ANNEX (to Questions dealing with broadband aspects) CONTENTS Foreword Part I - Basic considerations Part II - Service aspects Part III - Network aspects Part IV - Items for further studies FOREWORD During the study period 1985-1988 the Broadband Task Group (BBTG) conducted initial studies on broadband aspects of ISDN (B-ISDN). As a result of these studies the following two documents were produced: - Recommendation I.121 on broadband aspects of ISDN; - the present status report on broadband aspects of ISDN. The Recommendation contains a description of the main underlying principles which will form the basis of B-ISDN. These principles are expected to be retained during future activities. The status report includes the information in the Recommendation and a large amount of text reflecting the discussions that have taken place. The information in this status report will form the basis for the future activities of the various Study Groups in the field of broadband aspects of ISDN. PART I - BASIC CONSIDERATIONS Contents 1. General 2. Principles of B-ISDN 3. Evolution to B-ISDN * * * 1. General Considering (a) that effective microelectronic devices for different functions such as analogue-to-digital conversion, video coding, and high speed signal multiplexing are already available and that developments in microelectronics are progressing so rapidly that even signal processing at extremely high bit rates will soon be possible at lower costs; (b) that developments in transmission technology suggest that efficient transportation of very high bit rates on an economical basis is imminent; (c) that the concept of service integration in one unique and universal network is, for cost reasons, the major objective and the general long- term goal world-wide of all administrations; (d) that developments in the fields of information technology, telecommunications technology and electronics for entertainment which are taking place still more or less independently are rapidly emerging. This applies especially to: -possibilities of information technology involving the use of digital image and video processing, promising very highly sophisticated facilities for local use, -digital video and audio signal processing implemented under the TV service providers' and TV systems operators' responsibility, -the definition of telecommunication needs based on the exchange of image and video type information; (e) that a demand for entertainment services such as TV and sound programme distribution seen from the perspective of an extended offer to the customers can clearly be recognized; (f) that present telecommunication systems compared with "natural communication" only allow a minimum of communication between individuals; (g) that a need for additional communication means in the business sector, for example high-speed data transmission for different applications, information retrieval services and transmission requirements for highly sophisticated documents containing text, graphic and image information and possible voice and picture annotation can be identified, and that furthermore, some of these applications may well be of interest to private customers as well; and taking into account (h) that some administrations have already started activities for meeting an initial demand for broadband services; (i) that adherence to OSI, which is considered to be a major goal of future developments in telecommunications and information technology and which is indispensable for profitable use of telecommunication facilities; CCITT/Study Group XVIII decided to initiate studies in the field of broadband aspects of ISDN. 2. Principles of B-ISDN The main feature of the ISDN concept is the support of a wide range of audio, video and data applications in the same network. A key element of service integration for ISDN is the provision of a range of services using a limited set of connection types and multipurpose user-network interfaces. In the context of this Recommendation, the term B-ISDN is used for convenience in order to refer to and emphasize the broadband aspects of ISDN. The intent, however, is that there is one comprehensive notion of an ISDN which provides broadband and other ISDN services. B-ISDN support both switched and non-switched connections. Connections in a B-ISDN support both circuit-mode and packet-mode services. A B-ISDN will contain intelligence for the purpose of providing service features, maintenance and network management functions. This intelligence may not be sufficient for some new services and may have to be supplemented by either additional intelligence within the network, or possibly compatible intelligence in the user terminals. A layered structure should be used for the specification of the access protocol to a B-ISDN. It is recognized that ISDNs may be implemented in a variety of configurations according to specific national situations. 3. Evolution to B-ISDN 3.1 Target transfer mode Asynchronous transfer mode (ATM) is the target transfer mode solution for implementing a B-ISDN. It will influence the standardization of digital hierarchies and multiplexing structures, switching and interfaces for broadband signals. Asynchronous transfer mode ATM is used in this Recommendation as addressing a specific packet oriented transfer mode using asynchronous time division multiplexing technique: the multiplexed information flow is organized in fixed size blocks, called cells. A cell consists of a user information field and a header; the primary role of the header is to identify cells belonging to the same virtual channel on an asynchronous time division multiplex. Cells are assigned on demand, depending on the source activity and the available resources. Cell sequence integrity on a virtual channel is preserved by the ATM layer. ATM is a connection-oriented technique. Header values are assigned to each section of a connection when required and released when no longer needed. The connections identified by the headers remain unchanged during the life time of a call. Signalling and user information are carried on separate virtual channels. ATM will offer a flexible transfer capability common to all services, including connectionless services. 3.2 Evolution steps B-ISDN will be based on the concepts developed for ISDN and may evolve by progressively incorporating additional functions and services (e.g. high quality video applications). The deployment of B-ISDN may require a period of time extending over one or more decades. Thus arrangements must be developed for the interworking of services on B-ISDN and services on other networks. In the evolution towards a B-ISDN, digital end-to-end connectivity will be obtained in part via plant and equipment used in existing and planned networks, such as digital transmission and switching. Relevant Recommendations for these constituent elements of a B-ISDN are contained in the appropriate series of Recommendations of CCITT and of CCIR. In the early stages of the evolution of B-ISDN, some interim user- network arrangements (e.g. combinations of Synchronous Transfer Mode (STM) and ATM techniques) may need to be adopted in certain countries to facilitate early penetration of digital service capabilities. PART II - SERVICE ASPECTS Contents 1. Classification and application of ISDN broadband services 2. Description of broadband services 3. Coding of video signals 4. User-to-network interface from the service point of view Appendix 1 - Possible broadband services in ISDN Appendix 2 - Description of possible applications supported by broadband services Appendix 3 - Descriptions of examples of broadband services Appendix 4 - Examples of high layer functions of audio visual services, e.g. videoconference Appendix 5 - Framework for the study of important ATM Service Parameters Appendix 6 - Bit rates for moving picture qualities Appendix 7 - Services required by different customer categories * * * 1. Classification and application of ISDN broadband services The principles of services supported by an ISDN are described in the I.200-Series Recommendations. The description of ISDN broadband services is based on the principles of the existing Recommendations. 1.1 Introduction This paragraph describes the classification of broadband services, the definition of those service classes, and gives examples of services in each service class proposed to be supported by the ISDN. This classification does not take into account the location of the implementation of the functions either in the network or in the terminals. This classification is primarily from the point of view of the network and not from the user point of view. Depending on their communication functions and applications, the services to be supported by the B-ISDN may be standardized and offered by the administration as teleservices or bearer services. 1.2 Service classes Depending on the different forms of the future broadband communication and their applications, two main service categories have been identified: interactive services and distribution services. The interactive services may be subdivided into three classes of services, viz., the conversational services, the messaging services and the retrieval services. The distribution services are represented by the class of distribution services without user individual presentation control and the class of distribution services with user individual presentation control. 1.3 Definitions of service classes 1.3.1 Conversational services Conversational services in general provide the means for bidirectional dialogue communication with real-time (no store-and-forward) end-to-end information transfer from user to user or between user and host (e.g. for data processing). The flow of the user information may be bidirectional symmetric, bidirectional asymmetric and in some specific cases (e.g. such as video surveillance), the flow of information may be unidirectional. The information is generated by the sending user or users, and is dedicated to one or more individual communication partners at the receiving site. Examples of broadband conversation services are videotelephony, videoconference and high speed data transmission. 1.3.2 Messaging services Messaging services offer user-to-user communication between individual users via storage units with store-and-forward, mailbox and/or message handling (e.g. information editing, processing and conversion) functions. Examples of broadband messaging services are message handling services and mail services for moving pictures (films), high resolution images and audio information. 1.3.3 Retrieval services The user of retrieval services can retrieve information stored in information centres and in general provided for public use. This information will be sent to the user on his demand only. The information can be retrieved on an individual basis. Moreover, the time at which an information sequence is to start is under the control of the user. Examples are broadband retrieval services for film, high resolution image and audio information. 1.3.4 Distribution services without user individual presentation control These services include broadcast services. They provide a continuous flow of information which is distributed from a central source to an unlimited number of authorized receivers connected to the network. The user can access this flow of information without the ability to determine at which instant the distribution of a string of information will be started. The user cannot control the start and order of the presentation of the broadcast information. Depending on the point of time of the user's access, the information will not be presented from its beginning. Examples are broadcast services for television and audio-programmes. 1.3.5 Distribution services with user individual presentation control Services of this class also distribute information from a central source to a large number of users. However, the information is provided as a sequence of information entities (e.g. frames) with cyclical repetition. So, the user has the ability of individual access to the cyclical distributed information and can control the start and order of presentation. Due to the cyclical repetition the information entities, selected by the user will always be presented from its beginning. One example of such a service is full channel broadcast videography. 1.4 Examples of broadband services to be considered Appendix 1 contains examples of services, their applications, and some possible attribute values describing the main characteristics of the services. Descriptions of some possible applications are contained in Appendix 2. 2. Description of broadband services 2.1 The static description of broadband bearer services and teleservices is based on the service descriptions by attributes in Recommendation I.210. The proposed attributes and attribute values for the description of broadband bearer services and broadband teleservices are listed in Appendix 3. A format to be used for prose definition and description of broadband services is also contained in Appendix 3. 2.2 Descriptions of examples of broadband bearer services and teleservices using the above prose description format and attributes and attribute values are given in Appendix 3. Services described include: - broadband bearer services; - high quality videotelephony services; - high quality videoconference services; -coexisting quality and high definition television distribution services; - broadband Videotex services. 2.3 Further study of the high layer attributes is required. Some examples of high layer functions of audio-visual services, which could be described by attributes, are given in Appendix 4. 2.4 The study of services supported by ATM requires concentration on a number of key parameters for key services. Appendix 5 contains a framework for such a study. 3. Coding of video signals The information transfer capabilities for the various broadband picture services so far identified will be dependent on the Quality of Service to be offered. This should be taken into account when establishing an assessment of the information transfer capabilities to be supported by the broadband network. Up to now the opinions on the quality relationships of video services vary considerably. The main reasons for this are: a) Markets for different customer categories (e.g., residential, small, medium and large business customers) have different requirements. A trade-off between cost and quality is involved. This need for a range of qualities for the various markets will require that studies be carried out into interworking between services having different qualities. b) It is evident that the quality associated with some services will change over the coming years. This applies, for example, to TV- services where new technologies for cameras and displays for MAC and HDTV presentation will enable high-quality pictures to be economically provided. The technology for this level of quality is not mature but the large potential market may stimulate its development, so products will probably be available within the relevant time-scales. As a result of this trend, the quality that a service should provide is still the subject of discussion. Appendix 6 provides an up-to-date review of current expectations in picture-coding techniques; it clearly indicates that the information transfer capabilities needed for picture services could be significantly reduced in a certain range without affecting the picture quality. The degree of reduction anticipated for moving pictures is presented in the table where "uncompressed" and "compressed" bit rates for different quality classes are given. As far as "uncompressed" bit rates are concerned, it should be noted that only the value associated with quality class "B" is really a "standard" (CCIR Recommendation 601). 4. User-network interface from the service point of view 4.1 Introduction As a basis for the definition of basic user interface structures of a B- ISDN the service requirements for different user categories should be studied. In the following some results of such studies are reported. 4.2 Customer categories The usual division of the market into residential and business customers is relevant even for broadband services. The category of residential customers can be regarded as reasonably homogeneous for this purpose and there is no reason for a further subdivision. The business customers category, however, has to be further subdivided. This can be done in a number of ways, e.g. with respect to size (number of employees), branch, etc. A subdivision with respect to size has been found to be one way to proceed. The business category is subdivided into three sub-categories, i.e. "small" (less than 5 employees), "medium" (between 5 and 20 employees) and "large" (more than 20 employees). Statistics for business customers indicate roughly that in this respect 90% of all customers are "small" and "medium" and 10% "large". However, the above-mentioned boundaries should not be taken as absolute. In addition, the categories of small, medium, and large business customers will vary from industry to industry, or even country to country. Further, business characteristics, in addition to the number of employees, will influence the requirements of a customer for simultaneous broadband services. For example, additional characteristics could include: -type of product sold: an engineering design company may have more requirements for high quality graphics communications than some other companies; -business territory: a company dealing internationally may have more requirements for videoconferencing than a company dealing only in a local environment; -degree of technology implemented: a company highly computerized may require more high speed, high quality transmission than a non-technical company; -corporate organization: a geographically dispersed organization such as a holding company or government may require more conferencing capabilities than a geographically centralized organization; -corporate characteristics: the level and degree of intra-company communication and rate of technological adoption will partly determine the number of simultaneous broadband services a company will require. 4.3 Service requirements It can be expected that business customers of the sub-category "large" will have very specific service requirements. Moreover, there will be a significant difference between these customers relating to the type of business. In these cases, service requirements can only be fulfilled by the creation of additional solutions. So, the sub-category "large" can be left aside in deriving "basic accesses". There are other undefined aspects of broadband services and therefore undetermined characteristics of the services themselves that will impact the requirements for simultaneous broadband services. These may include: -national or international sources and content of the distributive services; -cost effectiveness of the services offered; -degree of deployment of broadband and consequent accessibility to other businesses, additional services, etc.; -degree of case of use (i.e. user friendliness) of the service offerings, etc. Service requirements should be derived for the remaining categories: "residential", "small business" and "medium business". The requirements are presented in Appendix 7. 4.4 Translation of service requirements to channel requirements The following comments are offered as a basis for discussion. 