Showing papers on "Broadband networks published in 1987"

Fast switching and fair control of congested flow in broadband networks

Abstract: A new switching architecture is proposed based on the tradeoffs of modern VLSI technology-inexpensive memory and 2-dimensional layout structures. Today, it is economically feasible to preallocate buffer space individually to each virtual circuit in every node, so that "congestion" ceases to have negative effects. On the contrary, when some low-priority circuits offer more traffic than the network can carry, full utilization of the link bandwidth is achieved. In this context, the allocation of bandwidth can be done automatically and in a "fair" way, if packets are multiplexed by circularly scanning all virtual circuits and transmitting one packet from each "ready" circuit. This multiplexing algorithm equally distributes all the available link BW to all the VC's that can use it (other than equal distribution is also possible), while it also guarantees an upper bound for the total packet delay through noncongested VC's (VC's that use less than their share of BW). We present methods for hardware implementation of such fast circular scans, and propose a structure for the switching nodes of such networks, consisting of a cross-bar arrangement like a systolic array that performs merge sorting. It is ideally suited for physical layout on printed-circuit boards or with wafer-scale integration.

Telecommunications in the coming decades

Abstract: The author describes the multimedia services that will evolve from today's public network. The advent of integrated services digital networks, sophisticated switching software, and broadband services is discussed. Field trials in Europe and Japan are described.

Broadband communication and its realization with broadband ISDN

Abstract: In addition to narrowband services, future broadband networks will also include broadband services for applications like: high-speed communication of data, text and graphics person-to-person video communication, access to video information as well as broadcast of programs and data. Low terminal costs and service charges are essential with respect to a growing demand for new services, especially in the home. Broadband ISDN, to be developed on the basis of ISDN and using glass-fiber subscriber lines, will enable a wide range of applications satisfying the needs and requirements of the business and private sectors. The best technical solution from the aspect of user-friendliness and economy is to implement this broadband ISDN for all services with an evolutionary and flexible design. The broadband ISDN concept is not restricted to the public network and terminal equipment but also comprises private networks, information and program centers, etc. Many countries are pursuing the goal of this universal network for the future "information society". However, the approaches for setting up the broadband ISDN differ from country to country, depending on the particular technical and political situation. Standardization plays an important role with regard to "open broadband telecommunication", the worldwide trouble-free communication and information exchange of one party with any other.

A reliable and efficient multicast for broadband broadcast networks

Abstract: A reliable and efficient data transfer protocol is proposed for multicast applications in broadband broadcast networks. The protocol is based on negative acknowledgements, with several enhancements so that it matches most of the functionality of a positive acknowledgement based protocol. The protocol makes the best use of resources in the broadband network environment by conserving processing and trading off transmission and storage resources. The performance of this protocol is compared with the positive acknowledgement based protocol on the basis of maximum throughput as a function of group size for lecture and conference applications.

