ISDN protocols for connection control

The technical details of the integrated services digital network (ISDN) access protocols for connection control are described. These protocols are the ISDN physical layer, link layer, and layer 3, which are documented in International Telegraph and Telephone Consultative Committee (CCITT) Recommendations I.430, I.441, and I.451, respectively. Other work that supports or enhances these protocols is described. In particular, the ISDN protocol reference model, how it relates to the open systems interconnection reference model, and CCITT Recommendation Q.932 on service feature control on ISDN are discussed. Possible uses of ISDN, possible evolution paths, and some understanding issues related to ISDN are also described     

Networking of networks: interworking according to OSI

The formal method of interworking networks in accordance with the overall open systems interconnection (OSI) effort being pursued by both the International Organization for Standardization (ISO) and the International Telegraph and Telephone Consultative Committee (CCITT) is described. The problem is introduced, the applicable OSI concepts are defined, and the basic architectural model for interworking and the resulting requirements on protocols, relaying, addressing, and routing are discussed. The problem of interworking from the perspective of the bottom four layers of the reference model (RM)-OSI is approached in a heuristic and informal fashion. The necessary background material is presented using a rigorous set of tools is developed by the work on the RM-OSI. The concepts of interworking are further developed. Conclusions and observations concerning ongoing work are presented     

The evolution of SDH: a view from Telecom New Zealand

The results of a preliminary study of the issues that need to be addressed for introducing SDH (synchronous digital hierarchy) are reported. A brief overview is given of the SDH multiplexing hierarchy adopted by the CCITT (International Consultive Committee for Telephone and Telegraph) and its appropriate subset for use in New Zealand. The capabilities of the various network elements needed to realize an SDH network are described. Examples of possible SDH applications in various parts of the current network are discussed, followed by a view of an evolutionary strategy     

Video compression makes big gains

How new standards for video compression and new IC chips will change the worlds of computing, broadcasting, and communication is discussed. An explanation of how video compression works is given. The three digital video standards that have been proposed are described. They are the Joint Photographic Experts Group (JPEG) standard for still picture compression, the Consultative Committee on International Telephony and Telegraphy (CCITT) Recommendation H.261 for video teleconferencing, and the Moving Pictures Experts Group (MPEG) for full-motion compression on digital storage media. Some available chip sets are described, and the issue of design flexibility is considered     

Advanced intelligent networks: now a reality

This paper looks first at the background to the development of intelligent networking concepts and then tracks this development to the advanced intelligent networks (AINs) of today. The network architecture and basic nodal functions are explained, and a brief review given of the essential intelligent network building blocks, namely the IN (intelligent network) call model and the enhanced CCITT No.7 signalling system. Typical intelligent network services are examined and the tutorial finishes with a review of the latest IN standards     

CCITT standardization of network node interface of synchronousdigital hierarchy

The main concepts and interfacing and multiplexing techniques for an NNI (network node interface) as set forth in CCITT (International Consultive Committee for Telephone and Telegraph) Recommendations are described. The objectives and history of the NNI standardization are reviewed together with concepts, basic requirements, and features of the NNI. The nine-row-based frame structure and the virtual container (VC) concept, which are the main features of the NNI, are introduced. The multiplexing principle and method, the detailed frame structure and overhead, and mapping methods related to the NNI are described. Applications of the NNI in the synchronous network and international interworking are presented. The future application of asynchronous transfer mode (ATM) is discussed     

Management and control of CCSDS cross-support services

A candidate architecture for management and control of Consultative Committee for Space Data Systems (CCSDS) services is presented. An operations concept is presented. Candidate management procedures and a management information base for the resources to be managed are suggested. This architecture is based on concepts of network management of computer and telecommunication networks which are under study by other international standards bodies such as the International Organization for Standardization (ISO) and the International Telephone and Telegraph Consultative Committee (CCITT)     

The ISO reference model entities

The functionalities and presently defined entities at the different levels of the Open Systems Interconnection reference model are discussed. An overview of standards activity by the International Organization for Standardisation (ISO), the Institute of Electrical and Electronics Engineers (IEEE), and the International Consultative Committee for Telephone and Telegraph (CCITT) is given. The ISO reference model and layer functions are described. Standards for the different layers are examined. Network security and naming and addressing issues, which were not covered by the basic reference model and earlier standards activities, are addressed. Two private-sector examples of OSI networks, the Manufacturing Automation Protocol (MAP) and the Technical Office Protocol (TOP), are considered     

Compression and error sensitivity of two-dimensional facsimile coding techniques

Seven proposals were submitted to the International Telegraph and Telephone Consultative Committee (CCITT) for selection of a standard two-dimensional code as an extension of the current CCITT standard one-dimensional code. The CCITT specified the use of particular parameters and procedures to compare the candidate techniques on a quantitative basis. The compression ratio and error sensitivity of all seven coding techniques were measured for a wide range of operational conditions. For example, tests are performed with small K-factors for application to error-prone transmission over switched circuits, and also at infinite K-factor to simulate packet switching networks possessing error control. Particular attention is paid to the error detection/correction procedure to insure that the error sensitivity parameter is as realistic as possible. The essential differences between the seven proposed coding techniques are presented, and the measurement parameters and procedures are reviewed.     