4.4.1 Video service Video service is one of the most important services in the broadband ISDN. Many variations of this service have been discussed in two categories; communicative service and distributive service. Although the video coding rate or the type of H Channel is different in each variation, typical applications of H Channels can be summarized as follows: -H2: most applications of existing broadcasting TV and quality, such as CATV, videotelephony and videoconference; -H4: high quality video services such as HDTV and EQTV, and contributive video services with studio quality. This classification was brought about by advancements in video coding technology. Video codecs adopting H2 Channel rates with broadcasting TV end quality have already begun to be fabricated into LSIs. They are expected to be the same in quality and cost as linear PCM codecs adopting H4 Channel rates when Recommendations on broadband ISDN are established. Also, high quality video codecs for HDTV and EQTV will be provided at the H4 Channel rate in the near future. 4.4.2 Data transmission Source rates of data information range from the kilo-bit per second region to the hundred mega-bit per second region. Therefore, every channel type can be used for transmitting data signals. A characteristic point of the data application is that a large capacity channel is sometimes subdivided into smaller channels. (Even in 64 kbit/s, ISDN, a B Channel can be subdivided into smaller sub-channels such as 8 kbit/s, 16 kbit/s and 32 kbit/s according to Recommendation I.460). For instance, an H2 Channel will be subdivided into H1 Channels; in this case, a few H2 Channels may be used for video signals, while other H2 and H1 Channels may be used for data signals. Subdivision of high speed channels is very important both for video services and data services. 4.5 Further studies The present status of the study has revealed the difficulty of producing firm and reliable estimates of customer requirements for different services. Not only will this difficulty exist prior to the development of the broadband network but changes in requirements will also create shifting balances in the range of services presented over the network. For these reasons, it is recommended that consideration be given to network interfaces that are flexible and that offer dynamic allocation of resources between different services. Appendix 1 (to Part II/Annex) Possible broadband services in ISDN1 + - + Service Type of Examples of Applications Some possible classes information Broadband services Attribute Values7, 8 + - Conversational Moving pictures Broadband2, 3 Communication for the Demand/reserved/ services (video) and Videotelephony transfer of voice permanent sound (sound), moving Point-to-point/ pictures, and video multipoint scanned still images Bidirectional and documents symmetric/bidirect- between two locations ional asymmetric (person-to-person)3 (Value for informa- Tele-education, tion transfer rate Teleshopping, is under study) Tele-advertising Broadband2, 3 Multipoint communication Demand/reserved/ Videoconference for the transfer of permanent voice (sound), moving Point-to-point/ pictures, and video multipoint scanned still images and Bidirectional documents between two or symmetric/bidirect- more locations (person- ional asymmetric to-group, group-to-group)3 Tele-education, Teleshopping, Tele-advertising Video-surveillance Building security Demand/reserved/ Traffic monitoring permanent Point-to-point/ multipoint Bidirectional asymmetric/ unidirectional Video/audio TV signal transfer Demand/reserved/ information Video/audio permanent transmission dialogue Point-to-point/ service Contribution multipoint Bidirectional symmetric/bidirect- ional asymmetric Sound Multiple sound- Multilingual commentary Demand/reserved/ programme signals channels permanent Multiple programme Point-to-point transfers multipoint Bidirectional symmetric/bidirect- ional asymmetric + - + Appendix 1 (continued) + - + Service Type of Examples of Applications Some possible classes information Broadband services Attribute Values7, 8 + - Conversational Data High speed High speed data services unrestricted transfer (continued) digital infor- LAN interconnection Demand/reserved/ mation transmission Computer-computer permanent service interconnection Point-to-point/ Transfer of video multipoint and other Bidirectional information types symmetric/bidirect- Still image transfer ional asymmetric Multi-site interactive CAB/CAM High volume file Data file transfer Demand transfer service Point-to-point/ multipoint Bidirectional symmetric/bidirect- ional asymmetric High speed tele- Realtime control action Telemetry Alarms Document High speed User-to-user Demand Telefax transfer of text, Point-to-point/ images, drawings, etc. multipoint Bidirectional symmetric/bidirect- ional asymmetric High resolution Professional images image communicat- Medical images ion service Remote games and game networks Document commun- User-to-user transfer Demand ication service of mixed documents4 Point-to-point/ multipoint Bidirectional symmetric/bidirect- ional asymmetric + - Messaging Moving pictures Video mail service Electronic mailbox Demand services (video) and service for the Point-to-point/ sound transfer of moving multipoint pictures and Bidirectional accompanying sound asymmetric/unidirect- ional (for further study) + - + Appendix 1 (continued) + - + Service Type of Examples of Applications Some possible classes information Broadband services Attribute Values7, 8 + - Messaging Document Document mail Electronic mailbox Demand services service service for "mixed" Point-to-point/ (continued) documents4 multipoint Bidirectional asymmetric/unidirect- ional (for further study) + - Retrieval Text, data, Broadband Videotex Videotex incl. Demand services graphics, sound, moving pictures PT-PT still images, Remote education Bidirectional moving pictures and training asymmetric Telesoftware Teleshopping Advertising News retrieval Video retrieval Entertainment Demand/reserved service purposes Point-to-point/ Remote education multipoint and training Bidirectional asymmetric6 High resolution Entertainment Demand/reserved image retrieval purposes Point-to-point/ service Remote education multipoint and training Bidirectional Professional image asymmetric6 communications Medical image communications Document retrieval "Mixed documents" Demand service retrieval from Point-to-point/ information centres multipoint6 archives etc.4, 5 Bidirectional asymmetric Data retrieval Telesoftware service + - + Appendix 1 (continued) + - + Service Type of Examples of Applications Some possible classes information Broadband services Attribute Values7, 8 + - Distribution Video Existing quality TV programme Demand (selection)/ services without TV distribution distribution permanent user individual service (PAL, Broadcast presentation SECAM, NTSC) Bidirectional control asymmetric/ unidirectional Extended quality TV programme Demand (selection)/ TV distribution distribution permanent service Broadcast Enhanced definition Bidirectional TV distribution asymmetric/ service unidirectional High quality TV.. High definition TV programme Demand (selection)/ TV distribution distribution permanent service Broadcast Bidirectional asymmetric/ unidirectional Pay-TV (pay-per- TV programme Demand (selection)/ view, pay-per- distribution permanent channel) Broadcast/multipoint Bidirectional asymmetric/ unidirectional Test, graphics, Document Electronic news- Demand (selection)/ still images distribution paper permanent service Electronic Broadcast/multipoint publishing Bidirectional asymmetric/ unidirectional6 Data High speed Distribution of Permanent unrestricted unrestricted Broadcast digital infor- Data Unidirectional mation distribution service Moving pictures Video information Distribution of Permanent and sound distribution video/audio Broadcast service signals Unidirectional + - Distribution Text, graphics, Full channel Remote education Permanent services with sound, still broadcast and training Broadcast user individual images videography Advertising Unidirectional presentation News retrieval control Telesoftware + - + w Notes to Appendix 1 Note 1 - In this table only those broadband teleservices and bearer services are considered, which may require higher transfer capacity than that of the H1 capacity. Teleservices for sound retrieval, sound main applications and visual services with reduced or highly reduced resolutions are not listed. Note 2 - This terminology indicates that a re-definition regarding existing terms has taken place. The new terms may or may not exist for a transition period. Note 3 - The realization of the different applications may require the definition of different quality classes. Note 4 - "Mixed document" means that a document may contain text, graphic, still and moving picture information as well as voice annotation. Note 5 - Special high layer functions are necessary if post-processing after retrieval is required. Note 6 - Further study is required to indicate whether the point-to- multipoint connection represents in this case a main application. Note 7 - At present packet mode is dedicated to non-realtime applications. Depending on the final definition of the packet transfer mode further applications may appear. The application of this attribute value requires further study. Note 8 - For the moment this column merely highlights some possible attribute values to give a general indication of the characteristics of these services. The full specification of these services will require a listing of all values which will be defined for broadband services in CCITT Recommendation I.2xx. Appendix 2 (to Part II/Annex) Descriptions of possible applications supported by broadband service 1. Face-to-face dialogues between two or more individuals or groups of persons (provided by videotelephony and videoconference services) present moving pictures of the upper part of communication partner's body, at least head and shoulder. By this way in addition to voice facial expressions, gestures and bearing of the communicating user(s) are transferred to the remote partner(s). For this kind of communication lips and voice synchronization is very important. 2. Showing of documents with sketches, diagrams, charts, etc., photographs and slides as "still images" in general accompanied by verbal explanations and comments or as "moving pictures", i.e., with explanation by marking, underlining, or pointing at details with (moving) finger or pencil. The presentation of details require appropriate video-resolution; details also may be zoomed. 3. Drawing of sketches, diagrams, etc., as visual explanations of ideas or events may be done by one or interactively by both partners using videotelephone communication. 4. Presentation of objects: -showing of different views of three-dimensional objects, e.g., by turning the objects; -showing the functionality of objects, e.g., by moving of movable parts of the objects; -giving operating and repair instructions or hints to build objects; -giving working (cooking, baking) instructions; -showing the house, the garden, the new car, etc., using a portable camera. 5. Showing scenes in the home such as playing children, feeding the baby, grandchild playing piano, ... . 6. Playing games with remote partners, e.g., chess. The chess boards will be shown simultaneously to both players via point-to-point videotelephone connections. (The chess boards may also be presented simultaneously or alternatively to an auditorium via videodistribution or videoconference services.) The downloading of video-computer games is a special application of telesoftware, enabling users to execute man/machine type gaming programs on a computerized communications terminal. The requirements for this service would virtually be the same as those discussed above, i.e., entire game packet may be downloaded at once for local off-line execution, or this program may be downloaded in sequential blocks (in a continuous two-way link) for remote execution. However, a significant difference exists between these requirements and those of "Game Networks". The "Game Network" concept goes beyond the person-vs-computer electronic game to a computer-mediated person-vs-person environment. In game networks, a centrally located computer keeps track of contestant's movements and actions during the game. Computer driven video would be part of these games. 7. Videotelephone interviews e.g., as part of a TV program, showing the interview partners and possibly background scenes depending on the interview's topic. 8. Active participation in meetings or TV shows observing the discussions and presentations and giving comment to questions, special topics. 9. Passive looking on special events: meetings, celebrations, traffic scenes. 10. Surveillance/monitoring of objects or scenes such as houses, industrial objects (e.g., power-stations), road traffic, sick persons, playing children, babies. 11. Looking on and identification of people at the front door (when doorbell rings). This application may also be enhanced by showing reference pictures to the observer. 12. Health visiting: Via videotelephony people can consult the doctor, showing him an injury or explaining to him e.g., motion dependent pain, in order to get a tele-diagnosis. 13. Audio-visual tele-education and training: Video-participation -Video-participation in organized lectures in front of an audience in e.g., universities, evening schools; i.e., passive participation by observation (one-way audio-video communication). -Video-participation in lectures offering besides the observations and listening also the possibility to give comments and to answer questions via an audio back-channel. -Active video-participation with bidirectional audio-visual communication: the teacher can hear and see the remote student(s). Remote lecturing/teaching: -The remote teacher gives "video-lessons" to a single student or a group of students. The group of students may be assembled in a conference room. The communication between teacher and student(s) will be performed via point-to-point audio-visual connections. -Video-lessons with a group of students at different locations will be performed via videoconference connections. In both bases bidirectional or unidirectional audio-video communication may take place. 14. Tele-advertising: Product vendors may provide information on their products in the form of still images of audio/video information (films). This product information may be offered via audio/video retrieval and distribution services for general access by potential buyers or via videotelephony as a customer individual presentation. In the latter case a representative of the vendor may show a customer-dedicated selection of the products with special comments and answers to the customer's questions. This application may be enhanced by a freephone facility that the calling customer will only pay local connection charges (in the case of long distance calls). 15. Teleshopping This application contains access to audio, video, still image or other information about a vendor's products (advertising), selection and ordering of special products by the customer possibly with automatic debiting of his account. The orders may be given verbally or typed in via the dialling keys or an alpha-numeric keyboard. 16. Transfer of audio-visual records (film) between users: video clips (short films), home scenes, handling instructions, hobby hints. 17. Visual communication of deaf and dumb persons Depending on the abilities of those handicapped persons the presentation of the finger language, gestures, mimics and/or motions of lips with high temporal and spatial resolution is very essential. 18. Professional image communications Certain professional groups and government departments make heavy use of images (e.g., medical, satellite, police, students/researchers). Most of the requirements of these groups are currently being satisfied using film-based systems which are slow, cumbersome and expensive to handle. Hence, a broadband digital image transmission application, providing access to image data bases is very necessary. 19. Medical image communications Possibly the most obvious example of professional image communications is medical image communications. Indeed, the medical profession makes extensive use of imaging for medical records and diagnosis. X-rays, thermographs, tomograms, ultrasound scans, and nuclear medicine images are typical examples of applications in the medical field. Imaging acquisition systems and image workstations distributed throughout hospitals and remote medical offices could communicate with each other and have access to data bases of digital images and medical records through broadband ISDN. The image resolutions required are different in each case. The difference between digital radiography and other imaging techniques should be highlighted in terms of the number of bits in the digitized images. Each radiograph can generate of the order of 50 to 100 Mbit (say 2000 x 2000 samples quantized at 12 or 14 bits) versus 1 to 14 Mbit for other images (say 320 x 320 or 512 x 512 samples quantized at 12 or 14 bits). More work is required to determine the required resolutions and to develop standards. Of all the imaging techniques mentioned previously, radiology is the one that would produce the larger volume of bits every day. This is because of both the high resolution required for radiographs and the large number of them produced every day in hospitals and radiology clinics. The images in the image-base will be accessed on-demand from the visual workstations. Suppose that the speed of transmission has to be fast enough for sending a complete image in one or two seconds. Intra- hospital workstations may require the fastest access time and remote locations may tolerate longer delays. Consequently, high resolution images (say 1000 x 1000 x 12) would require about 6 Mbit/s or more. Some of the requirements include: Image retrieval: The visual workstation will be used to access the image store, through a telecommunications link, and will present to the viewer a reconstructed image, as selected. Any image could be accessed through ISDN broadband. Image manipulation: Since the resolution of the display may not be sufficient to present to the viewer all the information available in the image at one time, capabilities must be provided to select the intensity range, zoom, pan roll, magnify and reduce to roam through larger images which are stored in a buffer. These features must be easy to use too. The terminal will thus act as a viewing window which can be controlled by the user. Image processing: The image may have not been obtained under ideal conditions (e.g., may be underexposed or overexposed) or it may have to be enhanced before viewing. A number of algorithms may be used to accomplish this, such as intensity mappings, histogram equalization, frequency shaping (e.g., high-pass, band-pass, low-pass filters), tomographic filtering and pseudo colour. It is believed that image processing will have the most dramatic influence in each of the image modalities. Image conferencing: It is often required that two or more doctors discuss the same image for consultation, training, or prior to medical procedures. The ISDN broadband network could provide a common visual space on a number of separate workstations. 20. Telesoftware The sales of prepackaged software by other than physical means appears to be one area offering significant growth potential. This is primarily supported by the fact that at present approximately 90% of the cost of software is for distribution. An electronic software distribution system through broadband ISDN, involves the downloading of remotely stored programs (i.e., from software data bases) to a computerized communications terminal (CCT). A number of benefits would accrue to the user including: -easy/convenient access to a large selection of software packages, e.g., financial, educational, videogames; -potential cost savings (i.e., resulting from cost reductions in distribution); -problems of empty stock are eliminated; -can permit remote execution of software too large for local storage facilities. 