============================================================ Question 1/XV - Characteristics of equipment for the digital transmission of sound programme signals (Continuation of Question 2/XV 1985-88) Considering (1) that conversion may be required between the two coding standards given in Recommendation J.41; (2) that conversion may be required between the coding standards given in Recommendations J.41 and J.43; (3) that synchronization problems associated with the digital transmission of sound-programme signals in the international plesiochronous network may have been identified; (4) that CMTT are continuing their studies on coding methods for sound- programme channels at rates above and below 384 kbit/s, 1. What modifications are required in existing Recommendations J.41, J.42, J.43 and J.44? 2. What new Recommendations are required for digital sound programme transmission? Points for study 1. Conversion between the two coding standards given in Recommendation J.41. 2.Conversion between the coding standards given in Recommendations J.41 and J.43. 3.Characteristics of equipment for the coding of analogue sound signals at bit rates other than 384 kbit/s. 4. Harmonization of CCITT Recommendations with those of CMTT. Notes 1. CMTT is responsible for recommending standards for the digital encoding of sound-programme signals and account should be taken of their work in this area. 2. Study Group XVIII are responsible for general network issues and should be kept informed of any likely network implications arising from the study of this Question, including coding standards originating in CMTT. ============================================================ Question 2/XV - Characteristics of equipment for the digital transmission of television signals (Continuation of Question 3/XV 1985-88) Considering (1) that CMTT is studying coding standards to be used in the transmission of broadcast-type television signals over the digital network; (2) that it is becoming increasingly difficult to carry television signals over standardized digital paths; (3) that CMTT Recommendations 604 and 658 refer to Digital Television Transmission and Mixed Analogue and Digital Transmission of Analogue Composite Television Signals, respectively; (4) that CMTT Report 646 describes the CMTT's studies on digital and mixed analogue-and-ditital transmission of television signals, 1. What should be the characteristics of equipment for the digital transmission of television signals over the digital network? 2. What should be the characteristics of transmission equipment for the digital transmission of television signals over standardized digital paths in a mixed analogue and digital network? Points for study 1.Characteristics of video interfaces. 2. Characteristics of digital transmission interfaces. 3. Test methods. 4. Maintenance aspects. 5.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 6.Characteristics of the equipment when signals are presented in a variety of forms - including: 6.1 analogue composite signals 6.2 multiplexed analogue component signals 6.3 digital component signals 6.4 encrypted analogue signals 6.5 encrypted digital signals 6.6 high definition television (HDTV) signals 7.Characteristics when the equipment is used for: 7.1 contribution 7.2 primary distribution 7.3secondary distribution taking into account potential needs for harmonization with non-distributive services, see Question 3/XV (Visual telephone systems). Notes 1. CMTT is responsible for recommending standards for the digital encoding of television signals of broadcast type and testing methods for television transmission, and account should be taken of their work in this area. 2. Study Group IV is responsible for the maintenance of television transmission links, and account should be taken of its work in this area. 3. Account should be taken of the studies of broadband ISDN undertaken by Study Group XVIII. 4. The study of this Question should be coordinated with the study of Question 3/XV (Visual telephone systems). 5. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 6. Study Group XVIII are responsible for general network issues and should be kept informed of any likely network implications arising from the study of this Question including coding standards originating in CMTT. ============================================================ Question 3/XV - Visual telephone systems including videoconferencing and videophone (Continuation of Question 4/XV 1985-88) Considering (1) that Recommendation H.100 provides a generic definition of services involving the transmission of visual information and associated speech (monophonic/stereophonic) on networks used for telephony and other telecommunications applications; (2) that such services include videoconferencing and videophone as defined in H.200/AV100-Series Recommendations (see Annexes 1 and 2); (3) that a number of videoconferencing systems are