B-ISDN internetworking

The internetworking of broadband integrated services digital networks (B-ISDNs) with metropolitan area networks (MANs), local area networks (LANs), ISDNs, and frame relay networks is examined. The status of some current International Consultive Committee for Telephone and Telegraph (CCITT) recommendations are reviewed     

Intelligent network requirements for personal communicationsservices

It is shown that a moderate set of capabilities within the service switching point (SSP), service control point (SCP), and intelligent peripheral (IP), which are the intelligent network (IN) components directly responsible for the real-time execution and control of end-user services, can engender a wide range of end-user personal communication service (PCS) features. These capabilities could be used as the starting point for an economic analysis of IN implementation costs versus service worth. From a very large target set of call model trigger check points (TCPs), the dozen or so identified in the CCITT Capability Set 1 are shown to be sufficient. The SCP and IP functional entity actions identified are also sufficient to support PCS core network functions     

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.     

Measurement of data compression in advanced group 4 facsimile systems

The CCITT (Consultative Committee for International Telephone and Telegraph) has defined Group 4 facsimile apparatus as that which transmits an ISO A4 (210 × 297 mm) document over public data networks including Packet Switched Data Networks (PSDN) and Circuit Switched Data Networks (CSDN). Data compression is employed in Group 4 systems to minimize the number of bits required for transmission of a message. CCITT Recommendation T.6 defines the basic Group 4 coding scheme to be a variation of the modified READ code (MRC II) which is the Group 3 coding option. This paper measures the compression of the MRC II algorithm for three different documents at resolutions of 200, 240, 300, 400, and 480 picture elements per inch. The compression measurement was accomplished by means of computer simulation. It was determined that the bits per page measure increases linearly with resolution. Results are presented and conclusions drawn. The Group 4 CCITT Recommendations include a mode of operation known as Mixed Mode where a page is divided into two parts: character-coded information and facsimile-coded information. This paper describes four alternative mixed-mode algorithms and measures the compression of each coding technique for CCITT document number 1. The compression measurements were performed by means of computer simulation. Conclusions are drawn regarding the relative advantages of the four algorithms.     

Performance objectives for ISDN's

THE CONCEPT OF the Integrated Services Digital Network (ISDN) and various aspects of its implementation concerning transmission, switching, subscriber interface and signaling are first briefly reviewed. Approaches to the specification of ISDN performance, currently under consideration of the International Telegraph and Telephone Consultative Committee (CCITT) for standardization, are described. A new parameter, percentage Error-Free Blocks (EFB's), is suggested as an additional measure to be specified at different block lengths. The need for more realistic consideration of the impact of burst errors is highlighted and a procedure is outlined using a specific channel model. Also discussed is the effect of delay when satellite channels are revolved. It is suggested that a joint EFB-delay constraint specification might be useful for network routing internal to ISDN.     

Regulatory Aspects of Digital Communications (Radio Frequency Considerations)

This paper describes the domestic and international rules, regulations, reports, and recommendations that have an impact on the design and operation of digital systems. The emphasis is on the technical and the radio frequency (RF) aspects, but nontechnical and baseband matters are mentioned briefly. Organizations discussed include the International Telecommunications Union (ITU), the International Telephone and Telegraph Consulatative Committee (CCITT), the International Radio Consultative Committee (CCIR), the Federal Communications Commission (FCC), and the Office of Telecommunications Policy/Interdepartment Radio Advisory Committee (OTP/IRAC).     

Frame relaying and the fast packet switching concepts and issues

High-speed networking based on frame relaying and fast packet switching are discussed, and the distinctions between the two technologies are clarified. Some of the recent International Consultative Committee for Telephone and Telegraph (CCITT) standards are examined, and the remaining issues for implementing these services are addressed. Particular attention is given to congestion control issues in ATM (asynchronous transfer mode) and frame relay networks. Some industry implementations are briefly reviewed     

An Idea Turns Into Reality--CCITT Activities on the way to ISDN

This paper traces, in broad terms, how the idea of integration of telecommunication services into one network has evolved in the CCITT. A brief overview of existing telecommunication networks is followed by a review of CCITT activities from 1968 to 1980. It had become evident by 1968 that digital technology would not be restricted to transmission only, but would also intrude into switching, signaling, and the terminal field. The CCITT acknowledged this tendency by setting up a Special Study Group entrusted with the study of all questions related to PCM and the coordination of work going on in other Study Groups in the digital field. By 1980 the first ISDN Recommendation (G. 705) was agreed upon, and activities during 1980-1984, when the ISDN took shape, are related in some detail. The structure of the I-Series Recommendations, all relevant to ISDN matters, is described.     

OAM&P for ISDN basic access DSL based on ANSI physical layerstandards

The operations administration maintenance and provisioning (OAM&P) functions provided by the American National Standards Institute (ANSI) for the following standards are described: T1.601, a 2B1Q-based transmission system at the network side of the NT1; T1.605, the United States version of the International Consultative Committee for Telephone and Telegraph (CCITT) Rec. I.430; and T1.216, for management of the ISDN basic rate physical layer. System life-cycle costs are discussed. These consist of the total of hardware cost, line engineering and installation cost, lifetime maintenance costs, and lifetime operations costs. A complete list of the OAM&P functions provided in the August 1990 draft proposed update to ANSI T1.601 is given together with their motivations. The other standards are only briefly considered. Field experience with ANSI-based maintenance is considered     

Multimedia multipoint teleconference system using the 7 kHz audiocoding standard at 64 kbit/s

The International Telegraph and Telephone Consultative Committee (CCITT) has recommended an algorithm to code wideband speech and music (i.e. 7-kHz audio) with 64 kb/s as an international standard (recommendation G.722). A multimedia multipoint teleconference system using the 7-kHz audio coding standard is discussed. System requirements for teleconferencing are examined, and control procedures for the system are examined. A system using digital leased circuits is presented, and the audio-bridging technique used in this system is discussed