21. Video retrieval Video retrieval provides customers with the capability of accessing program sources and data bases of video information at any time and request a specific program channel, a specific video program (e.g., a movie) or combination of programs (e.g., various versions of news on a given topic). The application can have several aspects depending on a number of attributes: Quality: e.g., existing quality TV or high quality TV. Starting time: e.g., fixed and unique time (as in broadcast TV), a number of fixed times per day (as in "pay-TV") which could be at intervals as low as 10 minutes or less, or at any requested time using a dedicated channel to the data base. Control: If the user has a dedicated channel to a data base and has control over the retrieval of the information, the following features are possible: pause, freeze-frame, replay, forward and reverse play, variable play speed, delivery frame by frame (e.g., for searches) rewind and fast forward, scan, search, language selection (similar to movies on airplanes), quit, split screen (to match more than one programme simultaneously). "Customized retrieval" would allow users to request programs according to their desires, possibly by accessing information distributed in several data bases. For example, someone interested in astronomy may wish to see video news reports of an astronomical event from as many sources as possible. Depending on the network resources being used, the specific application would be tariffed accordingly. E.g., access to broadcast information would be much cheaper than access to information from a data base. An application of intermediate capabilities could be "staggered re- broadcast", i.e., access to broadcast information at fixed times later (e.g., every hour during 24 hours). Appendix 3 (to Part II/Annex) Descriptions of examples of broadband services In the service descriptions included in this appendix, the following prose definition and description format, attributes and attribute values have been used. 1. Definition 2. Description 2.1 General description 2.2 Specific terminology 2.3 Applications 3. Procedures 3.1 Provision/withdrawal 3.2 Normal procedures 3.2.1 Activation/deactivation/registration 3.2.2 Invocation and operation 3.2.2.1 Call set-up 3.2.2.2 Possible procedures during the communication phase 3.2.2.3 Call release 3.3 Exceptional procedures 3.3.1 Activation/deactivation/registration 3.3.2 Invocation and operation 3.3.2.1 Failures situations due to the calling party 3.3.2.2 Failures situations due to the called party 3.3.2.3 Failures situations due to the network 3.4 Alternate procedures 3.4.1 Activation/deactivation/registration 3.4.2 Invocation and operation 3.5 Verification 3.6 Quality of Service 4. Network capabilities for charging 5. Interworking requirements 6. Possible supplementary services. TABLE 1 Service attributes and possible attribute values for broadband bearer services (Note 7) + + Attributes Possible Attribute Values + + - Information transfer attributes + + - STM ATM ATM 1. Information transfer mode (Circuit) Deterministic Statistical Packet Note 11 Note 11 + + - + - 2. Information transfer rate Bit rate Mbit/s Throughput Note 9 + - + - 2.1 Peak bit rate FS + - FS 2.2 Average bit rate (Note 10) As peak bit rate FS + + - 3. Information transfer Unrestricted capability digital Others information FS + + - 3.1 (Note 2) + + - 4. Information transfer Unstructured Service data Others FS structure unit integrity + + + + - 5. Establishment of communication Demand Reserved Permanent + + + + - 6. Communication configuration Point-to-Point Multipoint Broadcast + + + + - 7. Symmetry Unidirectional Bidirectional Bidirectional symmetric asymmetric + + - Access attributes + + - 8. Access channel (and rate) FS including ATM D Note 8 and packet + + - 9. Access protocols Signalling access protocols 9.1 Layer 1 To be defined 9.2 Layer 2 I.440/I.441 to be amended for 9.3 Layer 3 I.450/I.451 broadband communication + + TABLE 1 (Contd.) + + Attributes Possible Attribute Values + + - Information access protocols 9.4 Layer 1 To be defined 9.5 Layer 2 - (Note 9) 9.6 Layer 3 - + + - General attributes + + - 10. Supplementary services As for telephony Others FS provided + + - 11. Quality of Service (Note 5) FS + + - 12. Interworking possibilities Between all video/audio services Others FS + + - 13. Operational and commercial FS + + FS - For further study TABLE 2 Service attributes and possible attribute values for broadband bearer services (Note 7) + + Attributes Possible Attribute Values + + - Information transfer attributes + + - ATM ATM 1. Information transfer mode (Circuit) Deterministic Statistical Packet Note 11 Note 11 + + - + - 2. Information transfer rate Bit rate Mbit/s Throughput Note 9 + - + - 2.1 Peak bit rate Note 8 FS + - FS 2.2 Average bit rate As peak bit rate FS (Note 10) + + - 3. Information transfer Unrestricted 7 kHz 15 kHz 7 kHz 15 kHz High Lower capability digital audio audio audio audio quality quality information (Note 6) (Note 6) stereo stereo video video (Note 6) (Note 1) (Note 1) + + - 3.1 (Note 2) Others FS + + - 4. Information transfer Unstructured Service data Others FS structure unit integrity + + + + - 5. Establishment of Demand Reserved Permanent communication + + + + - 6. Communication configuration Point-to-Point Multipoint Broadcast + + + + - 7. Symmetry Unidirectional Bidirectional Bidirectional symmetric asymmetric + + - Access attributes + + - 8. Access channel (and rate) FS including ATM D Note 8 and packet + + - 9. Access protocols Signalling access protocols 9.1 Layer 1 To be defined 9.2 Layer 2 I.440/I.441 to be amended for 9.3 Layer 3 I.450/I.451 broadband communication Information access protocols 9.4 Layer 1 To be defined 9.5 Layer 2 - 9.6 Layer 3 - Under study + + TABLE 2 (Contd.) + + Attributes Possible Attribute Values + + - High layer attributes + + - 10. Type of user information Moving pictures Sound User-to-user Others messages FS (Note 3) + - Still image Speech Text Facsimile Text/ Video- facs. tex + + - 10.1 (Note 2) + + - 11. Transport (layer 4) functions/protocol + Under study 12. Session (layer 5) functions/protocol + + - 13. Presentation (layer 6) functions/protocol (Note 4) + 13.1 Video + 13.2 Audio Under study + 13.3 Auxiliary + 13.4 User-to-user messages + + - 14. Application (layer 7) functions/protocol (Note 4) + 14.1 Video + 14.2 Audio Under study + 14.3 Auxiliary + 14.4 User-to-user messages + + - General attributes + + - 15. Supplementary services As for telephony Others FS provided + + - + - 16. Quality of Service (Note 5) Existing 7 kHz audio 15 kHz audio Others TV-quality mono/stereo mono/stereo FS + + - 17. Interworking possibilities Between all video/audio service Others FS + + - 18. Operational and commercial FS + + FS - For further study Notes to Tables 1 and 2 Note 1 - High quality video means video information with a video quality equal to or higher than that of existing TV standards (e.g., PAL, SECAM, NTSC). Lower quality video means video information with a video quality lower than that of existing TV standards (e.g., PAL, SECAM, NTSC), for videotelephony and electronic news gathering applications. Note 2 - The attribute called "structure of user information/information transfer capability" may be needed with possible attribute values multimedia, monomedium, specific structures. The inclusion of such an attribute is for further study. Note 3 - Additional user-to-user messages may be transferred from one user terminal to the other user terminal to control or to signal a special mode of operation, etc. Note 4 - Sub-attributes to the presentation and application functions/protocols dedicated to: -Video: Video end-to-end information; -Audio: Audio end-to-end information; -Auxiliary: Possible additional end-to-end information such as text, facsimile, telescript, cursor, etc.; -User-to-user messages: See Note 3. Note 5 - Quality standards to be defined taking into account existing standards of video/audio programme broadcasting services. Note 6 - This attribute value must be used in combination with other values for this attribute such as high quality video. Note 7 - In this table only attribute values of those broadband services are considered which may require higher transfer capacity than that of the H1 capacity. Attribute values of broadband services for sound retrieval and sound mail applications are not listed. Note 8 - Not to be standardized for circuit-switched bearer services. Note 9 - Throughput parameters could include average and peak bit rates possibly qualified by being fixed or variable on a call-by-call basis or during the call basis. Note 10 - Under study. Note 11 - An ATM deterministic information transfer mode is one in which the information transfer capacity of the peak bit rate is guaranteed to the user all the time. An ATM statistical information transfer mode is one in which only an average information transfer capacity is guaranteed to the user. Examples of proposed broadband services Six examples of proposed Broadband Service families follow, using attributes and attribute values and the prose description format previously presented in this appendix. 1. Broadband unrestricted bearer services 1.1 Definition These bearer services provide unrestricted end-to-end transfer of digital information without alteration between SB/TB reference points. These services require broadband channel rates. User information is transferred over an H4, H21 or H22 channel for STM(circuit) services or a virtual channel or defined capacity for ATM based services; signalling is provided over a signalling channel. 1.2 Description 1.2.1 General description For further study. 1.2.2 Specific terminology For further study. 1.2.3 Applications -contribution type audio-visual circuits; -multiple sub-rate information streams multiplexed by the user; -others for further study. 1.3 Procedures 1.3.1 Provision/Withdrawal By arrangement with the administration/RPOA. 1.3.2 Normal procedures 1.3.2.1 Activation/deactivation/registration For further study. 1.3.2.2 Invocation and operation 1.3.2.2.1 Call set-up The call is originated by: -the user selecting the required bearer service and; -indicating the address of the called user and; -if necessary, providing the desired routing requirements. Indications during the call set-up are: -after initiating a call the calling user will receive an acknowledgement that the network is able to process the call; -an indication to the called user of the arrival of the call; -when the call reaches the called user and the connection is established, an indication of this is sent to the calling user. 1.3.2.2.2 Possible procedures during the communication phase For further study. 1.3.2.2.3 Call release The call may be terminated by either or both of the users by indicating this to the network. If one user terminates the call, an appropriate indication is sent to the other user. 1.3.3 Exceptional procedures 1.3.3.1 Activation/deactivation/registration For further study. 1.3.3.2 Invocation and operation 1.3.3.2.1 Failures situations due to the calling party -user inputting an improper service request to the network will be given a failure indication; -user inputting a non-valid network address will be given a failure indication. 1.3.3.2.2 Failure situations due to called party -calling user attempting to establish a call to a user who is determined by the network to be busy, will be given a failure indication; -user attempting to establish a call to a user whose terminal equipment is unavailable will be given an appropriate failure indication; -user attempting to set up a call where the call is not accepted will, after a defined period, be given an appropriate failure indication by the network. 1.3.3.2.3 Failures situations due to the network -user attempting to set up a call but meeting problems in the network (e.g., congestion) will be given an appropriate indication. 1.3.4 Alternate procedures 1.3.4.1 Activation/deactivation/registration For further study. 1.3.4.2 Invocation and operation For further study. 1.3.5 Verification For further study. 1.3.6 Quality of Service For further study. 1.4 Network capabilities for charging For further study. 1.5 Interworking requirements For further study. 1.6 Possible supplementary services All supplementary services applicable to the switched unrestricted 64 kbit/s bearer service are applicable to broadband bearer services. Others for further study. TABLE 3 Broadband unrestricted bearer services + + Attributes/Values + + - Attributes Values + + - Information transfer attributes STM (Circuit) ATM + - 1. Information transfer mode6 Deterministic4 Statistical4 + + - + - 2. Information transfer rate H21, H22 or H4 channel bit rate (Mbit/s) + - + - 2.1 Peak bit rate (throughput) H21, H22 or H4 H21, H22 or H4 channel or other channel or other bit rate bit rate + - + + 2.2 Average bit rate as peak bit rate Under study + + - + - 3. Information transfer capability Unrestricted Unrestricted + + - + - 4. Structure Unstructured or 8 kHz integrity3 FS + + - + - 5. Establishment of communication Demand, reserved, permanent Demand, reserved, permanent + + - + - 6. Communication configuration Point-to-Point, Multipoint, Point-to- Point, Multipoint, Broadcast Broadcast + + - + - 7. Symmetry Bidirectional symmetric, Bidirectional symmetric, Bidirectional asymmetric, Bidirectional asymmetric, Unidirectional Unidirectional + + - + - Access attributes 8. Access channel and rate H21, H22 or H4 for user Virtual channel with H21, H22 or (kbit/s) information H4 channel or other bit rates 8.1 User info 8.2 Signalling/Selecting Signalling channel for signalling Signalling channel for signalling and OAM1 - under study and OAM - under study + + - + - 9. Access protocols Signalling access protocols 9.1 Layer 1 To be defined To be defined 9.2 Layer 2 I.440/I.441 need supplements for I.440/I.441 need supplements for 9.3 Layer 3 I.450/I.451 broadband communication I.450/I.451 broadband communication + + + + Attributes/Values + + - Attributes Values + + - Access attributes (Cont.) + + - Information access protocols 9.4 Layer 1 To be defined To be defined 9.5 Layer 2 - Note 2 - Note 2 9.6 Layer 3 - Note 2 - Note 2 + + - + - General attributes + + - + - 10. Supplementary services For further study For further study provided + + - + - 11. Quality of Service - End-to-end transfer delay - Delay jitter (cell jitter) - Error characteristics For further study - Information loss Under study probability + + - + - 12. Interworking possibilities For further study For further study + + - + - 13. Operational and commercial For further study. This study For further study. This study should include maintenance should include maintenance facilities. facilities. + + Notes to Table 3 Note 1 - For reserved/permanent service the operational, administrative and maintenance messages (OAM) related to this service may be conveyed over the signalling channel. Note 2 - User defined. Note 3 - Further study is needed. Note 4 - In the ATM deterministic mode a transfer capacity of the peak bit rate will be provided to the user all the time (average bit rate - peak bit rate). In the ATM statistical mode a transfer capacity of only the average gross bit rate (i.e., the average net bit rate plus cell headers) will be provided to the user (depending on the throughput class). Note 5 - Average over e.g., 100 ms. Note 6 - The values for the information transfer mode attribute need further study, for example, the distinction between the STM (circuit) and the ATM (deterministic) values needs to be investigated. 2. High quality broadband videotelephony services 2.1 Definition High quality broadband videotelephony is a symmetrical real-time bidirectional audio-visual teleservice which provides person-to-person communication for the transfer of high quality voice (sound), moving pictures, and optionally video-scanned still images between two locations. 2.2 Description 2.2.1 General description The videotelephone service is likely to be used in much the same way as the telephone service for individual communication. The enhancement being in the visibility of the communication partners which implies a number of new applications. High quality broadband videotelephony provides end-to-end communication of moving colour pictures with high spatial and temporal resolution and video quality equivalent to conventional TV standards (PAL, SECAM, NTSC) or better (component coding according to CCIR Recommendation 601), an enhanced voice/sound quality (up to 15 kHz bandwidth, possibly stereo) and optionally means for the transfer of (video-scanned) still images, graphics, text and end-to-end control messages. The videotelephone service is a teleservice, i.e., a service fully standardized in layers 1 to 7. See also Recommendation F.570. 2.2.2 Specific terminology To be added as necessary. 2.2.3 Applications Because of the high video quality this service provides, besides the means for face-to-face dialogue, the possibility of transfer of quickly moving scenes also exists. Also, three dimensional objects, graphic material, e.g., sketches, drawings, photographs, and documents containing text and graphics can be explained. Commercial and domestic scenes, instruction procedures and films can be transferred to the communication partner. Using those communication means these services may be used for the following applications: a)"face-to-face" dialogue involving at least head-and-shoulder images; b) dialogue including interactive viewing of documents such as sketches, diagrams or charts; c) audio-visual tele-education; d) health "visiting"; e) access of the user to a videoconference; f) teleshopping; g) tele-advertising; h) video-surveillance of sick persons, babies, buildings, animals etc. The examples given above are not exhaustive. Other enhanced videotelephone applications may emerge. 2.3 Procedures 2.3.1 Provision/withdrawal By arrangement with the administration/RPOA. 2.3.2 Normal procedures 2.3.2.1 Activation/deactivation/registration For further study. 2.3.2.2 Invocation and operation Visual indications, preferably alphanumeric on the screen in a selectable language concerning call set-up, progress, in-call modifications, multipoint etc. are strongly advocated. 2.3.2.2.1 Call set-up Call set-up should be available to the user as simple operation(s) with one-step or two-step invocation using addressing and, where necessary, routing information. Two possible methods are required: a) in connection with the telephony service, first a telephone connection will be set up. If the calling and the called user request video communication the appropriate broadband connection for audio- visual communication will be set up; b) by a single operation which immediately initiates the set-up of the appropriate broadband connection. Point-to-point videophone call The call set-up procedure from the user's point of view must be as simple as for telephony in order to achieve a good acceptance. Call set-up procedure from the user's point of view: Case a): Telephone service first -going off-hook; -dialling tone; -keying in the number of the called subscriber - telephone call; -initialization of video communication - videotelephone call; Case b): Videotelephone service from the very beginning -going off-hook; -dialling tone; -initialization of video communication; -keying in the number of the called subscriber - videotelephone call. Multipoint (conference) videotelephone call Within the videotelephone service conference facilities (three-party service, conference call) should be optionally provided. Appropriate network support is necessary. The procedure for operation of those conference calls is under study. 