already in operation and interworking of these is required; (4) that a number of administrations are examining the introduction of a videophone service through ISDN and that experiments and trials of such services are in progress in a number of countries; (5) that the scale of the demand has not yet been established; (6) that differing facilities may be required by different classes of subscriber but these have not yet been clearly identified and defined; (7) that the problems of international working will be easier to resolve if they are studied while national plans are still in a preliminary and formative stage; (8) that since digital transmission is economical and suitable for long- distance visual communications it will, therefore, be used for long- distance transmission in the visual telephone service; moreover, narrow- band ISDN and future broadband ISDN will also be used for providing the visual telephone service; (9) that N times 64 kbit/s bit rates are requested for videoconferencing and videophone services, and that such services could be provided on a switched mode basis if synchronization from end to end is available; (10) that in addition to videoconferencing and videophone it is expected that other various services (e.g. video lecturing, video transmission, surveillance and video information retrieval) will be required and that intercommunication between audiovisual terminals for those services is essential; (11) that, for videoconferencing, a reservation system for booking calls is required to ensure connection at the time of actual usage; (12) that both moving and still picture systems are necessary, 1. for the moving picture system: 1.1 What system architecture should be recommended, particularly respecting the use of different modes applying one or two B channels of the ISDN-basic access? 1.2 What system parameters and transmission standards should be recommended? 1.3 What should be recommended for equipment characteristics? 1.4 What characteristics should be recommended for the subscriber terminals and their environments? 1.5 What should be recommended for multipoint visual telephony? 1.6 What Recommendations should be made concerning picture quality and assessment, particularly respecting the use of different modes applying one or two B channels of the ISDN-basic access? 1.7 What Recommendations should be made specifically for videoconferencing? 1.8 What revision of the existing H.100-Series Recommendations is necessary? 2. What system parameters should be recommended for the transmission of still pictures or sequences of still pictures? Points for study 1.System architecture for moving picture system: 1.1Structure of system using ISDN or other networks for different services. 1.2Hypothetical reference connections and circuits. 1.3National extensions. 1.4User interfaces with network. 1.5Synchronization and timing aspects. 1.6Requirements for signalling and switching. 1.7Definitions of setup and disconnect procedures for N x 64 kbit/s channels. 2.System parameters and transmission standards for the moving picture system: 2.1Performance objectives for the HRCs. 2.2Bit rates to be used on the connection. 2.3 Frame structure for different bit rates. 2.4Communication procedures and channels for system control signals. 2.5Characteristics of interface with the local network and with subscriber terminals. 2.6Methods for the separate and combined transmission of sound and picture. 2.7Characteristics of audio channels. 3.Specifications for equipment in the moving picture system: 3.1Specification of world-wide video coding algorithm(s), parameters and equipment in various bit rates such as n x 384 kbit/s and m x 64 kbit/s for narrowband ISDN. 3.2Video coding algorithm, parameters and equipment for Asynchronous Transfer Mode (ATM) in broadband ISDN, in particular: 3.2.1use of static bandwidth flexibility offered by ATM, 3.2.2variable bit rate video coding techniques, 3.2.3influence of cell loss on image quality, 3.2.4coder/decoder synchronization in presence of cell delay jitter, 3.2.5harmonization of distributive and communicative video services. 3.3Transmission equipment especially designed for visual telephony such as remultiplexers, television standards convertors, transcoders, etc. 4.Characteristics for subscriber terminals and their environments in the moving picture system: 4.1Terminal functions desired for various services. 4.2Requirements for the lighting and acoustic environment where terminal equipments are placed. 4.3Interfaces between users and terminals, e.g. for video, speech (monophonic/stereophonic) data, etc. 4.4Functional specifications for interworking - particularly Control and Indication (C&I) signals. 5.Specification of multipoint videoconferencing and videophone systems using standardized video codecs, particularly for: 5.1System architecture. 5.2Communication control protocol. 5.3 Picture processing method. 