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Communications Magazine, IEEE

Issue 9 • Date Sept. 1993

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Displaying Results 1 - 8 of 8
  • SONET implementation

    Page(s): 34 - 40
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    The status of the synchronous optical network (SONET) infrastructure development and deployment are examined to see whether or not they meet original expectations. Issues arising from deployment, such as the use of new features and the necessary support from operations systems, and future directions of SONET are discussed. These future trends include digital cross connect systems (DCSs), SONET ring architectures, and hybrid ring-DCS networks. New SONET services are also discussed.<> View full abstract»

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  • Network synchronization-a challenge for SDH/SONET?

    Page(s): 42 - 50
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    The basic characteristics and requirements of existing networks are summarized, focusing on network synchronization aspects and related parameters. The SDH/SONET-specific pointer-based multiplexing technique is described. It is shown that the need to synchronize the SDH/SONET network elements is not an inherent characteristic of these synchronous networks but rather a result of the generally applied pointer processor implementation. The principles of an advanced pointer processor implementation that is fully compatible with the existing telecommunication environment are outlined. This pointer processor does not require synchronization and, additionally, provides timing transparency. Measurement results demonstrating the feasibility of this approach are presented.<> View full abstract»

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  • Implementing a flexible synchronous network

    Page(s): 52 - 55
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    The SYNET project, undertaken by Deutsche Telekom to modernize its transmission network, is discussed. The SYNET technology is based on the synchronous digital hierarchy (SDH), which uses synchronous transport modules of 155 Mbit/s (STM-1). The latter include a maximum usable bit rate of about 50 Mbit/s as well as a variety of additional information intended for network management. Since the transmission network is divided into several network levels characterized by different traffic loads and structures, a range of synchronous components geared to the requirements of the different network levels have been developed. The major differences between the trunk network and the local networks are described. The implementation of SYNET is reviewed.<> View full abstract»

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  • The impact of G.826 (digital systems error performance)

    Page(s): 56 - 62
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    The International Consultative Committee for Telephone and Telegraph (CCITT) recommendation G.826, the error performance recommendation for digital systems operating at or above the primary rate, is summarized. The relationship between block-based error performance parameters and the bit error rate (BER) is reviewed. The transition from the previous recommendation, G.821, to G.826 is discussed, including a brief statement of the main points found in G.826. The conversion of block-based error performance objectives (EPOs) to BER criteria is discussed in a nonmathematical way. The implications of G.826 and some conclusions are presented.<> View full abstract»

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  • Cost-effective network evolution

    Page(s): 64 - 73
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    The synchronous optical network (SONET) asynchronous transfer mode (ATM) ring architecture called SONET/ATM ring using point-to-point virtual paths (SARPVPs) is discussed. A cost-effective three-phase network evolution path for supporting both the switched and nonswitched DS1 and DS3 services and a possible operations system (OS) evolution path under the proposed three-phase network evolution scenario are described.<> View full abstract»

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  • The European (r)evolution of wireless digital networks

    Page(s): 74 - 82
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    Some of the European developments of two different personal communication services, digital cellular telephony and mobile data networks, are compared with each other and with developments in the United States. The related agendas for research and development of wireless technologies in the past decade are also reviewed and compared. The present status of European cellular telephony, the implementation of mobile data networks in Europe, cellular engineering issues, and economic and regulatory issues are discussed. GSM, the pan-European digital cellular telephony standard, and some essential technology differences between the circuit-switched and packet-switched radio systems and their relative merits in the increasingly competitive European environment are also reviewed.<> View full abstract»

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  • High quality networking of audio-visual information

    Page(s): 84 - 95
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    An overview of low bit rate coding and the interaction between source coding and channel coding is presented. The interaction of coding with networking in a multiuser environment, including algorithms for robust coding which anticipate imperfect network performance, and techniques of decoding a signal that has traversed an imperfect network are described. The performances of such algorithms are illustrated with examples from speech, audio, and video transmission in the presence of packet losses. The challenges in measuring the quality of service (QOS) in the context of new algorithms for coding and networking and the difficulty of measuring QOS in the networking of multimedia information are discussed.<> View full abstract»

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  • FDDI: current issues and future plans

    Page(s): 98 - 105
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    Fiber Distributed Data Interface (FDDI), a set of standards developed by the American National Standards Institute (ANSI) X3T9.5 Task Group, is reviewed. The timed token access method, used to share the medium among stations in this 100-Mbit/s local area network (LAN), differs from the traditional token access method in that the time for the token to walk around the ring is accurately measured by each station and used to determine the usability of the token. FDDI-II, which provides support for isochronous service in addition to the asynchronous and synchronous service provided by FDDI, the media-dependent physical layer (PMD) standard called low-cost fiber PMD (LCF-PMD), and the implementation of FDDI on the synchronous optical network (SONET) are discussed.<> View full abstract»

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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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Centripetal Networks