2.3.2.2.2 Possible procedures during the communication phase -It must be possible to convert between a telephone call and a videotelephone call by means of a "service change" by a simple operation by the user. Several service changes between telephony and videotelephony must be possible during a call. Note - There should not be any interruption of the audio connection recognizable for the users when changing between the telephone call and the videotelephone call. -During the videotelephone call each user has the possibility to switch over to the transmission of video-scanned pages of documents or images of objects etc., using the same camera or a special document camera. -The user can switch off his camera to prevent the sending of his picture and send a substitute image with a special comment. 2.3.2.2.3 Call release As for telephony. 2.3.3 Exceptional procedures 2.3.3.1 Activation/deactivation/registration For further study. 2.3.3.2 Invocation and operation Visual indications, preferably alphanumberic on the screen in a selectable language concerning failures or exceptional events are strongly advocated. 2.3.3.2.1 Failure situations due to the calling party For further study. 2.3.3.2.2 Failure situations due to the called party For further study. 2.3.3.2.3 Failures situations due to the network For further study. 2.3.4 Alternate procedures 2.3.4.1 Activation/deactivation/registration For further study. 2.3.4.2 Invocation and operation For further study. 2.3.5 Verification For further study. 2.3.6 Quality of Service 2.3.6.1 Audio High quality e.g., 7 kHz or 15 kHz, possibly stereo. 2.3.6.2 Picture Picture quality comparable with domestic TV receivers operating to 625- line or 525-line standards, under favourable conditions. 2.3.6.3 Delay There must be synchronism of speech and lip movement; that is to say, there should be no subjectively discernible difference in the delays of the speech and video signals. 2.4 Network capabilities for charging For further study. 2.5 Interworking requirements a) intercommunication with telephony is essential; b) intercommunication at basic level between all videotelephone services is to be assured; c) intercommunication with videoconference services, at least to the level of the basic videotelephone service is required; d) intercommunication with other audio-visual services is for further study; e) all limitations imposed by intercommunication should be signalled to terminals (other than basic telephones) participating in a call. 2.5.1 Intercommunication with telephony Considering the fact that at the beginning of the introduction of the videotelephone service the number of videotelephone subscribers compared to the number of telephone subscribers will be negligible, a fundamental requirement must be fulfilled in order to avoid that videotelephone subscribers could only communicate in a kind of a closed user group. It is essential that every videotelephone subscriber is able to reach from his videotelephone terminal every telephone subscriber. This condition must be met regardless of the technology (analogue, digital, ISDN) applied in the local exchange to which the telephone subscriber is connected. If, in case of intercommunication a videotelephone connection cannot be provided, a telephone call should be immediately initiated. If no connection results, an appropriate cause indication should be given. On the other hand, every telephone terminal must be able to reach every videotelephone terminal. (The videotelephone terminal should be preferably a multiservice terminal i.e., appropriate for videotelephone calls as well as for telephone calls.) 2.5.2 Intercommunication between different videotelephone services Basic intercommunication between videotelephone services based on different bit rates will be provided at the audiovisual qualities of the lower bit rate. 2.6 Possible supplementary services -all supplementary services applicable to telephony (including conference call); -other supplementary services, e.g., "change of service including change of connection", have to be studied. wTABLE 4 High Quality Broadband Videotelephony (Note 5) Attributes/Values + - + - Attributes Values + - + - Information transfer attributes STM(Circuit) ATM + - 1. Information tranfer mode6 Deterministic3 Statistical + - + - + - + - 2. Information transfer rate H21, H22 or H4-channel bit rate H21, H22 or H4-channel (Mbit/s) or other bit rate + - + - + - 2.1 Peak bit rate H21, H22, or H4- (throughput) channel or other bit rate + - + - + - 2.2 Average bit rate4 As peak bit rate Under study + - + - + - 3. Information transfer High quality video + 15 kHz High quality video + 15 kHz audio + User-to- capability audio + User-to-user messages user messages + - + - + - 4. Structure Unstructured Service data + - + - + - 5. Establishment of communication Demand, Reserved, Permanent Demand, Reserved, Permanent + - + - + - 6. Communication configuration Point-to-point, Multipoint Point- to-point, Multipoint + - + - + - 7. Symmetry Bidirectional symmetric Bidirectional symmetric + - + - + - Access attributes 8. Access channel and rate H2 or H4 (bit rates under study) for user information 8.1 User info Virtual channel with Virtual channel with H21, H22 or H4-channel H21, H22 or H4-channel or other bit rate or other bit rate + - + - 8.2 Signalling Signalling channel for Signalling channel under study signalling and OAM under study + - + - + - 9. Access protocols Signalling access protocols 9.1 Layer 1 To be defined To be defined 9.2 Layer 2 I.440/441 to be amended for I.440/I.441 to be amended for 9.3 Layer 3 I.450/451 broadband communica- I.450/I.451 broadband communication tion Information access protocols To be defined To be defined 9.4 Layer 1 9.5 Layer 2 Under study Under study 9.6 Layer 3 + - + W TABLE 4 (Cont.) + - + Attributes/Values + - + - Attributes Values + - + - High layer attributes Moving pictures + Sound + 10. Type of user information User-to-user messages + - + - 11. Transport (layer 4) functions/protocol + - Under study 12. Session (layer 5) functions/protocol + - + - 13. Presentation (layer 6) functions/protocol Under study. This study should include video, sound, auxiliary 13.1 Video information such as text, facsimile. 13.2 Audio etc., and User-to-user control 13.3 Auxiliary messages. 13.4 User-to-user messages + - + - 14. Application (layer 7) function/protocol 14.1 Video Under study 14.2 Audio 14.3 Auxiliary 14.4 User-to-user messages + - + - General attributes 15. Supplementary services As for telephony: others under study provided + - + - 16. Quality of service 16.1 Video Equal to or higher than existing TV - + - 16.2 Audio 15 kHz stereo (Note 1) - + - - End-to-end transfer delay - Delay jitter (call jitter) Under study Under study - Error characteristics - Information loss probability + - + - 17. Interworking possibilities With other videotelephone, telephone, and videoconference services + - + - 18. Operational and commercial For further study. This study should include maintenance facilities. + - + W Notes to Table 4 Note 1 - This value may be restricted to 7 kHz only at the electro- acoustic interface at the TE due to possible echo cancellation problems in case of handfree application. Note 2 - The broadband network is free to process the bitstream (e.g. compression, conversion to analogue etc.) as long as end-to-end service quality requirements are satisfied. Note 3 - In the ATM deterministic mode a transfer capability of the peak bit rate will be provided to the user all the time (average bit rate = peak bit rate). In the ATM statistical mode a transfer capacity of only the average gross bit rate (i.e. the average net bit rate plus cell headers) will be guaranteed to the user (depending on the throughput class). Note 4 - Average over e.g. 100 ms Note 5 - The attribute values characterize a videoconference service providing high video quality equal or higher than existing TV standards. Until now only coding mechanisms for those video qualities are available which require transfer bit rates equal or higher than the H21-channel bit rate. Due to future development in research of coding algorithms and techniques the transfer bit rates necessary for those video qualities may decrease. Note 6 - The values for the information transfer mode attribute need further study, for example, the distinction between the STM (Circuit) and the ATM (deterministic) values needs to be investigated. 3. High quality broadband videoconference services 3.1 Definition High Quality Broadband Videoconference provides person-to-person or group-to-group conferencing capability for the transfer of different high quality information types primarily including voice (sound), full motion video, moving pictures, and, optionally, video-scanned still images, documents and other video information, to support conferencing between two or more locations. 3.2 Description 3.2.1 General description High Quality Broadband Videoconference provides the necessary arrangements for real-time conferencing in which both voice and moving picture video information can be exchanged together with optional non- moving visual information, Telematic information and signalling (speaker identification, floor request, etc.) among single individuals or groups of individuals at two or more locations via the broadband ISDN. For the interconnection of terminal equipment at three or more locations, a specific interconnection facility is required, namely the Multipoint Control Unit (MCU), to which all locations are connected individually. The MCU provides proper distribution of the various signals among the connected locations and takes part in maintaining the proper procedures among the connected terminals. This videoconference service will provide the following basic management functions: Conference management functions: -call set-up, call establishment and call clearing at conference and network level; -handling of multipoint functions; -switching of proper channels to the various terminals and equipments during the call control phases of the videoconference; -chairing the meeting; -etc. Terminal management functions: -handling and management of terminal functions for audio and video; -handling and management of terminal functions for the optional transfer of non-moving visual information, Telematic information, and signalling (e.g. for speaker identification, floor request), i.e. communication functions for e.g.: - telewriting; - using a marker; - facsimile transfer; - still picture transfer; - text transfer; - conference set-up and clearing; - identification of speaker; - floor request, grant floor request signalling; - control of speaker's microphone; - line breakdown signalling; - etc. The videoconference service is a teleservice, i.e. a service fully standardized in layers 1 to 7. See also Recommendation F.560. 3.2.2 Specific terminology: To be added as necessary 3.2.3 Applications a)"Workstation" conference providing head-and-shoulder images; b) Studio-studio conferences; c) Tele-education (remote education and training); tele-lecturing; d) Tele-advertising; e) etc. The examples given above are not exhaustive. 3.3 Procedures 3.3.1 Provision/withdrawal By arrangement with the administration/RPOA. 3.3.2 Normal procedures 3.3.2.1 Activation/deactivation/registration For further study. 3.3.2.2 Invocation and operation Visual indications, preferably alphanumeric on the screen in a selectable language concerning call set-up, progress, in-call modifications, etc. are strongly advocated. Videoconferences may be provided using the following connections: -reserved or semi-permanent connections (e.g. manual set-up); -on demand connections (automatic switching); -permanent connections (leased circuits). See also Recommendation Y.112. The mode of communication should be: -two ways simultaneous (TWS) for video and audio; -two ways alternate (TWA) for all other types of information, e.g. still images, text, data, graphics. See also Recommendation Y.112. The management of a videoconference is handled by the "conference conductor". The control functions to manage the conference may be operated by the "conference conductor", by the conference operator, or by an automatic method offered through the MCU. The control functions offered to a videoconference may consist of any combination of the following: -connect participants to a conference; -re-connect a dropped videoconference participant; -contact an operator for assistance; -disconnect selected conference participants; -identify participants on the videoconference or screen participants before connection to the videoconference; -terminate the videoconference; -perform other control functions required by the supplementary facilities if used. Call operations The operations for each call may be divided in the following two phases: -call control phase: Conference call set-up, conference termination and clearing of connection. -communication phase. 3.3.2.2.1 Call set-up The network connections are established among the meeting locations either directly or through a connection between any meeting location and a MCU. The call set-up may be initiated: -on demand by the conference conductor; -on demand by the conference participants via an automatic MCU ("meet- me-conference"); -by reservation; -by installation (permanent). 1) On demand by the conference conductor a) point-to-point videoconference between studios; b) multipoint videoconference between participants at more than two locations. Call set-up should be available to the conductor as simple operation(s) with one-step or two-step invocation using addressing and, where necessary, routing information. Two possible methods should be provided: a) In connection with the telephony service, first a telephone connection will be set up. If the called user accepts video communication the appropriate broadband connection for audiovisual communication will be set up. b) By a single operation which immediately initiates the setup of the appropriate broadband connection. 2) On demand by the conference participants via an automatic MCU (meet- me-conference) Call set-up should be available to the user as simple operation(s) with one-step or two-step invocation using addressing and, where necessary, routing information, by a single operation which immediately initiates the set-up of the appropriate broadband connection. 3) By reservation (especially for international videoconferences) Due to the high bit rates used for High Quality Videoconference, a reservation may be required not only for the MCU but also at least for the international links in multipoint as well as in point-to-point conferences. Normally, the reservation of international videoconferences will be made manually. Administrations may also provide an automatic version of a reservation system for national videoconference or for the national part of international videoconferences. The process of manual reservation of international point-to-point and multipoint videoconferences needs general guidelines to ensure a harmonized operation of the international videoconference service. All reservation arrangements for international videoconference are to be made by the National Reservation Office (NRO) of the participating Administrations. Negotiations are preferably carried out by telephone, but agreed reservations must be confirmed in a written form before the call. The information needed for a reservation of a videoconference to be given by the convenor: -list of participating terminals; -starting time of the session; -closing time of the session; -symbolic name of the session; -symbolic names of the terminals. The participating Administration in an international videoconference service must agree on the following items: -minimum notice time for reservation; -maximum notice time for reservation; -minimum reservation time (duration of the session); -acceptable increments for reservation; -procedure for establishing a reservation between the NRO's a) occasional use of booking; b) regular booking; -procedure of last minute extensions; -billing procedure. (List not exhaustive, details for further study.) 4) By installation (permanent) For further study. 3.3.2.2.2 Possible procedures during the communication phase a) There may be a "Local conductor" at each meeting location. In a "conducted conference" one of the local conductors can have the additional "role" of conference conductor. b) The main task of the conference conductor is to chair the meeting in the classical sense. The "buttonpushing" for the conductor must be kept to a minimum. Opening and closing of channels (for telewriter, facsimile, etc.) is done automatically. Only the microphones and pictures of participants may be controlled by the conference conductor, but as in normal meetings this should only be performed in large or very formal meetings. If the microphones and pictures are not controlled by the conference conductor the conference is termed "non-conducted". c) The initial mode in the set-up phase and the fall back mode after change configuration is non-conducted. 3.3.2.2.3 Call release Communication termination A videoconference will be terminated by one of the following methods: 1) The conference conductor determines the conference is over and proceeds to terminate it. 2) All of the conference participants hang up. 3) The MCU disconnects the participants (e.g. when the reservation time has expired). Individual locations may disconnect without terminating the conference. Clearing of connection The network clearing of connection is a matter of signalling procedures in the ISDN and/or of administrative procedures (e.g. in case of leased lines). 3.3.3 Exceptional Procedures 3.3.3.1 Activation/deactivation/registration For further study. 3.3.3.2 Invocation and operation Visual indications, preferably alphanumeric on the screen in a selectable language concerning failures or exceptional events are strongly advocated. 3.3.3.2.1 Failures situations due to the calling party For further study. 3.3.3.2.2 Failures situations due to the called party For further study. 3.3.3.2.3 Failures situations due to the network For further study. 3.3.4 Alternate procedures 3.3.4.1 Activation/deactivation/registration For further study. 3.3.4.2 Invocation and operation For special applications, e.g. tele-education, tele-lecturing, teleadvertising, an additional type of videoconference may be applicable, too: -unidirectional videoconference with the following mode of operation: - one way communication for video; - two ways simultaneous for audio. Communication related security It is essential to have videoconference users' confidence that their videoconference will be secure. During both the call set-up phase and the communication phase, it will be the responsibility of the individual administrations to offer security mechanism based on bilateral or multilateral agreements. There are two levels of security which need to be addressed for videoconferencing: - to safeguard privacy; - to prevent unauthorized network access. Basic requirements for both levels are for further study. Others for further study. 3.3.5 Verification For further study. 3.3.6 Quality of Service 3.3.6.1 Audio High quality e.g. 7 kHz or 15 kHz, possibly stereo. 3.3.6.2 Picture Picture quality comparable with domestic TV receivers operating to 625line or 525line standards, under favourable conditions. 3.3.6.3 Delay There must be synchronism of speech and lip movements; that is to say, there should be no subjectively discernible difference in the delays of the speech and video signals. 