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Communications Magazine, IEEE

Issue 2 • Date Feb. 2001

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Displaying Results 1 - 17 of 17
  • MPLS: technology and applications [Book Reviews]

    Page(s): 17 - 18
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    Freely Available from IEEE
  • Advances in packet switching/routing in optical networks [Guest Editorial]

    Page(s): 79
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    Freely Available from IEEE
  • QoS and resource allocation in the 3rd-generation wireless networks [Guest Editorial]

    Page(s): 115
    Save to Project icon | Request Permissions | PDF file iconPDF (197 KB)  
    Freely Available from IEEE
  • Software and DSP in radio [Guest Editorial]

    Page(s): 156
    Save to Project icon | Request Permissions | PDF file iconPDF (157 KB)  
    Freely Available from IEEE
  • Metropolitan DWDM: a dynamically configurable ring for the KomNet field trial in Berlin

    Page(s): 106 - 113
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB) |  | HTML iconHTML  

    We present the system concept of a dynamically configurable all-optical add/drop multiplexer for metropolitan wavelength division multiplex rings using dense channel spacing (DWDM). We first outline the essential network requirements. Subsequently, an optical system concept is presented that meets these requirements. In the network elements, innovative all-optical switching technology is employed. Tunable fiber Bragg gratings that perform routing functions by wavelength filtering are discussed in more detail. The system is laboratory-tested. It has been installed in Berlin for a multi-vendor field trial within the German research program “KomNet.” Three optical add/drop multiplexers form a dynamically configurable Metro DWDM ring. Metro DWDM accommodates high bandwidths: a metropolitan ring that provides 0.8 terabit/s ring capacity has been demonstrated. Furthermore, Metro DWDM can provide optically transparent channels enabling the transport of various data formats simultaneously, e.g., SONET/SDH and Gigabit Ethernet. Conversion to a standard format becomes obsolete. The all-optical add/drop multiplexer (OADM) presented provides both manual and dynamic configuration. The system concept of the OADM is developed starting with basic metropolitan DWDM network requirements. The features of the DWDM ring are described, followed by a presentation of the system concept of the flexible OADM. Our focus is on dynamic configuration techniques. Since tunable fiber Bragg gratings are promising components for dynamic optical channel switching, this technology is treated in more detail View full abstract»

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  • Issues for routing in the optical layer

    Page(s): 81 - 87
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    Optical layer control planes based on MPLS and other Internet protocols hold great promise because of their proven scalability, ability to support rapid provisioning, and auto discovery and self-inventory capabilities and are under intense study in various standards bodies. To date however little attention has been paid to aspects of the optical layer which differ from those found in data networking. We study three such aspects which impact routing: network elements which are reconfigurable, but in constrained ways; transmission impairments which may make some routes unusable; and diversity. We conclude that if emerging optical technology is to be maximally exploited, heterogeneous technologies with dissimilar routing constraints are likely. Four alternative architectures for dealing with this eventuality are identified and some trade-offs between centralizing or distributing some aspects of routing are discussed View full abstract»

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  • Smart antennas in software radio base stations

    Page(s): 166 - 173
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    The application of adaptive antenna techniques to fixed-architecture base stations has been shown to offer wide-ranging benefits, including interference rejection capabilities or increased coverage and spectral efficiency. Unfortunately, the actual implementation of these techniques to mobile communication scenarios has traditionally been set back by two fundamental reasons. On one hand, the lack of flexibility of current transceiver architectures does not allow for the introduction of advanced add-on functionalities. On the other hand, the often oversimplified models for the spatiotemporal characteristics of the radio communications channel generally give rise to performance predictions that are, in practice, too optimistic. The advent of software radio architectures represents a big step toward the introduction of advanced receive/transmit capabilities. Thanks to their inherent flexibility and robustness, software radio architectures are the appropriate enabling technology for the implementation of array processing techniques. Moreover, given the exponential progression of communication standards in coexistence and their constant evolution, software reconfigurability will probably soon become the only cost-efficient alternative for the transceiver upgrade. This article analyzes the requirements for the introduction of software radio techniques and array processing architectures in multistandard scenarios. It basically summarizes the conclusions and results obtained within the ACTS project SUNBEAM, proposing algorithms and analyzing the feasibility of implementation of innovative and software-reconfigurable array processing architectures in multistandard settings View full abstract»

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  • Providing quality of service over a shared wireless link

    Page(s): 150 - 154
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    We propose an efficient way to support quality of service of multiple real-time data users sharing a wireless channel. We show how scheduling algorithms exploiting asynchronous variations of channel quality can be used to maximize the channel capacity (i.e., maximize the number of users that can be supported with the desired QoS) View full abstract»

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  • A probabilistic resource estimation and semi-reservation scheme for flow oriented multimedia wireless networks

    Page(s): 135 - 141
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    Currently, multimedia is urgently expected in wireless networks. One of the most important and complicated issues is quality of service guarantees in third-generation wireless networks. The purpose of this article is to propose a probabilistic resource estimation and semi-reservation scheme in considering the probability of real usage made by the mobile host. This scheme can efficiently improve the connection blocking probability, connection dropping probability, and bandwidth utilization View full abstract»

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  • Challenges for MPLS in optical network restoration

