported by a number of industrial institutions. The project which is investigating a novel packet-based optical WDM transport network-involves determining the management, systems, and devices ramifications of a new network control scheme, SCWP, which is flexible and simplifies optical hardware requirements. The principal objective of the project is to understand the advantages and potential of optical packet switching compared to the conventional electronic approach. Several schemes for packet header implementation are described, using subcarrier multiplexing, separate wave lengths, and serial transmission. A novel node design is introduced, based on wavelength router devices, which reduce loss, hence reducing booster amplifier gain and concomitant ASE noise. The fabrication of these devices, and also wavelength converters, are described. A photonic packet switching testbed is detailed which will allow the ideas developed within WASPNET to be tested in practice, permitting the practical problems of their implementation to be determined View full abstract»

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  • Medium access control protocols performance in satellite communications

    Page(s): 62 - 71
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    Medium access control protocols are at the core of all forms of electronic communications systems. MAC protocols are designed to coordinate the transmission of packets, retransmission of damaged packets, and resolution of collisions among stations during a contention period. MAC protocols are foundations in low-level network architecture and play a significant role in the performance of higher-level protocols such as multiservices and multimedia application protocols. In this article five classes of MAC protocols are investigated with respect to their applications in satellite communications. These classes include fixed assignments, demand assignment, random access, hybrid random access and reservation, and adaptive protocols. Among several QoS objectives described in high-speed networking and the limitations inherent in satellite communications systems, in this article a set of important performance criteria are identified and used to evaluate different MAC protocols for satellite communications. The performance criteria include high channel throughput, low transmission delay, channel stability, protocol scalability, channel reconfigurability, broadband applicability, and low complexity of the control algorithm. For this, a simulation study is performed among selected MAC protocols from different classes, and their performances have been evaluated for NASA's Mars Regional Network View full abstract»

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  • Web based teaching and learning: a panacea?

    Page(s): 92 - 96
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    Applying the Web to educational purposes is a major field of research nowadays. Discussions in the public arena are largely being led by wild enthusiasm for the far-reaching possibilities offered by this new technology and there appears to be no place for an objective review. Everything seems to be possible, with no limitations in sight. The Web and its applications are seen as the panacea for educational problems. This article is intended to draw attention to some of the limitations and pitfalls inherent in the application of teaching and learning methods based on use of the Web, at the same time taking a step back from the often emotional and poorly informed speculations in the mass media. The article shows actual trends in Web based educational research and tries to plot the location of the front-line as it stands today View full abstract»

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  • Network segment mobility in ATM networks

    Page(s): 38 - 45
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    This article describes the extension of the ATM PNNI v.1 protocol to support the mobility of ATM network segments, consisting of one or more ATM switches, relative to a fixed ATM infrastructure. An application scenario involving an ATM network onboard an aircraft in flight that maintains ATM connectivity via satellite with the ground network is adopted for illustrative purposes. While both routing and handover are key elements necessary to provide mobility, the current work addresses only the former. The article concludes with a discussion of the advantages and limitations of the proposed approach View full abstract»

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  • Traffic management for TCP/IP over satellite ATM networks

    Page(s): 56 - 61
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    Several Ka-band satellite systems have been proposed that will use ATM technology to seamlessly transport Internet traffic. The ATM UBR, GFR, and ABR service categories have been designed for data. However, several studies have reported poor TCP performance over satellite ATM networks. We describe techniques to improve TCP performance over satellite ATM networks. We first discuss the various design options available for TCP end systems, IP-ATM edge devices, as well as ATM switches for long-latency connections. We discuss buffer management policies, guaranteed rate services, and the virtual source/virtual destination option in ATM. We present a comparison of ATM service categories for TCP transport over satellite links. The main goal of this article is to discuss design and performance issues for the transport of TCP over UBR, GFR, and ABR services for satellite ATM networks View full abstract»

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  • Protocol architectures for satellite ATM broadband networks