3.4 Network capabilities for charging For further study. 3.5 Interworking requirements -Intercommunication at basic level between all videoconference services is to be assured. -Intercommunication with High Quality Broadband Videotelephony is required; with other videotelephone services should be studied. -Intercommunication with telephony is required. -Intercommunication with other audiovisual services (e.g. TV distribution services, video retrieval services) is for further study. -Intercommunication with services for still image, text, facsimile, or data communication is for further study. -All limitations imposed by intercommunication should be signalled to terminals (other than basic telephones) participating in a call. The detailed intercommunication possibilities are pointed out in Recommendations Y.112, 120, 240, 241 and 242. 3.6 Possible supplementary services Supplementary services applicable to videotelephony. Examples are: - Abbreviated Dialling; -Multi-address Calling; - Advice of Charge; - Closed User Group (CUG); -Reverse Charging. Other supplementary services, e.g. "Change of service including change of connection", have to be studied. TABLE 5 High Quality Broadband Videotelephony (Note 5) + - + Attributes/Values + - + - Attributes Values + - + - Information transfer attributes STM(Circuit) ATM + - 1. Information tranfer mode6 Deterministic3 Statistical3 + - + - + + 2. Information transfer rate2 H21, H22 or H4-channel bit rate (Mbit/s) + - + + 2.1 Peak bit rate - peak H21, H22 or H4-channel H4-channel or other (throughput) or other bit rate bit rate + - + + 2.2 Average bit rate As peak bit rate Under study + - + - + - 3. Information transfer High quality video + 15 kHz High quality video + 15 kHz audio stereo + capability audio + User-to-user messages User-to-user messages + - + - + - 4. Structure Unstructured Service data unit integrity + - + - + - 5. Establishment of communication Demand, Reserved, Permanent Demand, Reserved, Permanent + - + - + - 6. Communication configuration Multipoint/point-to-point Multipoint/point-to-point + - + - + - 7. Symmetry Bidirectional symmetric. Bidirectional symmetiric. Bidirectional Bidirectional asymmetric, others asymmetric, others for further study for further study + - + - + - Access attributes 8. Access channel and rate H2 or H4 for user information (multipoint communication) 8.1 User info Virtual channel with Virtual channel with H21, H22 or H4-channel H21, H22 or H4-channel or other bit rate or other bit rate + - + - 8.2 Signalling Signalling channel for Signalling channel under study signalling and OAM - under study + - + - + - 9. Access protocols Signalling access protocols 9.1 Layer 1 To be defined To be defined 9.2 Layer 2 I.440/441 to be amended for I.440/I.441 to be amended for 9.3 Layer 3 I.450/451 broadband communica- I.450/I.451 broadband communication tion Information access protocols To be defined To be defined 9.4 Layer 1 9.5 Layer 2 Under study Under study 9.6 Layer 3 + - + W TABLE 4 (Cont.) + - + Attributes/Values + - + - Attributes Values + - + - High layer attributes Moving pictures + Sound + 10. Type of user information User-to-User messages + - + - 11. Transport (layer 4) functions/protocol + - Under study 12. Session (layer 5) functions/protocol + - + - 13. Presentation (layer 6) functions/protocol Under study. This study should include video, sound, auxiliary 13.1 Video information such as text, facsimile. 13.2 Audio etc., and user-to-user control 13.3 Auxiliary messages. 13.4 User-to-user messages + - + - 14. Application (layer 7) function/protocol 14.1 Video Under study 14.2 Audio 14.3 Auxiliary 14.4 User-to-user messages + - + - General attributes 15. Supplementary services As for telephony: others under study provided + - + - 16. Quality of service 16.1 Video Equal to or higher than existing TV - + - 16.2 Audio 15 kHz stereo (Note 1) - + - - End-to-end transfer delay - Delay jitter (call jitter) Under study Under study - Error characteristics - Information loss probability + - + - 17. Interworking possibilities With other videoconference, videotelephone, and telephone services + - + - 18. Operational and commercial For further study. This study should include maintenance facilities. + - + W Notes to Table 5 Note 1 - This value may be restricted to 7 kHz only at the electro- acoustic interface at the TE due to possible echo cancellation problems in case of hand- free application. Note 2 - The broadband network is free to process the bit-stream (e.g. compression, conversion to analogue etc.) as long as end-to-end service quality requirements are satisfied. Note 3 - In the ATM deterministic mode a transfer capability of the peak bit rate will be provided to the user all the time (average bit rate = peak bit rate). In the ATM statistical mode a transfer capacity of only the average gross bit rate (i.e. the average net bit rate plus cell headers) will be guaranteed to the user (depending on the throughput class). Note 4 - Average over e.g. 100 ms. Note 5 - The attribute values characterize a videoconference service providing high video quality equal or higher than existing TV standards. Until now only coding mechanisms for those video qualities are available which require transfer bit rates equal or higher than the H21-channel bit rate. Due to future development in research of coding algorithms and techniques the transfer bit rates necessary for those video qualities may decrease. Note 6 - The values for the information transfer mode attribute need further study, for example, the distinction between the STM (Circuit) and the ATM (deterministic) values needs to be investigated. 4. Existing quality TV distribution services 4.1 Definition The existing quality TV distribution service provides the capability of distributing TV programmes with the quality equivalent to 525 lines NTSC or 625 lines PAL or SECAM. 4.2 Description 4.2.1 General description a) Performance This service involves the distribution of several TV programme channels to a customer's premises. Selection of the TV channel presented is controlled by the customer. It is possible for two or more different channels to be presented simultaneously, for viewing independently by a number of persons, or for recording on video tape recorders, or for selection to be made by the customer's terminal equipment. There are a number of charging mechanisms that may apply depending on the type of service selected. b) Outgoing and incoming calls In normal operation, calls are only instigated by the customer or by customer equipment (e.g. programmed video tape recorder), although he may program the network to set up calls automatically at some later time to an unattended video tape recorder at his premises. 4.2.2 Specific terminology For further study. 4.2.3 Applications For further study. 4.3 Procedures 4.3.1 Provision/withdrawal By arrangement with the administrative/RPOA. 4.3.2 Normal procedures 4.3.2.1 Activation/deactivation/registration The customer has to agree with the administration which services he wishes to be able to receive. For certain charging arrangements, there may be a need for the customer and administration to agree on a present financial limit which will not be exceeded by the accrued charges in a billing period. The service activation requires: a) the registration of the customer's identification and service profile in the list of customers held in the service administration control centre; b) allocation of logical and physical resources that will be used to provide service. At the end of the contractual time period, the administration deactivates the service: -the customer's identification is modified or deleted from the data base held at the service administration control centre; -logical and physical resources reserved for the provision of service during the activation phase are made free. 4.3.2.2 Invocation and operation Invocation may be carried out manually or by the network or by the terminal. Invocation by the network or terminal is required for connecting service to video tape recorders. Authorization may or may not be required depending on charging mechanisms and package of services. 4.3.2.2.1 Call set-up a) The customer activates his terminal equipment and indicates to the network that he wishes to make a selection of a TV channel. This request may not need to be explicit - connection may be automatically made to a particular TV service or information channel. Alternatively, the customer may select a channel from a number of channels being simultaneously presented. b) The customer selects the desired TV service. Most probably this will involve the depressing of keys on an infra-red remote controller, but other methods are possible. Selection may be of a particular channel or group of channels, or of an increase or decrease of the presently connected channel number. In some network configurations, the customer may select a channel for viewing from a large number of channels being simultaneously delivered to the home. In these circumstances, selection may be made directly by the customer's terminal equipment. c) If records held within the network indicate that the customer is authorized to receive the requested service, the network switches or otherwise connects the customer appropriately. For the case where channels are simultaneously presented, the network takes no action at this stage. d) Charging will be initiated once service is connected if charging for that service is by programme or by unit of time. e) If charging is by programme, the service will be discontinued at the end of the programme. Otherwise the service will remain connected until there is a customer request for a different service or there is an indication that service is no longer required e.g. by terminal powerdown. 4.3.2.2.2 Possible procedures during the communication phase For further study. 4.3.2.2.3 Call release The customer deactivates his terminal equipment. 4.3.3 Exceptional procedures 4.3.3.1 Activation/deactivation/registration For further study. 4.3.3.2 Invocation and operation 4.3.3.2.1 Failures situations due to the calling party If the customer is not authorized to receive the service, the network will either: i) not connect him to the service but indicate by screen text message or otherwise that he is not authorized to receive the requested service; or ii) not descramble the requested service (in cases where the customer's equipment performs the descrambling function, suitable means will be provided by the network (or otherwise) to inhibit descrambling); or iii) connect him to the service for a fixed short period of time for the purposes of encouraging the customer to subscribe to the service. This facility can only be entered into infrequently - repeated requests will result in state i) or ii). 4.3.3.2.2 Failures situations due to the called party If the customer cannot be connected to the service because of a fault condition, he may be informed of the situation by screen text message or otherwise. 4.3.3.2.3 Failures situations due to the network If the customer cannot be connected to the service because of a fault condition, he may be informed of the situation by screen text message or otherwise. 4.3.4 Alternate procedures 4.3.4.1 Activation/deactivation/registration For further study. 4.3.4.2 Invocation and operation For further study. 4.3.5 Verification For further study. 4.3.6 Quality of Service For further study. 4.4 Network capabilities for charging Charging capabilities needed for TV distribution services are different in many ways from those pertaining to telecommunication services. For further study. 4.5 Interworking requirements For further study. 4.6 Possible supplementary services For further study. 5. HDTV distribution services Note - The differences between these services and the existing quality TV distribution services are indicated in the margin. 5.1 Definition The HDTV distribution service provides the capability of distributing TV programmes with the quality of HDTV. 5.2 Description 5.2.1 General description a) Performance This service involves the distribution of HDTV programmes to a customer's premises. Selection of the TV programmes presented is controlled by the customer. It is possible for one or more different programmes to be presented simultaneously, for viewing independently by a number of persons, or for recording on video tape recorders, or for selection to be made by the customer's terminal equipment. There are a number of charging mechanisms that may apply depending on the type of service selected. b) Outgoing and incoming calls In normal operation, calls are only instigated by the customer or by customer equipment (e.g. programmed video tape recorder), although he may program the network to set-up calls automatically at some later time to an unattended video tape recorder at his premises. 5.2.2 Specific terminology For further study. 5.2.3 Applications For further study. 5.3 Procedures 5.3.1 Provision/withdrawal By arrangement with the administration/RPOA. 5.3.2 Normal procedures 5.3.2.1 Activation/deactivation/registration The customer has to agree with the administration which services he wishes to be able to receive. For certain charging arrangements, there may be a need for the customer and administration to agree on a preset financial limit which will not be exceeded by the accrued charges in a billing period. The service activation requires: a) the registration of the customer's identification and service profile in the list of customers held in the service administration control centre; b) allocation of logical and physical resources that will be used to provide service. At the end of the contractual time period, the administration deactivates the service: -the customer's identification is modified or deleted from the data base held at the service administration control centre; -logical and physical resources reserved for the provision of service during the activation phase are made free. 5.3.2.2 Invocation and operation Invocation may be carried out manually or by the network or by the terminal. Invocation by the network or terminal is required for connecting service to HDTV video tape recorders. Authorization may or may not be required depending on charging mechanisms and package of services. 5.3.2.2.1 Call set-up a) The customer activates his terminal equipment and indicates to the network that he wishes to make a selection of an HDTV programme channel. This request may not need to be explicit - connection may be automatically made to a particular HDTV service or information channel. Alternatively, the customer may select an HDTV programme channel from a number of channels being simultaneously presented. b) The customer selects the desired HDTV service. Most probably this will involve the depressing of keys on an infra-red remote controller, but other methods are possible. Selection may be of a particular channel or group of channels, or of an increase or decrease of the presently connected channel number. In some network configurations, the customer may select a channel for viewing from a number of channels being simultaneously delivered to the home. In these circumstances, selection may be made directly by the customer's terminal equipment. c) If records held within the network indicate that the customer is authorized to receive the requested service, the network switches or otherwise connects the customer appropriately. For the case where channels are simultaneously presented, the network takes no action at this stage. d) Charging will be initiated once service is connected if charging for that service is by programme or by unit of time. e) If charging is by programme, the service will be discontinued at the end of the programme. Otherwise the service will remain connected until there is a customer request for a different service or there is an indication that service is no longer required e.g. by terminal powerdown. 5.3.2.2.2 Possible procedures during the communication phase For further study. 5.3.2.2.3 Call release The customer deactivates his terminal equipment. 5.3.3 Exceptional procedures 5.3.3.1 Activation/deactivation/registration For further study. 5.3.3.2 Invocation and operation 5.3.3.2.1 Failures situations due to the calling party If the customer is not authorized to receive the service, the network will either: i) not connect him to the service but indicate by screen text message or otherwise that he is not authorized to receive the requested service; or ii) not descramble the requested service (in case where the customer's equipment performs the descrambling function, suitable means will be provided by the network (or otherwise to inhibit descrambling); or iii) connect him to the service for a fixed short period of time for the purposes of encouraging the customer to subscribe to the service. This facility can only be entered into infrequently - repeated requests will result in state i) or ii). 5.3.3.2.2 Failures situations due to the called party If the customer cannot be connected to the service because of a fault condition, he may be informed of the situation by screen text message or otherwise. 5.3.3.2.3 Failures situations due to the network If the customer cannot be connected to the service because of a fault condition, he may be informed of the situation by screen text message or otherwise. 5.3.4 Alternate procedures 5.3.4.1 Activation/deactivation/registration For further study. 5.3.4.2 Invocation and operation For further study. 5.3.5 Verification For further study. 5.3.6 Quality of service HDTV quality (under study). 5.4 Network capabilities for charging Charging capabilities needed for HDTV distribution service are different in many ways from those pertaining to telecommunication services. For further study. 5.5 Interworking requirements For further study. 