CMOS VLSI Applications in Broadband Circuit Switching

Abstract: The circuit switching fabric for broadband networks will demand numerous densely interconnected components, with channel rates as high as 150 Mbit/s, This is a natural application area for VLSI, which motivates the evaluation of the key technologies and requirements for realizable broadband circuit and packet switching systems. The critical circuit switching capabilities include the basic crosspoint array, I/O interface between circuit packs, jitter removal and regeneration, and multichannel phase alignment. This paper describes results obtained in these four critical areas. With remote multiplexing units, the greatest constraints are power dissipation and system volume. CMOS circuitry has the advantage here, because of its intrinsic usage-sensitive low power operation. The challenge is to prove that CMOS processes and designs are compatible with the high data and clock rates required of broadband ISDN systems. A fully connected 16 × 16 crosspoint array has been implemented by several laboratories. In this paper we will report on our asynchronous 16 × 16 switching chips fabricated in a 2 μm CMOS process. These devices support channel rates of up to 240 Mbit/s. Crosstalk, jitter accumulation, and power dissipation dominate system issues at the IC interface, making simple CMOS or TTL signaling inappropriate for broadband applications. We will discuss the ECL compatible signaling used in our broadband CMOS IC's. This low noise interface is currently operating at 150-200 MHz rates. We will stress the resulting improvement in noise and jitter accumulation. We will also consider a broader class of low power signaling schemes, including CMOS to GaAsFET direct interfacing. The physical design of switching fabric components will be at least as important as the electronics. Our custom high-density chip carrier and surface mounting arrangement will be discussed, which offers a fourfold reduction in parasitic inductance and capacitance, with corresponding reductions in crosstalk, jitter, and interconnect power dissipation. Pulses normally degrade after passing through asynchronous crosspoint elements. A scalable switching fabric must include regeneration to control this accumulated noise and jitter. We have demonstrated the critical components of such a regenerator, including VCO's, process independent digital phase shifters, phase error detectors, and data relocking circuitry. Existing CMOS technology can support the circuit switching requirements for broadband networks. A thorough understanding of the interface capabilities and requirements will be necessary to deliver functional hardware. The knowledge gained in this work will have direct application to packet switch constraints and performance.

Technology Aspects for System 12 Broadband ISDN

Abstract: Although the enhancement of System 12, SEL's digital switching system, for ISDN services is virtually complete, further development work is being carried out to allow broadband switching for videophone services, videoconferencing, and the distribution of radio and television programs. This paper describes an appropriate approach to the evolution Of System 12 toward the broadband ISDN (B-ISDN), emphasizing the crosspoint and technology aspects of the broadband switch. Test results on a broadband switch VLSI circuit for 140 Mbit/s in a 2μm CMOS technology are presented.

Equipment for through-connecting color television signals

Abstract: Equipment for the through-connection of color television signals between a broadband network BN and video sources and video using equipment including a first video bus VB1 to which a plurality of source connection assemblies QAB1 through QAB3 can be connected with switching sets S1 throgh S3 is provided. A second video bus VB2 to which a plurality of using equipment connection assemblies SAB1 through SAB2 are connected and including a switch-over assembly UB which has input lines L E and output lines L A which are connected to the broadband network BN and are connectible to the video buses through interface switch sets SS1, SS2 and comprising a first interface switch set SS1 which is connected between the input lines and the second video bus and also including a second interface switch SS2 which is connected between the first video bus and the output lines and also including a third interface switch SS3 which is connected between the first video bus VB1 and the second video bus VB2 such that any source of television signals can be connected to any user equipment or sync of television equipments.

Broadband Communications: The Commercial Impact

Abstract: Research carried out by Ovum for its report of the same title, published in 1987, is summarized and updated. The major technologies and commercial applications underlying the development of broadband communications are outlined, and the speed of its introduction is forecast. The picture emerging in the four countries studied here (the United States, United Kingdom, France and West Germany) is one of islands of fiber in major commercial centers. Once these are in place, it will not be too costly to introduce broadband switches, supporting niche applications on an overlay basis. >

Application Of Coherent Optical Techniques To Broadband Networks

Abstract: The potential advantages of applying coherent optical fiber techniques to broadband networks are reviewed, and a number of system types are described to illustrate the operating principles. Particular consideration is given to networks that rely on the use of optically tunable lasers either to define a source frequency or to select a channel from a frequency-multiplexed transmission using the heterodyne receiver technique.

Method for AC voltage coupled transmission of digital signals on metal conductor pairs via connections in each case of differing lengths

Abstract: For non-galvanic transmission of digital signals with bit rates up to and beyond 150 Mbit/s on coaxial pairs in each case via differing lengths, an initial recoding to CMI code is proposed, along with the use of invariable pulse formers at the transmitting and receiving ends which are optimised for a mean cable length and which form receive pulses in such a way that they can assume only a positive or a negative value at sampling times, which change their polarity gradually rather than in jumps, whose passages through the discriminator threshold are situated precisely mid-way between two sampling times and thus overall become immune to changes in the conductor length. The preferred application is a four-wire passive bus for connecting a plurality of terminal devices to the network termination unit of an ISDN broadband network. Applications for star-shaped broadband distribution networks are also possible. With a small coaxial pair, for example, 140 Mbit/s can be transmitted over lengths from 0 to 230 m without individual adapters (Fig. 1).