5.4Speech processing method, taking into account speech quality impairments due to embedded echo suppression schemes in coders. 5.5Data signal handling. 6.Quality aspects for the moving picture system: 6.1Methods of subjective testing including the development of test tapes containing standardized sequences of moving pictures with different degrees of motion. 6.2Evaluation of pictures containing distortion in both spatial and temporal domains. 6.3Effects of large signal delay. 6.4Quality aspects of the tandem connection of codecs. 6.5Quality of Service for the applications concerned. 7. Videoconferencing specifications for the moving picture system: 7.1Specifications of control and data signals for the split screen system and their transmission method. 7.2Specification of communication reservation system - particularly on: 7.2.1necessary information, 7.2.2parameter definition and values, 7.2.3service capabilities, 7.2.4protocol for international working. Notes 1.The study of this Question should be coordinated with: 1.1 Study Group I for services definition, 1.2 Study Group II for network operation issues, 1.3 Study Group XVIII for ISDN issues. 2.A moving picture system always includes associated speech. 3. The study of this Question should be coordinated with the study of Question 21/XV. ANNEX 1 (to Question 3/XV) Outline draft Recommendation H.200/AV.262 codec for audiovisual services at m x 64 kbit/s 1. Scope 2. Brief specification 3. Source coder 3.1 Source format a) Full CIF: 288 lines x 360 pels x 29.97 Hz1 b) Format smaller than full CIF: 1/4 CIF, 144 lines x 180 pels x 29.97 Hz* Note - The possibility of a third format of 4/9(2/3x2/3) CIF is under study. Interconnection between different formats is on the basis of format b). 3.2 Video source coding algorithm 3.3 Data rate control 3.4 Forced updating 4. Video multiplex coder 4.1 Data structure 4.2 Video multiplex arrangement 4.3 Multipoint considerations 5. Video data buffering 6. Transmission coder 6.1 Bit rate 6.2 Video clock justification 6.3 Frame structure as per Recommendation H.221. 6.4 Audio coding 6.5 Data transmission 6.6 Error handling 6.7 Encryption 6.8 Network interface ANNEX 2 (to Question 3/XV) Outline draft Recommendation H.200/AV.320: Videophone systems and terminal equipment Proposed contents 1. Scope 2. Definitions 3. System description Block diagram and identification of elements Signals Use of infrastructure, options of bit rate etc. Call control arrangements Optional enhancements 4. Terminal requirements Audio Video C&I Optional enhancements (including additional C&I) 5. Intercommunications Appendix 1: Study and discussion points 1. Scope This Recommendation covers the technical requirements for videophone services. As a minimum, two videophone services are standardized: narrow-band videophone, and broadband videophone; the possibility of standardizing more than one narrow-band videophone service is not precluded for the time being. (See Appendix 1, Note 1.) The service requirements for videophone services are presented in Recommendation Y.120; video and audio coding systems, and other technical set aspects common to audiovisual services are covered in other Recommendations in the H.200-Series. 2. Definitions (To be completed.) 3. System description 3.1 Block diagram and identification elements Videophone instrument; camera; monitor; microphone; loudspeaker; handset; control unit; audio codec; video codec; transmission multiplex; network termination; interfaces (...); optional enchancements (low speed data port, document camera, facsimile ...); broadband/narrow-band gateway. (NB: for interworking arrangements, see section 5.) 3.2 Signals Videophone signals are classified as video, audio, data 1, and data 2, as follows: -Audio signals are continuous traffic and require real-time transmission (Note 2). -Video signals are also continuous traffic; the bit rate allocated to video signals should be as high as possible, in order to maximize the quality within the available capacity. -Data 1 signals include still pictures, facsimile, and documents, or other facilities requiring bit rates comparable with those for audio or video; this signal occurs only occasionally as required, and may temporarily displace all or part of the audiovisual signal content; it should be noted that data 1 signals are associated only with optional enhancements to the basic videophone system; therefore the opening of a path to carry such signals is preceded by negotiation between the terminals. -Data 2 signals include telewriting/marker, and some system control signals by definition, the path provided for these signals is permanent and at a fairly low bit rate (for example 2400 bits per second). 