5.6 Possible supplementary services For further study. w TABLE 6 + - + Attributes/Values Existing Quality TV Distribution Service* (Note 3) HDTV Distribution Service + + - + Attributes Values Values + + - + STM(Circuit) ATM STM(Circuit) ATM + - + - + - + Information transfer attributes 1. Information transfer mode6 Deterministic1 Statistical1 Deterministic1 + + - + + + - + 2. Information transfer rate H21, H22 or H4-channel bit rate H4- channel bit rate (Mbit/s) or greater - + - + - + - + 2.1 Peak bit rate H21, H22 or H4 H4-channel bit (throughput) channel or other - rate or greater bit rate - + - + - + - + 2.2 Average bit rate a peak Under study - as peak bit rate + + - + - + 3. Information transfer High quality video + 15 kHz High quality video + 15 kHz HDTV quality video + 15 kHz capability audio stereo audio stereo audio stereo + + - + - + 4. Structure Unstructured Service data unit integrity Unstructured For further study + + - + - + - + 5. Establishment of Demand, reserved Demand, reserved Demand, reserved Demand, reserved communication + + - + - + - + further study) further study) further study) further study + - + - - * Preliminary service name TABLE 6 (Cont.) + - + Attributes/Values HDTV Distribution Service + + - + Attributes Values Values + + - + Information transfer attributes (Cont.) 7. Symmetry Unidirectional Unidirectional Unidirectional Unidirectional + + - + - + Access attributes 8. Access channel and rate H2 or H4 (bit rates under Virtual channel dependent on the necessary study) for user information Virtual channel Virtual channel information transfer rate 8.1 User info with H21, H22 with H21, H22 or H4-channel or H4-channel or other bit or other bit rate rate - + - + - + 8.2 Signalling/Selecting D-Channel or a special channel D-Channel or special channel D-Channel or special channel for distribution service (under study) (under study) signalling + + - + - + - + 9. Access protocols Signalling access protocols 9.1 Layer 1 To be defined To be defined To be defined To be defined 9.2 Layer 2 I.440/441 Need supplements I.440/I.441 Need supplements I.440/441 Need supplements for broadband for broadband for broadband 9.3 Layer 3 I.450/451 communication I.450/I.451 communication I.450/451 communication Information access To be defined To be defined To be defined To be defined protocols 9.4 Layer 1 9.5 Layer 2 Under study Under study Under study Under study 9.6 Layer 3 + - + t TABLE 6 (Cont.) + - + Attributes/Values HDTV Distribution Service + + - + Attributes Values Values + + - + High layer attributes 10. Type of user information Moving picture + sound + data Moving picture + sound + data Moving picture + sound + data + + - + - + 11. Transfer (layer 4) functions/protocol For further study For further study For further study + + - + - + 12. Session (layer 5) function/protocol For further study For further study For further study + + - + - + 13. Presentation (layer 6) function/protocol 13.1 Video For further study, awaiting For further study, awaiting For further study, awaiting 13.2 Audio suitable coding schemes suitable coding schemes suitable coding schemes 13.3 Auxiliary 13.4 User-to-user messages Not applicable Not applicable Not applicable + + - + - + 14. Application (layer 7) function/protocol 14.1 Video 14.2 Audio For further study For further study For further study 14.3 Auxiliary 14.4 User-to-user messages Not applicable Not applicable Not applicable + + - + - + General attributes 15. Supplementary services For further study For further study For further study provided Not applicable Not applicable + - + TABLE 6 (Cont.) + - + Attributes/Values HDTV Distribution Service + + - + Attributes Values Values + + - + General attributes (Cont.) 16. Quality of service 16.1 Video Equal to existing TV Equal to existing TV HDTV quality (or better) + - + - + 16.2 Audio Equal to existing HiFi stereo Equal to existing HiFi stereo Equal to existing HiFi stereo standards (or better) standards (or better) standards (or better) + - + - + - End-to-end transfer delay - Delay jitter-cell jitter - Error characteristics Under study Under study Under study Under study - Information loss probability + + - + - + - + 17. Interworking possibilities For further study For further study For further study For further study + + - + - + - + 18. Operational and commercial For further study For further study For further study For further study + - + - Not applicable W W Notes to Table 6 Note 1 - In the ATM deterministic mode, a transfer capacity of the peak bit rate will be provided to the user all the time (average bit rate = peak bit rate). In the ATM statistical mode a transfer capacity of only the average gross bit rate (i.e. the average net bit rate plus cell headers) will be provided to the user (depending on the throughput class). Note 2 - Average over e.g. 100 ms. Note 3 - The attribute values characterize a TV distribution service providing high video quality equal or higher than existing TV standards. Until now only coding mechanisms for those video qualities are available which require transfer bit rates equal or higher than the H21-channel bit rate. Due to future development in research of coding algorithms and techniques, the transfer bit rates necessary for those video qualities may decrease. Note 6 - The values for the information transfer mode attribute need further study. For example, the distinction between the STM (Circuit) and the ATM (deterministic) values needs to be investigated. 6. Broadband Videotex services 6.1 Definition A Broadband Videotex service is an interactive service which provides, through appropriate access by standardized procedures, for users of Broadband Videotex terminals to communicate with data bases via telecommunications networks. 6.2 Description 6.2.1 General description The Broadband Videotex service includes the following set of characteristics: 1) information is generally in an alphanumeric and/or pictorial form; 2) information is stored in a data base; 3) information is transmitted between the data base and users by telecommunications networks; 4) displayable information is presented on a suitably modified television receiver or other visual display device; 5) access is under the user's direct or indirect control; 6) the service is easily operated by the general public as well as specialist users, i.e. the service is user-friendly; 7) the service provides facilities for users to create and modify information in the data bases; 8) the service provides data base management facilities which allow information providers to create, maintain and manage data bases and to manage closed user group facilities. Broadband Videotex may offer the following advantages over narrow-band Videotex: 1) higher spatial resolution; 2) greater colour capabilities; 3) faster speed of picture composition; 4) improved audio capabilities; 5) higher quality animation; 6) higher quality moving pictures. 6.2.2 Specific terminology See CCITT Red Book Recommendation F.300 Section 2 - "Definition of terms". 6.2.3 Applications With utilization of the above advantages, the following possible applications may be significantly enhanced when supported by Broadband Videotex: -remote education and training; -telesoftware; -teleshopping; -news retrieval. Other applications may also benefit from the advantages of Broadband Videotex. The detailed definition of these applications is not part of this service specification. 6.3 Procedures 6.3.1 Provision/withdrawal By arrangement with the administration/RPOA. 6.3.2 Normal procedures 6.3.2.1 Activation/deactivation/registration Activation and registration require the provision of the customer's identification and Broadband Videotex profile. 6.3.2.2 Invocation and operation The service is invoked by normal call procedures. 6.3.2.2.1 Call set-up The call is originated by: -the user selecting the required Broadband Videotex service; and -if necessary, providing the desired routing requirements. After initiating a call, the calling user will receive an acknowledgement that the network is able to process the call. When the call reaches the Broadband Videotex service centre and the connection is established, a page is sent to the user. 6.3.2.2.2 Possible procedures during the communication phase See CCITT Red Book Recommendation F.300 Section 3 "Functionalities of the service". 6.3.2.2.3 Call release The call is released by the calling party indicating this to the network. 6.3.3 Exceptional procedures 6.3.3.1 Activation/deactivation/registration For further study. 6.3.3.2 Invocation and operation 6.3.3.2.1 Failures situations due to the calling party A user inputting an improper service request to the network will be given a failure indication. 6.3.3.2.2 Failures situations due to the called party A user making a valid access to an unavailable service/application will be given an appropriate failure indication. 6.3.3.2.3 Failures situations due to the network A user attempting to set-up a call but meeting problems in the network (e.g. congestion), will be given an appropriate indication. 6.3.4 Alternate procedures 6.3.4.1 Activation/deactivation/registration For further study. 6.3.4.2 Invocation and operation For further study. 6.3.5 Verification For further study. 6.3.6 Quality of Service The identification of Quality of Service parameters and the quantification of associated values is for further study. Network performance parameters are outside the scope of the service specification. 6.4 Network capabilities for charging For further study. 6.5 Interworking requirements 6.5.1 Interworking with other Telematic services See CCITT Red Book Recommendation F.300 Section 6. 6.5.2 Interworking with other Broadband services For further study. 6.6 Possible supplementary services For further study. Appendix 4 (to Part II/Annex) Examples of high layer functions of audio-visual services, e.g. Videoconference Recoup Appendix 5 Framework for the study of important ATM Service Parameters Reocup Recoup w Appendix 6 (to Part II/Annex) Bit rates for moving pictures (Mbit/s) + + Service quality Uncompressed Compressed Brief description of quality bit rate bit rate classes (Note 5) (Note 1) (Note 2) Mbit/s Mbit/s + - + + + Quality A About 1000 92 - > 200 High definition television (HDTV) Quality B 216 30/46-145 Digital component-coded (Note 3) signal 145 - Digitally-coded NTSC, PAL, (Note 5) SECAM Quality C - 20 - 45 Digitally-coded NTSC, PAL, (Note 4) SECAM for distribution Quality D - 6 - 34 Reduced quality video services including television Quality E - 0.384 - 1.92 Reduced spatial resolution and movement-portrayal Quality F - 0.064 Highly-reduced spatial resolution and movement- portrayal + + Note 1 - The bit rates given under this column are meant to be generated by the signal source (e.g. within a studio). They are not intended to be used for the transport of signals, either for contribution or for distribution. Note 2 - Derived from the source signals ("uncompressed bit rate") the bit rates in this column may be used for the transport of video signals through the networks. In this connection it should be recognized that CMTT makes a distinction between two types of signals: -for "contribution", where the signal may be subject to post- production studio processing; -for "distribution", where the signal will not be subject to such processing. Generally, a higher degree of compression can be applied for distribution than for contribution signals. A typical application of a contribution signal is the transfer of video signals between studios (sometimes via long international connections). An example of the use of distribution signals is for the transfer of video signals to domestic premises. Note 3 - 30 Mbit/s will probably be suitable for distribution. The CMTT at this time thinks that it may not be sufficient for contribution and, for the latter, a minimum of 45 Mbit/s may be required. Note 4 - Some administrations believe that it may, at some time in the future, be possible to reduce the rate to 8 Mbit/s, or even 6 Mbit/s, but further study on this possibility is required. Note 5 - Compression may be necessary to accommodate the signal within an H4-channel. High-definition television (QA) The CCIR is attempting to recommend a studio production standard. It seems to be likely that the spatial resolution will be about double that corresponding to CCIR Recommendation 601 and the aspect ratio may be 5/3 instead of 4/3. Digital component-coded signal (QB) Two coding methods could be applied for this service quality: -component coding based on the studio standard, as defined in CCIR Recommendation 601. This is the preferred method; -uncompressed coding of composite video signals. Although component coding will produce a superior quality, both coding methods are considered to fall under service quality B. Digitally-coded NTSC, PAL, SECAM for distribution (QC) The sampling standard for component signals is derived from CCIR Recommendation 601. By applying source coding techniques with reduction factors, the resulting picture quality corresponds to today's analogue encoding systems (PAL, SECAM, NTSC). The same category includes digital signals derived directly by coding the composite PAL, SECAM, NTSC signal. Reduced definition (QD) This picture quality retains high temporal resolutions with reduced spatial resolution. An example of this application is action-oriented news-gathering. Reduced resolution (QE) The specification of this quality as a standard for videotelephony with restricted picture quality is under study. The reduced resolution could be achieved by considerable reduction in the spatial luminance and chrominance resolution and in movement-portrayal. Highly-reduced resolution (QF) It is not at present possible to indicate the degree and type of picture impairment that will be considered as acceptable, because this depends on the application. Concerning the costs of codecs, it should be pointed out that the cost optimization should cover all the elements involved in a connection and, in particular, the most cost-sensitive element is the subscriber loop. A high bit rate will decrease the cost of codecs but might increase that of transmission and of switching. For a given picture quality, the use of a unique coding standard for interactive and distribution services has the merit of compatible processing standards in the terminals. For different picture qualities, the use of different coding schemes (preferably compatible) could allow a more efficient use of transmission capacity of the network and simple relationships between different quality levels. Appendix 7 (to Part II/Annex) Sources required by different customer categories The following points should be noted: a) The table gives a list of a number of simultaneous services. In the case of TV-quality and videotelephony/videoconference services, no particular channel bit rate is inferred. b) The table when completed will give the number of services used simultaneously by the customer. This does not imply that the TV and stereo sound services need necessarily be switched by the network. In a star-shaped network with individual customer accesses and a centralized selection of TV programmes, privacy aspects must be taken into account. Note - As in existing TV networks, distribution of a cluster of TV and sound programmes to the customers' premises with selection taking place in the in- house installation has certain advantages and should therefore also be considered. c) The equivalent ISDN primary rate access services for residential customers are intended for a number of high bit rate services such as: -high-speed telefax; -high-speed data transmission for the interconnection of personal computers; -document transfer; -broadband Videotex. w These services are particularly important for the provision of business services including the home environment. d) The provision of a stereo sound capability in the direction from the user to the network for a residential customer is for a music-mail service. e) The residential customer should have equivalent ISDN basic access services. f) It is suggested that two TV-quality services are required by the business customer in the network-to-user direction, one for normal TV reception and another one for video retrieval. One is needed in the user-to-network direction for all customer categories. g) Does the business customer require HiFi stereo sound for employee entertainment and the commercial equivalent of music-mail? h) The business customer will use the equivalent primary access services for similar applications to those required by residential customers, but will more capacity be needed? i) The number of equivalent basic access services should reflect the increased usage by business and the increased numbers of users (employees). j) Signalling and control of these services are not dealt with in this table. + + Residential Residential Small or Customer Customer Medium Customer Business Categories Customer Services (Notes 1, 2, 4, 5) + - + + - Network User to3 Network User to3 to User Network to User Network direction direction direction direction + - + + + + - TV-quality 3 - 4 - 2 - services + - + + + + - Videotelephony/ 1 1 1 - 2 1 - 2 Videoconference + - + + + + - Equivalent ISDN primary access - - 1 - 2 1 - 2 services + - + + + + - HiFi stereo sound 4 - 4 - + - + + + + - Equivalent ISDN basic access 1 - 2 1 - 2 1 - 2 1 - 2 services + + Note 1 - Differentiation based on statistical material. Small: less than 5 employees per workplace. Medium: between 5 and 20 employees per workplace. Note 2 - Large business (more than 20 employees per workplace) may require multiple accesses. Note 3 - If videotelephone/videoconference services are operated at a TV-quality level, the same channel can also be utilized for other TV- quality services. Note 4 - Small businesses may be operated in a home environment. Note 5 - Two accesses may be required for security reasons. PART III - NETWORK ASPECTS Contents 1. Architecture models 2. ATM characteristics 3. Broadband channel rates 4. User-network interface (UNI) 5. Network characteristics * * * 1. Architecture models 1.1 Functional architecture The general architecture of the ISDN from the functional point of view is described in Recommendation I.324. Although Recommendation I.324 focuses on the 64 kbit/s based ISDN, the general functional concepts apply also to the BISDN. However, specific detailed concepts may not apply and require study. Figure 1.1 shows the basic architectural model of ISDN, including the broadband aspects. The figure is a modified version of Figure 1 of Recommendation I.324; the broadband capability is shown explicitly and the 64 kbit/s is not partitioned into categories such as circuitswitched, packetswitched, etc. The figure shows the main information transfer and signalling functional capabilities : -local functional capabilities (LFC), i.e., local exchange functions and possibly including remote switching, crossconnects, muldexes, etc.; -interexchange signalling functional capabilities; -64 kbit/s based functional capabilities; -broadband functional capabilities. These components need not be provided by distinct networks, but may be combined as appropriate for a particular implementation. 1.2 Reference and physical configurations for usernetwork access 1.2.1Reference configuration The reference configuration defined in Figure 1/I.411 and shown here as Figure 1.2 is considered sufficiently general to be applicable not only for a basic access and a primary rate access, but also to a broadband access. Both reference points S and T are valid for broadband accesses. FIGURE 1.2 BISDN reference configuration The functions of the NT1 are, in principle, identical for 64 kbit/s based ISDN and BISDN. The same applies to the NT2. 1.2.2 Physical configurations In order to clearly illustrate the broadband aspects, the notations for reference points and for functional groupings with broadband capabilities are appended with the letter B (e.g., BNT1, TB). Interfaces at reference points SB and TB will be standardized. These interfaces will support all ISDN services, not just broadband services. Figures 1.3 and 1.4 give examples of physical configurations illustrating combinations of physical interfaces at various reference points. The examples cover configurations that could possibly be supported by standardized interfaces and reference points SB and TB. Other configurations may also be supported. A direct connection of terminals to the NT1 cannot be excluded for the time being taking particularly into account the residential subscribers. Configurations j) and k) of Figure 1.3 and configuration g) of Figure 1.4 show such direct connections and require that the interface specifications for SB and TB have a high degree of commonality. Such commonality is highly desirable. The feasibility of achieving the needed commonality requires further study. One objective in designing interfaces is to support multiple terminals simultaneously via a simplified BNT2 (e.g., a BNT2 consisting solely of physical connections). For broadband services the inhouse communication is expected to be important and this should be possible without activating the entire network. FIGURE 1.3 Examples of physical configurations for broadband customer environment Note - The notations for functional groupings and for reference points not appended with the letter B are related to 64 kbit/s based ISDN services. FIGURE 1.4 Examples of physical configurations for broadband customer environment, explicitly providing for multiple terminals Note 1 - The interface S may or may not exist and may either be star or bus structured. Note 2 - The structure of the SB and TB interfaces requires further study. Note 3 - The BNT functions may be limited to Layer 1 functions like multiplexing and demultiplexing of bit streams and contention resolution. Note 4 - The necessity to define this type of configuration requires further study. Note 5 - The notations for functional groupings and for reference points not appended with the letter B are related to 64 kbit/s based ISDN services. FIGURE 1.4 (continued) Examples of physical configurations for broadband customer environment, explicitly providing for multiple terminals 1.3 BISDN protocol model for ATM The BISDN protocol model for ATM is shown in Figure 1.5. Two specific layers related to the ATM functions are: -an ATM layer that is common to all services and provides cell transfer capabilities; and -an adaptation layer that is service dependent. FIGURE 1.5 BISDN protocol model for ATM 1.3.1 ATM layer The boundary between the ATM layer and the adaptation layer corresponds to the boundary between functions devoted to the header and functions devoted to the information field. 