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Communications Magazine, IEEE

Issue 9 • Date Sept. 2002

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Displaying Results 1 - 18 of 18
  • Are engineers really like Dilbert?

    Page(s): 14 - 15
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    First Page of the Article
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  • Packet-Oriented Photonic Networks (Guest Editorial)

    Page(s): 56 - 58
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    Freely Available from IEEE
  • Space-time processing for broadband wireless access

    Page(s): 136 - 142
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (128 KB) |  | HTML iconHTML  

    We present an overview of research activities on space-time coding for broadband wireless transmission performed at AT&T Shannon Laboratory over the past two years. The emphasis is on physical layer modem algorithms such as channel estimation, equalization, and interference cancellation. However, we also discuss the impact of space-time coding gains at the physical layer on throughput at or above the networking layer. Furthermore, we describe a flexible graphical user interface attached to our physical layer simulation engine in order to explore the performance of space-time codes under a variety of practical transmission scenarios. Simulation results for the EDGE cellular system and the 802.11 wireless LAN environment are presented. View full abstract»

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  • Securing your Internet connection: a sequel

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    This author discusses the problem of Internet security. He draws some parallels between spammers trying to trick victims to opt out of their e-mail list in order to obtain information on valid e-mail addresses with so-called social engineering techniques used by security perpetrators. The term social engineering is typically used to describe a human-interactive (the emphasis is on the word human as opposed to computer-based) process that tricks people into violating security policies and procedures to get unauthorized access to protected information exposing security vulnerabilities. The best way to deal with social engineering threats is through creating and enforcing strict security procedures through education and training View full abstract»

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  • Optimization-based congestion control for multicast communications

    Page(s): 90 - 95
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    This article outlines an approach for multicast congestion control based on an economic model that has been successfully applied to unicast congestion control. In this model, congestion signals are interpreted as prices and congestion-controlled sessions as utility maximizing agents. A naive extension of the unicast model fails to achieve a reasonable balance between providing the incentives necessary to promote the use of multicast and ensuring that multicast sessions do not interact too aggressively with unicast sessions. We extend the model by introducing a rational definition of multicast utility. The revised model provides a basis for multicast congestion control protocols that provide incentives to use multicast but are necessarily unfair to unicast traffic. We show, however, that the degree of unfairness can be controlled by appropriately setting a design parameter with a limiting case of strict fairness View full abstract»

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  • Electrical ingress buffering and traffic aggregation for optical packet switching and their effect on TCP-level performance in optical mesh networks

    Page(s): 66 - 72
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    The wide deployment of wavelength-division multiplexing technology and new transmission techniques have resulted in significant increases in the transmission capacity in optical fibers, both in the number of wavelengths and the bandwidth of each wavelength channel. Meanwhile, the fast growth of the Internet demands more data switching capacity in the network in order to deliver high bandwidth to end users. Although the capacity of electronic routers has been increasing consistently in the past, optical switching appears to be a more cost-effective way to switch individual wavelengths. As the bit rate per wavelength channel continues to grow, optical subwavelength switching emerges as a new paradigm capable of dynamically delivering the vast bandwidth WDM offers. This article discusses one of such techniques, namely optical packet switching, and its performance perceived by end users in optical mesh networks. Specifically, our investigation reveals the benefit of using electrical ingress buffering and traffic aggregation to reduce packet-loss rate of optical packet-switched networks. Through simulation experiments, we present an evaluation of the network's TCP-level performance based on the proposed architecture View full abstract»

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  • Wavelength switching components for future photonic networks

    Page(s): 74 - 81
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    This article provides a review of integrated laser and semiconductor optical amplifier components that have been configured to provide a variety of all-optical functions such as wavelength conversion, routing, signal regeneration, and add-drop multiplexing. The components have been devised so that they can be reliably and simply used within a multiwavelength network. The article introduces the components by outlining the current leading techniques for wavelength conversion using SOAs, namely by way of cross-gain modulation, cross-phase modulation, and four-wave mixing. The integrated SOA distributed feedback laser is then shown to provide excellent regeneration properties, not only overcoming fiber dispersion limitations but also polarization mode dispersion. Finally, the devices are shown to make possible a regenerative wavelength switching node where routing is achieved using a tunable laser to provide regenerative wavelength conversion followed by an arrayed waveguide router. This switch shows promise for use in future photonic packet switching architectures View full abstract»