    Page(s): 46 - 54
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    The latest developments and experimentation in asynchronous transfer mode (ATM) technology show that ATM will be a candidate transport mechanism in many private and public multimedia networks. Furthermore, the interest in satellite ATM systems has grown considerably because they can rapidly and economically extend the boundaries of any terrestrial network. Currently, there is a huge increase in the demand for satellite communications operating at the Ka-frequency bands; several different systems have been proposed and are under development worldwide. Two main scenarios for satellite access network protocols are presented in this article. The first one uses ATM cell encapsulation and satellite-specific protocols for establishing and managing a connection, whereas the second one provides a highly integrated solution with the ATM protocol stack and defines a new satellite ATM (S-ATM) protocol layer View full abstract»

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  • Applications of computer communications in education: an overview

    Page(s): 82 - 86
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    Applications of computer communications can be used in many ways in education. An overview is given of a number of categories of computer communications applications in learning-related activities. Particular attention is given to a new type of system called a course-support environment. In this type of system a database is integrated with Web-based tools and applications, and used to generate a course-support environment accessed via a standard Web browser. Some examples are given. The article moves on to an overview of various issues confronting the acceptance of computer communication systems in educational settings, and indicates some of the ways in which computer communications engineers will have to deal with those issues View full abstract»

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  • Interactive multimedia communication systems for next-generation education using asymmetrical satellite and terrestrial networks

    Page(s): 102 - 106
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    We propose a new concept of a hierarchical network structure for remote education. This system combines broadband satellite networks and simple terrestrial communication networks effectively to meet the demands of point-to-multipoint communications. Remote education experiments have been conducted using the proposed satellite communication networks. The results of network characteristics and degree of satisfaction are discussed. Acceptable communication quality was achieved ensuring an interactive lecture environment View full abstract»

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  • ATM and wireless experiments for remote lectures

    Page(s): 98 - 101
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    We examine our remote lecture experiments using ATM and UNII wireless devices. We discussed which functions should be improved in the current distance-learning system. The Unlicensed National Information Infrastructure/Shared Unlicensed Personal Radio Network (UNII/SUPERNet) wireless devices are introduced for achieving economical distance-learning systems. Two experiments of remote lectures are detailed: a wireless experiment between two buildings in the Philippines and an ATM experiment between Japan and the United States View full abstract»

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  • Next-generation satellite networks: architectures and implementations

    Page(s): 30 - 36
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    A new generation of satellite networks is being developed to handle highly bursty Internet and multimedia traffic. In these networks, satellite links are used for interconnecting remote network segments as well as for providing direct network access to homes and businesses. In this environment, the satellite network must support not only circuit switched traffic, but also packet services with highly bursty traffic patterns. The traditional circuit switched approach based on the user or network signaling is inadequate to carry dynamically varying packet traffic efficiently, necessitating faster bandwidth allocation solutions. Standard interworking solutions and air interfaces are very important for interoperability leading to proliferation of satellite networks to potentially millions of home and business users. In this article we provide an overview of the standardization effort that has started at the TIA in the area of satellite ATM networks. Subsequently, a bandwidth-on-demand multiservice satellite network architecture implementation is described View full abstract»

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  • Building a virtual community for a tele-learning environment

    Page(s): 114 - 118
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    This article presents the results of a research project that requires students and faculty to evolve a virtual community in a university class. The concepts, requirements, and importance of a virtual community are discussed, along with the skill requirements necessary for students to participate effectively in a virtual community. The Web sites and class assignments that form the basis of a virtual community are described. Finally, the importance of enriching the learning experience and humanizing the learning process through the use of a virtual community is also discussed View full abstract»

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  • Online distance education in the United States

    Page(s): 87 - 91
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    Distance education is not a new phenomenon. Correspondence courses have been around for many years. Instructional television is a much newer phenomenon, but we nonetheless have decades of experience. However, currently we are experiencing a “virtual land rush” (some would say “gold rush”) in distance education because of the advent of the Internet. This article examines why this is occurring, provide an overview of online distance education activities in the United States, and present a survey of the relevant technologies and their prospects View full abstract»

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Aims & Scope

IEEE Communications Magazine covers all areas of communications such as lightwave telecommunications, high-speed data communications, personal communications systems (PCS), ISDN, and more.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Sean Moore
Centripetal Networks