S. Weinstein

The history of orthogonal frequency-division multiplexing [History of Communications]

Orthogonal frequency-division multiplexing (OFDM) is one of those ideas that had been building for a very long time, and became a practical reality when the appearance of mass market applications coincided with the availability of efficient software and electronic technologies. This article describes the background and some of the striking early development of OFDM, with explanation of the motivations for using it. The author presume a broad definition of OFDM as frequency-division multiplexing (FDM) in which subchannels overlap without interfering. It does not not necessarily require the discrete Fourier transform (DFT) or its fast Fourier transform (FFT) computational method.

Echo cancellation in the telephone network

Most long-distance telephone connections generate echoes, which must be heavily attenuated in order to obtain satisfactory transmission quality. Voice-actuated switches (echo suppressors) are widely used to eliminate echoes but have an unfortunate tendency also to cut out part of the desired signal from the other end of the line. Because the distortion caused by echo suppressors is particularly noticeable on satellite-routed connections, the advent of telephone communication via satellite, including the recent introduction of satellite circuits into the U.S. domestic network, has motivated the search for a better way to eliminate echoes. The answer may be the echo canceler, an adaptive filter which selectively eliminates echoes. Advanced echo canceler designs have been undergoing field trials in recent years. This article explains why echo cancelers are advantageous and how they work.

Distributed object technology for networking

Distributed object systems have become a foundation technology and operational platform for large, complex communications networks. This article explains what distributed object technology is and what it does for networks and communication services. It describes the current key technologies in this field, the Common Object Request Broker Architecture (CORBA) and the Distributed Component Object Model (DCOM), and gives examples of networking architectures, such as TINA and TMN, that utilize these technologies. Finally, this article introduces a simplified model for a CORBA-based networking architecture that facilitates open network interfaces and provides a generic platform for services of the future.

Emerging telecommunications needs of the card industry

THE CARD INDUSTRY offers a wide range of payment system products and services, including credit and charge cards, automatic-teller machine networks, interchange networks, debit card systems, authorization and processing services, and point-of-sale equipment. The trend in the industry is to extend automation in the forms of both on-line and off-line transactional systems to a vastly increased number of points of sale and to personal terminals in business and home locations. To this end, the industry is increasingly interested in interchange among proprietary and industry networks, traffic concentration and other facilities sharing arrangements, conversion of voice traffic to data traffic, use of cable television and other local-loop bypass options, integration of public packet-switched networks with private networks, and enhanced transactional security and authentication.

Virtual networks in the Internet

Selective treatments are needed for different types of traffic and different user groups, even on the Internet. Virtual networks provide capabilities for custom routings, priorities, and processing that are not available in either integrated services or differentiated services. This paper relates virtual networks to public network concepts of traffic grooming, virtual private networks and virtual paths, and shows how these and broader capabilities may be realized on the Internet. It describes a networking strategy incorporating intelligent routers that can decouple application QoS needs from core network resource allocations. These routers can be programmed to provide virtual networks, which can satisfy a wide range of application requirements.

Virtual Networks for Customizable Traffic Treatments

Selective treatments are needed for different types of traffic and different user groups, even in the Internet. Virtual networks can help to partition physical network resources, where the resulting partitions may implement their own, independent control and processing mechanisms. This allows for customizable traffic treatment that is not available in either Integrated Services or Differentiated Services. This paper describes a networking strategy incorporating intelligent routers that implements the gateway between the end-user and the core (virtual) network. Intelligent routers classify end-user traffic and assign it to virtual networks provided by the core network, according to a programmable policy. Furthermore, an intelligent router may process transmitted data, according to QoS needs of the application and the core network’s resource allocation, as well as in support of higher-level application functionality. Open, CORBA-based interfaces allow for control of the intelligent router, including dynamic download of code which is used to extend the router’s functionality on the fly, as new applications or user requirements need to be supported.

A CORBA based architecture for QoS-sensitive networking

We describe an architecture, based on the common object request broker architecture (CORBA), for the communication support of quality of service (QoS) sensitive networked multimedia applications. Shared by both control and management entities, this architecture smoothly integrates real-time QoS oriented communication services, such as those offered now or planned for the future in the public network, with everyday services of the Internet. A prototype system is presented which features virtual interfaces that pass QoS information in both directions between a network and an end system, a domain resources manager for maintaining network control policies, and a streams architecture, as an example of a virtual service that facilitates rapid service deployment.

The wired/wireless, instant access, data, and media trial at IEEE NOMS 2000

The networking infrastructure provided at the IEEE NOMS 2000 conference in Honolulu in April 2000 was a field trial of new electronic technologies and services for hotels, conference centers, and meeting events. Its essential elements were immediate and transparent network access, both wired and wireless physical access, and media services including an online database of keynote presentations, proceedings papers, and audio/visual multicasts. This article introduces the services concepts, the technology behind them, and the lessons learned from the NOMS 2000 field trial.

FIRST COMSOC CORPORATE-SPONSORED "WEBINAR" HELD THIS SPRING

multiple access (O-CDMA) system. William Uliasz described the current transformation of the metropolitan transport platform, combining wavelength-division multiplexing (WDM), packet, and time-division multiplexing (TDM) technologies in a “wavelengthcentric” network, and offered perspectives on the metropolitan and access architectures pursued by his company. As in panel sessions at face-to-face conferences, each panelist gave a 15minute presentation, followed by questions and answers with the audience after all speakers had finished. The panelists and moderator were on a voice bridge and could talk freely with one another. The full audio/visual presentations are archived and available through the “Webinars” button on the ComSoc Web site (http://www.comsoc.org), together with files of the individual slide presentations. Announcements and registration for future webinars will also be displayed at this location.