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  • Optical packet switching in core networks: between vision and reality

    Page(s): 60 - 65
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    The research on optical packet switching (OPS) has witnessed considerable progress in the 1990s. We examine the future potential of OPS in the core network by discussing this switching approach and the current status of a number of its enabling technologies. Many of these technologies are still in the stage of research and experimentation. We see that optical packet switching may be deployed in the long-term future subject to satisfaction of three main conditions/developments. First, additional technological developments have to take place to overcome remaining implementation challenges while making OPS cost-effective to deploy. Second, a rational migration scenario of the network toward gradual deployment of packet-based optical switching approaches should exist. Finally, carriers have to become more interested in packet-based optical switching solutions View full abstract»

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  • Telephone numbers, domain names, and ENUMbers

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    One of the biggest barriers to the development of public IP telephony services has been the lack of a universal addressing system. While IP-enabled devices have long been capable of originating phone and fax calls, it is difficult to "call" an IP device because they are hard to find. Internet Engineering Task Force (IETF) Request for Comments (RFC) 2916, "E.164 Number and DNS," seeks to solve this problem in a simple and perhaps unlikely way. Simple, in that the ENUM protocol converts existing telephone numbers into domain names.The designers of ENUM hope to foster a global megadirectory of communications users who can be reached in any number of ways by means of only one number. While theoretically any character space could be standardized in an attempt to create a universal addressing scheme, ENUM explicitly adopts telephone numbers, presumably to take advantage of their global user acceptance and mature infrastructure. This choice adds a significant public policy dimension to the story. Far from being benign and boring, telephone numbers can present significant communications policy issues, and are regulated both domestically and internationally. The top level of this hierarchy is defined by International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) Recommendation E.164 View full abstract»

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  • Next-generation mobile satellite networks

    Page(s): 150 - 159
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    Due to the increasing demands of multimedia services supporting high bit rates and mobility, ATM, TCP/IP, and satellite technology are going to be associated to form the internetwork infrastructure of future global systems. In this scenario, distinctions between terrestrial and satellite communications systems, as well as between fixed networks and 3G mobile networks, will cease to exist in a global coverage wireless system. The European Action COST252 actively participated in developing the satellite component of UMTS View full abstract»

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  • Channel islands in a reflective ocean: large-scale event distribution in heterogeneous networks

    Page(s): 112 - 115
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    We discuss the design of a multicast event distribution service intended to support extremely large-scale event distribution. To date, event notification services have been limited in their scope due to limitations of the infrastructure. At the same time, Internet network and transport layer multicast services have seen limited deployment due to lack of user demand (with the exception of streaming services, e.g., on Sprint's US core network and in the Internet II). Research in active networks and reflective middleware suggests a way to resolve these two problems at one go. The goal of this article is to describe a reflective middleware system that integrates the network, transport, and distributed middleware services into a seamless whole. The system integrates this "low-level" technology into an event middleware system, suitable for telemetry, novel mobile network services, and other as yet unforeseen applications View full abstract»

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  • A fourth-generation MIMO-OFDM broadband wireless system: design, performance, and field trial results

    Page(s): 143 - 149
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    Increasing demand for high-performance 4G broadband wireless is enabled by the use of multiple antennas at both base station and subscriber ends. Multiple antenna technologies enable high capacities suited for Internet and multimedia services, and also dramatically increase range and reliability. In this article we describe a multiple-input multiple-output OFDM wireless communication system, lab test results, and field test results obtained in San Jose, California. These are the first MIMO system field tests to establish the performance of MIMO communication systems. Increased capacity, coverage, and reliability are clearly evident from the test results presented in this article View full abstract»

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  • Connection of extruded subnets: a solution based on RSIP

