CCITT Recommendations on the ISDN: A Review

This paper gives a brief overview of the I-Series of Recommendations on the integrated services digital network (ISDN) developed by the International Telephone and Telegraph Consultative Committee (CCITT). This set of Recommendations is printed in the CCITT "Red Book." The I-Series Recommendations represent the first major step towards worldwide harmonization of the fast-growing digital network capabilities in support of multiservice (voice, data, and image) user applications. Over 25 different Recommendations set up standard guidelines and features for service capability, network architecture, and user-network interfaces in the ISDN.     

Loop Transmission Aspects of ISDN Basic Access

The status of the formulation of standards for loop transmission to provide Basic Access in the North American loop plant is reviewed. The impact of loop plant bridged taps on performance is discussed, the reasons for preferring echo canceller technology over time compression multiplexing are reviewed, and issues involved in the specification of echo canceller requirements are discussed. This includes line code selection and receiver design, including linear and decision feedback equalizer design. Some of the possible methods of timing recovery are reviewed, and future directions for the evolution of Basic loop access are considered.     

Technology Aspects for System 12 Broadband ISDN

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.     

CCITT error-protection method

The Hamming upper bound is a well known limit for binary codes. Extensions to multilevel codes involve a distinction between whole-digit errors and nearest-value errors. The generalised Hamming bound is derived from consideration of cosets. Application to quaternary and decimal codes are discussed.     

An LSI Implementation of an ISDN Echo Canceller: Design and Network Aspects

This paper describes a single/chip VLSI implementation of aU-interface system component called transceiver with echo cancelling (TEC). The transceiver is implemented with the adaptive echo cancelling method and is combined with a decision feedback equalizer. The algorithms are based on the sign algorithm, but have been considerably improved by using an adaptive reference level. Besides the transceiver functions, functions for activation/deactivation, maintenance, and test are also included in the chip.     

Evolution of ISDN towards broadband ISDN

Worldwide activities to evolve integrated services digital network (ISDN) into an optical-fiber-based universal broadband network have resulted in the first baseline documents, such as CCITT Recommendation I.121. The asynchronous transfer mode has been established as a key element of broadband ISDN (BISDN). The adoption of the G.707-709 recommendations on the new digital transmission hierarchy will also strongly influence further BISDN development. The author presents the current state of the BISDN discussion, especially within CCITT, briefly addressing broadband services and then concentrating on the user-network interface, as its definition is of utmost importance with respect to the introduction of a worldwide unique BISDN. Network scenarios and evolution and interworking aspects of the arising broadband realizations are also addressed     

Theoretical analysis of the ADPCM CCITT algorithm

The unfavorable effects of narrowband inputs on the decoder adjustment when the LMS algorithm is used are analyzed. An explanation is given for the behavior of the CCITT algorithm. Suboptimality of prediction is granted to achieve adjustment, resulting in a satisfactory tradeoff between reduction rate and adjustment. The link between adjustment and uniform stability is enhanced     

Transfer efficiency of the CCITT error-protection method

In this letter, the transfer efficiency of the CCITT V.41 error-protection method is determined, pointing out that it is better at a high error rate and long transmisson block than had previously been estimated.     

CCITT work in teletraffic engineering

The advantages and drawbacks of standardization in TTE (teletraffic engineering) are examined. It is pointed out that the TTE recommendations of CCITT are intended to be international standards. Unlike signaling systems, interfaces, or protocols, the necessity for standardization in this area is not self-evident. However, standardization of grade of service (GOS) definitions, values, and relevant reference conditions seems to be necessary. Support for engineering methods also offers advantages. TTE-related activities in different CCITT study groups try to satisfy many often contradictory demands. Trends in telecommunications strongly support the view that concentration of TTE studies in CCITT would be desirable     

ISDN reaches the market

The integrated-services digital network, for 10 years seen only in limited installations, is branching out around the world. The author describes how telephone carriers are now starting to report a big boost in ISDN installations. He details how the surge is the result of an increasing appetite for bandwidth, a broadening suite of ISDN-enabled applications, wider availability of the network's services, and better prices for service and equipment     

ISDN standardization

The history and achievements of ISDN (integrated services digital network) standardization in the CCITT are reviewed. Two of the most important developments, ISDN basic and supplementary services and broadband ISDN, are focused upon. The underlying concepts in the discussions of ISDN standardization are briefly explained     

ISDN Implementation Stategy of the Deutsche Bundespost--From the ISDN Pilot Project to Commercial Services

The first section of this paper defines the Deutsche Bundespost concept of ISDN, the services to be integrated, and the various ISDN components. The second and third parts of the paper cover the ISDN Pilot project and the offering of commercial ISDN services in the Federal Republic of Germany. The implementation strategy is briefly shown together with some outlook of the integration of broad-band services into ISDN. The last part describes strategic development toward an integrated services universal network, offering all kinds of telecommunication services including individual communication as well as broadcast services such as radio and TV program distribution.     

Personalizing ISDN

It is argued that making integrated services digital networks (ISDNs) more popular among personal computer users is essential for ISDN to prosper. Users in offices, businesses, and at home form a large potential ISDN market. Existing ISDN interface modules such as ISDN adapter boards for personal computers, are limited to ISDN features and can hardly handle the various needs of personal users. An ISDN interface module for personal computers must be designed to handle various applications and provide any-to-any communications. An ISDN personal computer interface developed to handle digital and analog communication protocols and flexibly combine resources is described     

Multi-rate ISDN

Multi-rate integrated services digital network (ISDN) is a new technology for providing dialed-up, circuit-switched, isochronous communications for bandwidths from 128 kb/s to 1.536 Mb/s (DS-1) or 1.920 Mb/s (CEPT-1). Multi-rate ISDN provides a simple way to extend ISDN network services to match the higher bandwidth requirements emerging for videoconferencing, multimedia, imaging, and other high-speed applications. Using this technology, network service providers can offer high-speed connectivity within the boundaries and benefits of existing, circuit-switched, central office and transmission equipment. Only minor changes are required in the operations administration and maintenance and provisioning (OAM&P) procedures associated with multi-rate ISDN, versus existing ISDN transmission and central office maintenance procedures     

CCITT/ANSI voice packetization protocol

This paper introduces the packetized voice protocol G.PVNP/T1.PVP which is being standardized in both the CCITT and T1Y1. At layer 2, G.PVNP/T1.PVP extends the ISDN LAPD protocol to include packetized voice, thereby potentially allowing the integration of voice and data traffic. Layer 3 specifies procedures to deal with voice-band data traffic and to handle channel-associated signalling.