    Page(s): 89 - 96
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    Previous standards proposals have focused on extending IP-based MPLS protocols to optical networks. These proposals have concentrated on provisioning optical connections. However, a key expectation of the optical network is that it will offer fast restoration capability, competitive in performance to SONET rings. To meet this expectation, there are key features that need to be added to the current proposals to extend MPLS for the optical network. This article discusses some of these key requirements View full abstract»

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  • Superconductor digital RF development for software radio

    Page(s): 174 - 179
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    We review a new “direct digitization” approach for “digital RF” architectures for software radio. Although direct digitization usually implies the simultaneous digitization of all channels in a particular band at a downconverted IF, we use this term to refer exclusively to the direct digitization of all bands, from near DC to RF. Furthermore, we present results on band selection and digitization of RF signals directly at the carrier frequency with high resolution. These novel approaches are enabled by a superconductor analog-to-digital converter technology using an ultra-fast IC logic known as Rapid Single Flux Quantum (RSFQ) logic, with performance capable of enabling envisioned software radios View full abstract»

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  • Supporting packet-data QoS in next generation cellular networks

    Page(s): 180 - 188
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    In the past few years, the Internet has grown beyond anyone's reasonable imagination into a universal communication platform. At the same time the cellular networks, with their ability to reach a person “anywhere, anytime,” have grown impressively as well. Thus the combination of mobile networks and the Internet into the so called “mobile Internet” promises to be an important technology area. The indications are clear: the cellular networks are rapidly adopting suitable network models for supporting packet data services. A key component of this packet data service model is quality of service (QoS), which is crucial for supporting disparate services envisioned in the future cellular networks. We describe the packet data QoS architecture and specific mechanisms that are being defined for multi-service QoS provisioning in the Universal Mobile Telecommunication Systems View full abstract»

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  • QoS issues in ad hoc wireless networks

    Page(s): 142 - 148
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    Ad hoc wireless networks consist of mobile nodes interconnected by multihop communication paths. Unlike conventional wireless networks, ad hoc networks have no fixed network infrastructure or administrative support. The topology of the network changes dynamically as mobile nodes join or depart the network or radio links between nodes become unusable. This article addresses some of the quality of service issues for ad hoc networks which have started to receive increasing attention in the literature. The focus is on QoS routing. This is a complex and difficult issue because of the dynamic nature of the network topology and generally imprecise network state information. We present the basic concepts and discuss some of the results. The article concludes with some observations on the open areas for further investigation View full abstract»

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  • Resource management and quality of service in third generation wireless networks

    Page(s): 125 - 133
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    The third generation networks and services present opportunities to offer multimedia applications and services that meet end-to-end quality of service requirements. The key parts of the standards are already in place, and limited 3G services have already been turned on. While the evolution to 3G occurs, many operators will implement 2.5G interim solutions for a good period of time. We discuss the various evolution scenarios from the present 2G networks to 3G networks. Then we present the UMTS QoS architecture and its requirements, followed by a discussion on QoS in 3G air interfaces, radio access network, and core network View full abstract»

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  • Radio resource allocation in third generation mobile communication systems

    Page(s): 117 - 123
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    Code-division multiple access has been widely accepted as the major multiple access scheme in third-generation mobile communication systems. Wide-band CDMA and its hybrid associate time-division CDMA are key elements of the IMT2000 framework of standards. Since the beginning of the 1990s there has been enormous research activity in analysis of the soft (i.e., interference limited) capacity of these CDMA-based systems. Optimal usage of the soft capacity to provide, maintain, and guarantee QoS for different service classes is now becoming a very important issue. Therefore, interest in radio resource allocation has recently. This article presents an overview of RRA schemes (primarily for CDMA-based systems) that are flexible, support traffic services with various QoS requirements, minimize call/session blocking and dropping probabilities, and have acceptable radio resource utilization View full abstract»

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  • Optical burst switching for service differentiation in the next-generation optical Internet

    Page(s): 98 - 104
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    In an effort to eliminate the electronic bottleneck, new optical switches/routers (hardware) are being built for the next-generation optical Internet where IP runs over an all-optical WDM layer. However, important issues yet to be addressed in terms of protocols (software) are how to develop a new paradigm that does not require any buffer at the WDM layer, as in circuit switching, and elimination of any layers between which exist mainly due to historical reasons. At the same time, such a paradigm should also efficiently support bursty traffic with high resource utilization as in packet switching. This article surveys design issues related to a new switching paradigm called optical burst switching, which achieves a balance between circuit and packet switching while avoiding their shortcomings. We describe how OBS can be applied to the next-generation optical Internet, and in particular how offset times and delayed reservation can help avoid the use of buffer, and support quality of service at the WDM layer View full abstract»

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  • Evolution toward reconfigurable user equipment

    Page(s): 158 - 164
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    To date, research into reconfigurable mobile communications has predominantly focused on the software radio concept, and specifically on the hardware technologies required to move physical layer processing into a programmable environment. Although an interesting and necessary challenge, this only represents a fraction of the overall support and technology required to realize the potential of the concept. Other necessary developments include network/terminal cooperation for seamless interstandard handoff, QoS management, a secure software download mechanism, terminal software architecture supporting reconfiguration, configuration management, capability negotiation, and so on. Summarizing results from early project deliverables from a European Research project, IST-TRUST (Transparently Reconfigurable Ubiquitous Terminal), this article describes the likely overall system environment and the key technical challenges to be researched for realizing a reconfigurable terminal to meet the needs of users within that environment 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
Osman Gebizlioglu
Huawei Technologies