1.3.2 Adaptation layer The adaptation layer supports higher layer functions of the user and control planes and supports connections between ATM and nonATM interfaces. Information is mapped by the adaptation layer into ATM cells. At the transmitting end, information units (e.g., LAP D frames) are segmented or information units (e.g., PCM voice samples) are collected to be inserted into ATM cells. At the receiving end, the information units are reassembled (e.g., Lap D frames) or readout (e.g., PCM voice samples) from ATM cells. Any adaptation layer specific information (e.g., data field length, time stamps, sequence number) that must be passed between peer adaptation layers is contained in the information field of the ATM cell. The adaptation layer could be terminated in a Network Termination (NT), Network Adapter (NA), Terminal Adapter (TA), Terminal Equipment (TE) and Exchange Termination (ET) (see Figure 1.6). The Network Adapter function includes those adaptation functions that are necessary between ATM and nonATM parts of ISDN. FIGURE 1.6 Scope of adaptation layer Note - ( Indicates adaptation layer protocol termination point. 1.3.3 Adaptation layer functions Examples of adaptation functions include Continuous Bit Stream Oriented (CBO) services adaptation functions, packet mode services adaptation functions and connectionless services adaptation functions. -CBO adaptation functions: Continuous Bit Stream Oriented (CBO) services are those which involve an uninterrupted flow of digital information, for example, 64 kbit/s PCM voice. The CBO adaptation functions support these services over an ATM network. Functions that may be performed within the adaptation layer include: 1.cell assembly and disassembly; 2.compensation for the variable delay of the ATM network; 3.handling of lost cell conditions; 4.clock recovery; some alternatives are to synchronize the output bit stream to the network clock or to the source bit stream; 5.mapping of control signals (e.g., V.35) into the ATM cell stream. -Existing packet mode services adaptation functions: Existing packet mode services (e.g., LAP D) can be supported by the CBO adaptation functions. This does not take advantage of the idle periods between data transmission. The packet mode adaptation layer provides bandwidth savings by taking advantage of the bursty nature of packet services. Operations that may be carried out by the packet mode adaptation functions include: 1.detection of information blocks from the higher layer; 2.dividing information blocks into ATM cells; 3.handling of partially filled cells; 4.reassembling information blocks from received ATM cells; 5.sending information blocks to the higher layer; 6.rate adaption; 7.action on loss of cells. -Adaptation function may be defined for connectionless services. 2. ATM characteristics 2.1 Basis for selecting ATM for the BISDN 2.1.1Key functional/technical orientations for the asynchronous transfer mode The transfer mode in the target BISDN will be ATM. Conceptually this transfer mode is something intermediate between circuit and packet modes. It offers a similar functional transparency to the information flow as in a circuit technique. However, because the bandwidth consumption throughout the network is instantaneously adapted to the strict need, it has the flow characteristics of a packet mode. The main features are: -information is packetized in a way well suited to real time information transfer; -all services, narrowband and broadband, will be supported; this transfer mode is service independent. The need for a service dependent adaptation layer is confirmed. This assumes a major difference from the wellknown packet switching technique in that neither error detection and correction of the user information nor elaborate flow control procedures can be achieved at the basic transfer layer of the network. 2.1.2 Advantages/disadvantages A. Advantages i) Service flexibility: -decoupling of user services from network capabilities; -any combination of synchronous and asynchronous traffic is allowed (from a low bit rate to the maximum bit rate usable); -dynamic allocation of bandwidth on a demand basis facilitates the use of independent user clocks; -asymmetric flows are easily accommodated; -foreseeable service evolutions can be accommodated easily. The service requirements (coding schemes, etc.) may be subject to important variations within the lifetime of the network to be defined. ii) Network flexibility: -in the long term all services may be supported by only one transfer mode (i.e. with a unique transfer protocol), a unique physical layer and a unique control structure. This integrated network is expected to be more cost effective than separate networks; -interworking can be easily accommodated since the packet nature of the transfer mode provides inherent rate adaption and synchronization; -ATM allows network resources to be flexibly shared among simultaneous communications; -ATM allows network efficiency to be enhanced through statistical multiplexing. This may be particularly advantageous in the trunk network. B. Disadvantages Compared to current circuit switching techniques, ATM requires increased overhead in the form of packet headers. This implies the need for processing on the part of the network to recognize and process these headers. Further investigation is required to see what complexity (packet creation, bandwidth allocation) is implied in terminal and network equipments that would implement such a transfer capability. It also implies that the full capacity of a physical channel on which this technique is applied cannot be utilized, but must be reduced to take into account the capacity needed for overhead. This may not be a significant factor in the application of this technique to broadband applications. There may be further reductions in capacity, e.g., if the information field of the cell is only partially filled in order to control the packetization delay. 2.2 Support of CBO services ATM may be designed so that it can support CBO services and offer a grade of service comparable to that of STM, because ATM can: a) provide sequence integrity (for virtual channels using the same physical path); b) provide an internal transfer delay comparable or shorter than STM, taking into account that: -the switch transfer delay is likely to be smaller than the fixed delay introduced by an STD switch; -to support CBO services endtoend, the cell jitter can be removed, which introduces an additional transfer delay comparable to the jitter; -the endtoend total absolute delay can meet anticipated grade of service limits, through adequate cell size definition. c)fulfill the overall delay requirements during the evolution phase when interworking with circuitoriented networks. 2.3 Status of ATM definition 2.3.1 General characteristics 2.3.1.1 Outofband signalling - cell sequence integrity Two characteristics of the ATM mentioned in I.121 are slightly different. As a connectionoriented technique, ATM uses what is commonly referred to as "outofband" signalling; a communication consists of dissociated call control and information transfer phases. ATM is also basically a virtual channel technique. In that sense, the ATM network preserves cell sequence integrity - which means that the cells do not arrive out of sequence from access reference point to access reference point (e.g., S/T, interworking). Dynamically altering the priority on a virtual channel, if this function is allowed, could lead to a temporary loss of cell sequence integrity. ATM may also be able to preserve the sequence of cells belonging to different virtual channels, when those channels connect the same two interfaces. This concept is related to the issue of whether the cell header function of routing is implemented implicitly or explicitly (see header functions). As signalling is outofband, the handling of a call needs at least two virtual channels, one for the user information and one for the signalling. The number of signalling virtual channels on an interface is possibly more than one, and depends on the network architecture. 2.3.1.2 Transmission media for ATM ATM is also considered as a technique which can be operated on any transmission medium. Although this is felt to be obvious, it has not been made clear whether or not that has an impact on the ATM definition and on the sharing of functions between the physical medium dependent layer and the ATM layer. 2.3.2 The ATM cell - functions and structure 2.3.2.1 Basic agreed issues The basic and fundamental agreements are expressed in I.121: all cells have the same format at a given reference point and the information field size is the same throughout the ATM network. 2.3.2.2Header functions and size Uniformity of header size at all reference points It may be desirable to have the header size remain the same at all reference points, and two issues need to be clarified: -although it is considered as highly desirable to have the maximum commonality between S and T reference points, the lack of detailed material addressing NT functions and requirements in a broadband environment suggests keeping such a principle only as a target for the time being; -there is not an agreement on all of the functions supported by the header; needs might be different at different reference points inside the network. Proposed header functions Agreement on the functions supported by the header appears as a major decision that has a strong impact on all other issues related to the cell structure. Three functions have been identified as mandatory: virtual channel identification, error detection on the header and indication of unassigned cells. The task of the VCI is the identification of a connection at a reference point. The VCI has no endtoend significance. The last function relates to cells that have not been allocated to any virtual channel transferring information (i.e. user, signalling, network management ...); a tendency is to consider that unassigned cells should be identified through a specific virtual channel number. Header functions: two options There are at present two major views concerning the need for additional functions supported by the header: -the first option considers that basically, the header only contains a virtual channel number and the related error control field, at any reference point. That option does not preclude some other header supported functions, insofar as they can be implicitly supported by the virtual channel number; -the second option proposes explicit fields supporting additional functions; in that case, the header internal structure could be different, without precluding having the same header size, at different reference points. The first option has the advantage of allowing the shortest possible header. The second option is presented as a way of simplifying routing equipment inside the network (i.e. crossconnects) or in the local plant (i.e. remote electronics). Classification of the proposed header functions Table 2.1 lists functions that have been proposed in contributions, classified in four classes: -class 1A: mandatory functions, mandatory explicit fields -class 1B: mandatory functions that can be supported by the virtual channel number -class 2: additional functions that can be supported by the virtual channel number -class 3: other additional functions which cannot be supported by the virtual channel number. A virtual path function has been proposed to form a bundle of virtual circuits and route this bundle as a single unit through a labelled crossconnect. The Virtual Path Identifier (VPI) in the header can be a separate field or, as has been suggested, can be a part of the Virtual Channel Identification (VCI). When multiple physical links are used for the transmission of a single ATM flow between two nodes, cell sequence numbering has been suggested as a way to preserve cell sequence integrity. Payload type identifies cells using a given virtual channel for additional information (e.g. NOH, test, etc.). Evaluation of the field sizes for the proposed header functions A first rough evaluation of the minimum and maximum field sizes required by each function, in case supporting it by an explicit field inside the header has been made. Results are in Table 2.1. It is, however, recognized that, in option 2 (see header functions: two options), all functions are not required at all reference points. Different header internal formats would in this case coexist at different reference points. Comments: -The header functions as contained in this table are not necessarily exhaustive. -The influence of synchronization on the header is for further study. -It has been proposed that some additional capacity should be foreseen in the header to allow for future contingencies. TABLE 2.1 Proposal for header field sizes required by each function Note 1 - If that function is agreed as requiring an explicit field, it needs N bits. Note 2 - Additional capacity is needed in the VCI if this function is implicitly supported by the VCI. Note 3 - To add to what error detection already needs. Note 4 - It is for further study whether "Payload Type" belongs to class 2 or class 3. Bit error ratio and cell loss ratio The quality provided by the ATM layer is obviously related specifically to the cell loss ratio. Queueing and bit errors cause cell losses. It has been highlighted that increasing the header size has the effect of increasing the error probability inside the header and therefore the cell loss ratio. Models and assumptions have to be taken as a basis for studying the implication of all these issues. Transmission medium utilization efficiency The transmission medium utilization efficiency is not considered as a major determining factor, insofar as the headertoinformation field ratio is not too high (in the range of about 10%). However, Table 1 shows that the information field size cannot be decided independently of the choice between options 1 and 2 (see header functions: two options). Header size The size of the header should be chosen in the range of 3 to 8 bytes. To determine the appropriate size, urgent study is required on header functions and on the capacity for future and additional use. In addition, the relationship between the header size and the information field size needs to be considered. 2.3.2.3 Information field The size of the information field should be chosen in the range of 32 to 120 bytes. Two items need clarification for determining the information field size: - endtoend Quality of Service - voice In case of voice, two major issues have been mentioned due to the necessity of including cell assembly/disassembly delay in the overall delay: -when interworking with 2wire lines, the round trip delay has to be kept within boundaries to minimize the use of echo cancellation; where these limits are is not clear at present and should preferably be established by acceptance tests. At least for economical reasons, the alternative of using echo cancellers on a large scale is not agreed. Another possibility is to use partially filled cells for voice. If voice is a significant part of the traffic, this would create an important decrease in transmission efficiency; -the one way delay has also to be considered. Some studies assess that long distance and international calls are considered to offer insufficient quality by some users. Whether that is only caused by echo, by echo processing or by other reasons is not clear. It is however assumed that out of acceptance tests some maximum value for the delay would result, applying to endtoend 4wire connections. That maximum acceptable delay should then be shared between all parts of the network, that includes cell assembling delay at the emitting side, transmission delay, switching delay, cell jitter absorption at the receiving side, and possible signal processing at both sides as well. The result is that careful studies of all delay related items are urgently needed because certain solutions may eliminate some introduction scenarios. Endtoend Quality of Service - cell loss handling Other points have been mentioned, relating to endtoend cell loss recovering protocols. For some services (e.g., voice), cell losses might be acceptable. However, the amount of lost information (= information field size), has to remain within limits. The limits guaranteeing a given Quality of Service have to be studied. For other services, where cell loss is more critical, protocols performed at the adaptation layer could reconstruct the lost information in case of a detected cell loss. Such protocols exist; it has however been mentioned that they could become quickly very complex, possibly unachievable, when the information field size increases. A side effect of such protocols is the introduction of additional delays at the emitting and receiving sides, when the signal is organized and combined with forward redundancy. The following examples have been mentioned: HiFi sound and compressed digital video. 2.3.2.4 Optimum header sizetoinformation field size ratio Assuming a given header size, studies on the network traffic behaviour tend to highlight that an optimum information field size exists. Optimized items are cell jitter and buffer sizes in the network and at the receiving side. This optimum is not obvious and results are very sensitive to the information throughput rate. 2.4 Conclusion Due to a strong relationship between all the previous items, the dependencies need to be clearly identified. Figure 2.1 shows a possible way of structuring the decisions and therefore suggests priorities in the studies. 3. Broadband channel rates In this section channels refer to virtual channels with appropriate physical channel bit rates. Taking into account the various services that can be supported by B- ISDN, the channel bit rate should be defined in relation to the coding of video-signals, and to data transmission as the transfer of these signals will represent a major application. In addition to B, Ho and H1-channels, B-ISDN will support broadband channels H2 and H4 having the following bit rates: 1) H21 broadband channel: The bit rate of this broadband channel will be 32768 kbit/s; 2) H22 broadband channel: The bit rate of this broadband channel will be: -in the approximate range of 43 to 45 Mbit/s; -an integer multiple of 64 kbit/s; -not greater than the payload of existing third level asynchronous transmission systems of the 1.5 Mbit/s based hierarchy. Consistent with these three requirements, one objective is to maximize the bit rate of the H22 broadband channel. Specific rates of: H22 = 43200 Mbit/s and 43776 Mbit/s are integer multiples of 9 x 64 kbit/s and have been proposed for ease of interworking with the synchronous digital hierarchy. Studies will continue with the aim to define a H2 channel bit rate in the range between H21 and H22 for international interconnections. 