    Page(s): 116 - 121
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    Extruded subnets is the name given to a new type of subnetworks, connected to the Internet through "wideband" residential access lines, such as asynchronous digital subscriber line (ADSL) or cable connections, but seamlessly integrated into their remote corporate network. Extruded subnets are designed to completely hide the fact that they are remote. This article presents the constraints and requirements of extruded networks, and discusses the problems and solutions of their implementation. A new solution is proposed. It is based on IPSec and Realm Specific IP protocol (RSIP), a protocol published as an RFC, mainly as an alternative to Network Address Translating (NAT). An extension is proposed to RSIP in order to improve the scalability of the solution. The use of IPSEC and the extended RSIP satisfies all the requirements for extruded subnets and enjoys excellent scalability. This extruded subnet implementation is now available as open source software View full abstract»

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  • Session-aware popularity-based resource allocation for assured differentiated services

    Page(s): 104 - 111
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    Differentiated services networks are fair in the way that different types of traffic can be associated to different network services, and so to different quality levels. However, fairness among flows sharing the same service, may, not be provided. Our goal is to study fairness between scalable multimedia sessions for assured DS services in a multicast network environment. To achieve this goal, we present a fairness mechanism called session-aware popularity-based resource allocation (SAPRA), which allocates resources to scalable. sessions based on their number of receivers. Simulation results in a scalable and multireceiver scenario show that SAPRA maximizes the utilization, of bandwidth and the number of receivers with high-quality reception View full abstract»

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  • Mobility management in third-generation all-IP networks

    Page(s): 124 - 135
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    It is now widely recognized that using IP as the foundation for next-generation mobile networks makes strong economic and technical sense, since it takes advantage of the ubiquitous installed IP infrastructure, capitalizes on the IETF standardization process, and benefits from both existing and emerging IP-related technologies and services. The large-scale support of data services and their integration with legacy services are the common objectives of all wireless efforts termed third generation (3G) and beyond. In these all-IP wireless networks, IP can be deployed in two modes: the transport mode and the native mode. As we show in this article, this duality in the use of IP has a significant impact on network efficiency and performance. It is the extended native use of IP in the terrestrial segment of a wireless operator's domain that more readily allows for building a converged network with multiple access technologies. We then discuss the different levels of mobility in the all-IP network. In particular, our focus is on micromobility, and on the issue of seamless localized mobility within the converged network. After reviewing the mobility schemes that have emerged in previous years, we describe a hierarchical mobility management scheme based on multiprotocol label switching (MPLS). The scheme employs an enhanced type of MPLS routers, called label edge mobility agents, and is scalable, efficient, and flexible. It directly inherits the noted capabilities of MPLS in terms of support of QoS, traffic engineering, advanced IP services, and fast restoration. This scheme does not use nodes that are specific to any given wireless technology, and is well suited for gradual deployment View full abstract»

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  • Reliable multicast with delay guarantees

    Page(s): 96 - 102
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    The reliable multicast protocol guarantees that all receivers place the source messages in the same order. We have changed this protocol from an event-driven protocol to a timed protocol in order to also guarantee that all of the receivers have a source message by a deadline. Certain of the control messages that are transmitted by the receivers in this protocol are scheduled to occur at specified times, rather than responding to other messages. This results in short sequences of protocol states that are independent of one another, rather than a protocol machine that is recursive and runs indefinitely. It is easier to prove the properties of these short sequences of events than to prove those of many protocols that have indefinitely long sequences View full abstract»

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  • The role of optical CDMA in access networks

    Page(s): 83 - 87
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    We investigate the possible role of optical CDMA (O-CDMA) in future access networks. We begin with a short review of the O-CDMA technique for those unfamiliar with the technology. Next, we investigate in detail those characteristics of O-CDMA that make it an attractive technology for application in metro access networks: fairness, flexibility, simplified network control and management, service differentiation, and increased security. Although O-CDMA has many favorable attributes, it also has several actual or perceived drawbacks. We discuss the technical, economic, and perception barriers that may have limited the widescale deployment of O-CDMA access networks. We try to determine which of these drawbacks may be surmountable in the near future and which may be true "showstoppers" 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.

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Meet Our Editors

Editor-in-Chief
Sean Moore
Centripetal Networks