Broadband Switching System Architecture

Abstract: The architecture, the design concept, and the network organization for NTT's broadband switching system field trials are described. The features of this system are: a variety of connection-type services such as reservation-based and asymmetric connections, the installation of small-size remote concentrating switch, and a system integration using various subscriber transmission media such as optical fiber, satellite, and radio. This paper also presents the system architecture along with a study of the broadband switching system through a close look at the results obtained from field trials.

Architecture of fiber optic broadband interactive distribution system

Abstract: The ideal situation in constructing a broadband communication network is that all kinds of services are provided by a single network. Such a structure is not necessarily advantageous at the present state of technology. From such a viewpoint, the best approach would be first to construct an economically-optimum system, mostly considering the CE type broadband distribution service, which is estimated to have the highest demand, and gradually extend the network for other services. This paper first describes that the configuration combining the star-type subscriber link and the tree-type trunk lines is economical and has the functional expandability. Next another configuration is considered, in which the optical fiber is used for the subscriber link and the frequency division switch is used for the channel selections in the conversion of network topology. It is shown that the system is the optimum from the viewpoint of the cost per subscriber. By applying the notion of the cross-contact switch, it is shown that the proposed system can be extended to the CE type video retrieval service and EE type transmission service. The optical distribution system will be utilized effectively in the future new media, providing the basis for the broadband communication network.

Famnet: an integrated voice and data network

Abstract: The paper describes the design and implementation of the various items of equipment associated with an integrated voice and data network known as FAMNET. The equipment is intended for use with a broadband coaxial cable distribution network. The paper first outlines the mode of operation of broadband networks and this is followed by a description of the user interface to FAMNET. A description of the implementation of an RF modem for use with the network is then presented together with a description of a network monitoring system.

An optimized contention protocol for broadband networks

Abstract: This paper describes the concepts underlying an alternative link-level protocol for broadband local networks. The protocol uses implicit slotting of the contention channel to support larger networks, improve performance, and provide reliable distributed collision recognition without reinforcement. It is designed such that compatible interfaces to existing CSMA/CD-based systems can be provided.

Integrated broadband networks and services of the future

Abstract: The Impact of fiber optics on the design of communication networks and on the potential availability of whole new classes of user services portends another revolution in communications comparable with that brought about by the invention of the transistor.

Rapid Prototyping of Man-Machine Interfaces for Telecommunications Equipment Using Interactive Animated Computer Graphics

Abstract: The concept of Rapid Prototyping can be extended from software development support to simulation of man-machine interfaces This approach will help meeting the challenge imposed on telecommunications engineering by the evolution of an European broadband network system with its subsequent need for highly acceptable user services Animated computer graphics is a cost effective way for introducing simulation into the earliest possible phase of the design cycle

Implementation Of Broadband Integrated Services Distribution Network

Abstract: The issues involved in the design of a broadband integrated services distribution network which utilizes optical fibers in the subscriber loop are considered in this paper. A "hybrid" scheme is proposed which provides integrated access to ISDN and wideband services by delivering voice/data signals in a digital format, while using fan analog format for full motion video services to subscribers. The paper discusses implementation details of the network and provides a cost comparison to alternative options.

Communication system for the tristan accelerators

Abstract: Communication system used for operation of the TRISTAN accerelators consists of a ring network for control computer system, a video information network, and a broadband video/digital data network. In this paper the video information network using optical fiber cables and the broadband CATV and Local Area network are described.