3) H4 broadband channel: The bit rate of this broadband channel will be: -in the range of 132 to 138240 Mbit/s; -an integer multiple of 64 kbit/s. When subsequently defining the exact bit rate, the following factors will be taken into account: -the ATM basis of the 150 Mbit/s user-network interface; -the possible need, during an interim period, to use STM techniques to carry the bit stream of this channel in transmission systems based on the existing and the new digital hierarchy; -the possible need to support a television signal multiplex as specified by the CMTT. Specific rates of: H4 = 134784 Mbit/s and 135360 Mbit/s are integer multiples of 9 x 64 kbit/s and have been proposed for ease of interworking with the synchronous digital hierarchy. A specific rate of: H4 = 135168 Mbit/s, an integer multiple of 2048 kbit/s, has also been proposed and has received considerable support. The final specification of H22 and H4 broadband channel rates should be such that: 4 H21 rate _ H4 rate 3 H22 rate _ H4 rate Additional broadband channels may be defined if necessary. 4. User-network interface (UNI) 4.1 General This section defines some structural, physical and functional characteristics of broadband user-network interfaces. The characteristics discussed apply to interfaces at the T8 and at the S8 reference points. The commonality between the interface of T8 and at S8 reference points is a matter of further study. B-ISDN user-network interfaces will be standardized at two bit rates. One of these will be at approximately 150 Mbit/s and the other will be at approximately 600 Mbit/s. The broadband UNI need not be symmetrical. Each of these interfaces must be capable of supporting broadband services as well as 64 kbit/s based ISDN services. As an objective, the target solution for both B-ISDN user-network interfaces is based on ATM. The following technical guidelines have been taken into account in specifying these interfaces: i) only digital signals should be carried across the user-network interface (all sound and video signals digitized); ii) a frame repetition rate of 8 kHz may be convenient at the S/T reference point to allocate conventional 8-kHz-structured information channels (e.g., B) and to allocate all future broadband channels having a bit rate which in any case should be a multiple of 8 kbit/s; iii) the total information transfer rate of the interface structures at the reference points S/T does not need to be restricted by the existing transmission hierarchies in the network; iv) the interface should allow the transfer of the existing 64 kbit/s based ISDN services and the support of DSS-1 (Digital Subscriber Line Signalling System Number 1). The following general guidelines should be used when further defining these interfaces: i) a unique interface at the T reference point should be aimed at, including both the interactive and the distributive services; ii) the linking between interactive and distributive services should be carefully studied; iii) the possibility of offering simultaneously a certain number of non- switched TV programmes to all the subscribers should be investigated; iv) this interface at the T reference point should be flexible to accommodate various subscriber requirements and service evolutions. Other interface capabilities such as maintenance are not considered in this section. 4.2 User-network interface structure 4.2.1 Structure of 150 Mbit/s UNI The structure of 150 Mbit/s UNI will be unique and will be based on one of the following alternatives: 1) ATM: This structure shown in case a) and case b) of Figure 4.1 uses only labelled multiplexing with cell interleaving. This category (ATM) has two possible alternatives: a) no frame structure is imposed on this interface; b) all cells are aligned in a frame structure constructed by periodically located synchronization cells; 2) ATM within a non-ATM frame: This structure shown in case c) of Figure 4.1 places ATM cells in the payload of a frame constructed by using overhead not based on ATM cells. Note - In the evolution to B-ISDN, a frame structure similar to Figure 4.2(e) may also be considered as one alternative. 4.2.2 Structure of 600 Mbit/s UNI Five candidate structures as shown in Figure 4.2 have been identified for the 600 Mbit/s UNI. Structures shown in cases a), b) and c) of Figure 4.2 are identical to cases a), b) and c) of Figure 4.1. Structures shown in cases d) and c) of Figure 4.2 have the payload partitioned into payload modules, where case e) shows some of these in STM for possible use in an interim period. The 600 Mbit/s UNI may be constructed as if derived by (bit, byte, cell) interleaving of four 150 Mbit/s structures, and in this case, the gross bit rate of the 600 Mbit/s UNI will be four times the gross bit rate of the 150 Mbit/s UNI. The structure of the 600 Mbit/s interface may need to provide for the capability of supporting services whose rates exceed the rate of the H4 broadband channel. This item requires further study. 4.3 Physical and functional characteristics 4.3.1 Physical characteristics Layer 1 of the broadband UNI requires electrical or optical transmission capable of supporting the requisite rate. As an objective, the interfaces should allow for the support of point- to-multipoint configurations. 4.3.2 Functional characteristics The channel mix need not be the same in both directions of transmission. 4.3.3 Timing characteristics The NT1 will derive bit timing information from the aggregate bit stream received from the network. In case a) of Figure 4.1 and of Figure 4.2, no frame timing is provided. Only cell delineation is provided using randomly located synchronization cells. In case b) of Figure 4.1 and of Figure 4.2, frame timing is provided using periodically located synchronization cells. In the cases c) of Figure 4.1 and c), d) and e) shown in Figure 4.2, frame timing is provided from the overhead information. The ATM stream within the payload or a payload module may be self delineated i.e., cells are delineated by inserting synchronization cells randomly in unassigned cells or periodically. Alternatively, cell delineation can be achieved by using the periodic structure of the payload. In all cases the exact method for cell delineation is for further study. Cell delineation by using the periodic structure of the payload has the advantage of more efficient use of the payload. The drawback is the need for the transmission layer to provide this periodic structure at every point where cell delimiting is to be performed. The alternative is to use a self-delineated ATM flow. Advantages mentioned are independence between the cell delimiting process and the transmission sub-layer (desirable at NT), simplicity and security of the mechanism. A combined method has been mentioned when applying ATM to the payload of transmission systems (Figure 4.3). The role of the transmission adapter is to process synchronizing cells a) and to reinsert them b). The need for synchronization in the ATM network requires further study. 5. Network characteristics 5.1 Relationship of interfaces UNI will be defined according to the user needs. Maximum commonality between UNI and the network node interfaces is aimed at, but should not place undue burden in the UNI nor compromise the service needs of the UNI. 5.2 Transmission of ATM ATM can be supported by any digital transmission hierarchy or system (e.g., existing hierarchies G.702, the new synchronous hierarchy G.707, G.708, G.709 and any future hierarchy that may be defined). That means that ATM might be used at any standardized interface (e.g., inside the payload or possibly the gross bit rate at any level of the plesiochronous hierarchies). It has been suggested that ATM could be applied inside narrow-band digital channels (e.g., end-to-end) for some applications. The transfer of information by means of a stream of cells is the basic concept of ATM. It is desirable to be able to perform this process at the highest practical bit rate. Standardization of a broadband digital transmission hierarchy has to accommodate these principles. The information payload capacity of a broadband user-network interface must support a varying mix of broadband and narrow-band services. It was agreed that ATM has the flexibility to meet this requirement. Key parameters for mapping ATM into UNI structure are: -header size; -cell size; -payload capacity; -total simultaneous service rate; -frame synchronization method. Selection of all the above parameters are inter-related. Two approaches have been discussed. One approach uses ATM cells in the payload of a synchronous frame. The other uses ATM cells over the entire interface. These approaches have been defined in detail in section 4.2 for the UNI. They may also be applicable to the NNI. The second could use an ATM based transmission hierarchy. The assessment that such a hierarchy would be more complex than a synchronous hierarchy and therefore not achievable at similar bit rates is not agreed. The feasibility of an ATM transmission hierarchy is therefore mentioned as an issue to be addressed when defining the broadband transmission hierarchy. The UNI and NNI must be able to carry a service for the transport of user information at the H4 rate using the ATM structure including ATM overhead. For the UNI, capacity must also be allocated for signalling and narrow-band services. A synchronous frame and synchronous overhead is not necessary for ATM but may be used at least for interim solutions. The selection of the preferred 5.3 ATM layer and transmission layer The boundary between the ATM layer and the transmission dependent layer has not yet been completely clarified. Referring to header functions, some of the functions that were not agreed could be considered as medium dependent. For example, the Medium Access Control (MAC) function for a shared medium customer arrangement could be considered to be within or beneath the ATM layer. As another example, bit error monitoring, although provided by the ATM layer, could also have to be provided by the transmission layer, depending on the characteristics of the transmission medium. 5.4 Synchronization The synchronization characteristics described in section 4.3.3 for the UNI may also be applicable for the NNI. 5.5 Signalling considerations In B-ISDN, signalling and user information are carried on separate ATM virtual channels. A user may have multiple signalling entities connected to the network connection control management via separate ATM virtual channels. Enhanced or extended I.441 and I.451 access protocols will be used in B-ISDN to accommodate additional B-ISDN capabilities. 5.6 Traffic management and usage monitoring 5.6.1 Source characterization Two types of service sources have been classified according to the traffic patterns they produce: -constant traffic sources, Constant traffic sources produce a fixed rate of information, e.g., PCM encoded speech; -variable traffic sources, Variable traffic sources produce a variable rate of information, e.g., bursty data sources. 5.6.2 Source indication at call establishment The signalling messages sent by a user to establish a call may include the following types of information: -source traffic characteristics e.g., burstiness; -required network transport capabilities e.g., Quality of Service parameters. 5.6.3 Network resource management at call establishment In response to the source indication the network may manage resources in several ways; such as: -dedicate resources to a given connection; -share resources among multiple connections; -share resources among a class of connections (e.g., connections supporting bursty data sources). For each of the above-mentioned alternatives, networks may manage resources according to the following examples: Case A In this case sufficient resources are provided to accommodate the expected maximum source bit rate. It could be used for continuous bit stream oriented services as well as other services. Case B In this case resources are provided at a level somewhere between the expected peak and average source bit rate. This strategy could be applied to bursty sources. Others ways of managing resources may also be envisaged. 5.6.4 Usage monitoring The ATM layer does not provide flow control in the classical sense. There is a need to implement functions that safeguard the network against malfunctions, wrong implementations, fraud, sabotage, etc. An example is given to indicate a possible way to control and protect the network. Three parameters are suggested as examples to characterize a specific service: -peak value: defined as a maximum number of cells per time unit, measured in a relatively short time period; -maximum average value: defined as a maximum number of cells per time unit, measured in a relatively long time period; -peak duration: defined as the maximum time at peak level (used to characterize the source burstiness). In order to monitor these values, it is necessary to consider the delay jitter introduced by ATM network. In case of violation, the network can drop cells. In order to avoid cell losses, the terminal may have to implement an algorithm that complements the control functions of the network. The control procedures and definition of mechanisms for monitoring the parameters are for further study. For the time being it has been concluded: In ATM a user could attempt to send traffic exceeding the characteristic negotiated at call establishment. ATM networks will provide usage monitoring to detect such situations. When the negotiated capacity is being exceeded, appropriate action is taken by the network to protect the Quality of Service provided to other network users. Further study is needed. 5.6.5 Flow control For further study. 5.6.6 Congestion handling For further study. 6. Adaptation between ATM and non-ATM parts of the ISDN Adaptation is envisaged between ATM based and 64 kbit/s based networks and terminals. For that purpose, network adaptations and terminal adaptations will be defined. Figure 6.1 illustrates different terminals to be connected to the different parts of the network: Case 1 illustrates a non-ATM terminal (e.g., for basic access is connected to a non-ATM part of a network). Case 2 illustrates a non-ATM terminal connected through a terminal adaptor to the B-ISDN part of the network. In this case, the terminal adaptor allows individual calls to be handled by the ATM part of the network. Case 3 illustrates the case where the entire signal from a non-ATM terminal (e.g., entire 2B + I signal of basic access) transported transparently through the ATM part of the network and terminated on the non-ATM part of the network. Case 4 illustrates an ATM terminal connected to the B-ISDN part of the network. FIGURE 6.1 Adaptation between ATM and non-ATM parts of ISDN NA: Network adaptor, adopting ATM functions to non-ATM functions and vice versa. Note - NT functions are not shown explicitly in this figure. Connections identified by letters a), b), c), d) will be defined at a later stage. These different access configurations present six adaptation cases. Some of the connections should be described in more detail. Problems of signalling are not shown. PART IV - ITEMS FOR FURTHER STUDY 1. General The items to be studied in the next study period can be divided according to the following scheme: -ISDN architecture; -services; -transfer mode; -user-network interface; -impact of customer premises' networks on B-ISDN; -interworking aspects; -intra-network aspects; -performance requirements; -network evolution scenario; -operation and maintenance aspects. In the following paragraphs, only the key words are given without possible arguments. A number of items are strongly related and should be studied in combination. The structuring of the study points does not reflect the necessary organization of the work but they can be grouped together into the following categories: -services; -user-network interfaces; -networking techniques; -network modelling; -operation and maintenance aspects; -interworking. In order to perform the work during the next study period it is necessary to reach an early agreement over some basic issues like e.g., ATM parameters, combined with channel rates and the bit rate at the UNI. 2. Study items 2.1 ISDN architecture -overall architectural mode including broadband aspects: -intelligent network architecture; -O & M capabilities; -enhanced services, -extensions for new capabilities, -procedures for deriving network requirements from the architectural model, -LAN interconnection through the ISDN, -virtual network principles, -architecture for interactive services and distribution services. 2.2 Services -definition of broadband: -bearer services ) connectionless and -teleservices ) connection-oriented, -service aspects of user-network interfaces: -simultaneous services; -multi-facility requirements for a given service, -application and improvement of methodology for description of services, -parameters for services e.g.: -information transfer rate; -quality classes; -network and terminal aspects; -traffic parameters; -source characteristics. -technical procedures for service operation, -the relation between services and coding, specifically videocoding/display aspects, -intercommunication requirements: -between broadband services; -between broadband services and existing ISDN services, -listing of possible applications of broadband services. 2.3 Transfer mode -physical layer: -transmission implications; -timing requirements/characteristics; -error characteristic requirements, -ATM layer: -cell parameters: cell size information field size header functionality and size -cell delimiting, -Adaptation layer: -synchronization techniques; -signalling requirements; -support of continuous bit stream-oriented services; -STM and ATM signal mapping. 2.4 User-network interfaces 2.4.1 General aspects -types of UNIs, -commonality of UNI and NNI, -compatibility with existing interfaces, -impact on evolution process, -maintenance and management functions, -signalling, -commonality of interfaces at S and T reference points. 2.4.2 Layer 1 characteristics -interface structure, -gross bit rates, -functional characteristics, -transmission characteristics, -physical configuration. 2.4.3 Aspects above layer 1 -signalling requirements, -service-specific functions, -commonality between signalling in B-ISDN and 64 kbit/s based ISDN. 2.4.4 Network aspects -terminal portability, -functionality of NTs, -topology, -access control, -different configurations of UNIs. 2.5 Impact of customer premises' networks (CPN) on B-ISDN -intra-premises communication, -user requirements, -functional division between CPN (including private ISDNs) and public ISDN, -signalling requirements, -standardization of interfaces, -adapter units, -relation to home electronic systems, -relation to LAN models. 2.6 Interworking aspects -interworking schemes with non-ISDN networks, -evolution strategies, -location and function of interworking units, -numbering, routing and charging implications, -inter-network interfaces. 2.7 Operational and maintenance aspects -integrity and security, -maintenance entities, -charging aspects, -network flexibility, -network dimensioning, -overall network performance aspects, -network management: -traffic management; -police functions; -congestion control; -call-related resource allocation. 2.8 Intra-network aspects -transmission implications, -numbering, -routing, -integration with existing networks, -call control, -adaptation between B-ISDN and 64 kbit/s based ISDN, -synchronization. 2.9 Performance requirements 2.10 Network evolution scenario