3.3 Infrastructure and bit rate options The following types of channel configurations for videophone service are being considered: Type A ("Vp 54"): one B-channel (e.g. 16 kbit/s audio and about 46.4 kbit/s video). Type B ("Vp 128" (Note)): two B-channels (e.g. 64 kbit/s audio-plus, 64 kbit/s video), or (e.g. 16 kbit/s audio plus about 109.6 kbit/s video). Type BB ("Vp-BB"): a broadband system (high quality audio and high bit rate video). (Separate Recommendations AV.321, AV.322 ... will be formed for those systems finally selected for standardization.) Note - It is desired to standardize only one configuration for type B from the engineering point of view. This matter is, however, subject to market/service requirements. There must be provision for basic interworking of audiovisual facilities between all such systems standardized, albeit at the qualities applicable to the lower bit rate (Note 3). 3.4 Videophone Vp 64 Use of AV.221 frame structure; use of video coding system H.12y (proposed assignment for video coding Recommendation at 45-128 kbit/s); use of audio coding to possible draft Recommendation (16 kbit/s); identified subset of C&I from Recommendation AV.230 (audiovisual system control and indications). 3.5 Videophone Vp 128 Here are two examples listed. Choice of one of these or other configurations is for further study. 1) Example of 16 kbit/s audio Synchronization of two B-channels (use of H.221 frame structure in both channels); audio coding to possible draft Recommendation; video coding to H.12y (proposed assignment for video coding at 45-110 kbit/s); C&I to Recommendation AV.230. 2) Example of 64 kbit/s audio-plus Use of frame structure AV.221; audio coding to Recommendation G.722 (48- 64 kbit/s ADPCM 7 kHz); video coding to H.12y; C&I to Recommendation AV.230. 3.6 Broadband videophone Frame structure; audio coding to Recommendation G.722; video coding to H.12(m) - (refers to high bit-rate video coding for local networks); C&I Recommendation AV.230. 3.7 Call control arrangements Establishment of audio call prior to establishment of second channel if applicable. 3.8 Optional enhancements (To be completed.) 4. Terminal requirements 4.1 Audio Microphones and sound system; loudspeakers; echo; audio alignment. 4.2 Video Cameras; monitors; lighting; video alignment. 4.3 Control and indications (C&I) C&I are chosen from the general audiovisual set contained in Recommendation AV.230. Very few C&Is are needed for the basic viodeophone service. AIA - indicate audio active: not-AIA shows that the source has been muted; AIA does not indicate whether anyone is actually speaking. VIA - indicates video active: not-VIA is important, indicating that the video source has deliberately been suppressed - there is no transmission fault involved. VRA - ready to activate video; required if mutual readiness of terminals to transmit/receive video is necessary prior to setting up a suitable signal path or activating the exhange on an existing path. 4.4 Optional enhancements Equipment requirements (to be completed). Control and indications: appropriate C&I to be selected from Y.230. 5. Interworking The mechanisms for interworking with other services are described in this section. References made to general mechanisms as set out in Recommendations AV.240, AV.241 ... . 5.1 Interworking between different videophone terminal types Videophones Vp 64 and Vp 128 Videophones Vp 64 and Vp-BB Videophones Vp 128 and Vp-BB 5.2 Interworking with telephony Interworking with ISDN telephones Interworking with PSTN telephones 5.3 Interworking with videoconferencing Videophones Vp 64/Vp 128 and videoconference VC 384 Videophone Vp-BB and videoconference VC 384 Videophones Vp 64/Vp 128 and videoconference VC-BB Videophone Vp-BB and videoconference VC-BB 5.4 Interworking with audiographic teleconferencing 5.5 Interworking with video surveillance Appendix 1 Note 1 - It is anticipated that this Recommendation will be split into a number of Recommendations AV.321, 322 ... each of which would cover a single videophone service (narrow-band, broadband ...). However large parts of these Recommendations would have identical wording, while in the points of divergence the actual choices between alternatives have not yet been made; for the time being therefore it is convenient to treat all the text in a single document. Note 2 - In order to reduce the average bit rate of audio signals, voice activation can be introduced (in which case the audio signals are no longer continuous). Note 3 - Such provision must be in the network, if it is not possible in the terminals. ============================================================ Question 4/XV - Harmonization of audiovisual systems (New Question) Considering (1) that audiovisual services are to be offered in which different combinations of facilities (speech, pictures, Telematics, etc.) may be used during a connection; (2) that such services include videoconferencing, audiographic and Telematic teleconferencing and videophone as studied in other Questions; (3) that other related services may be defined in the future for special applications; (4) that such services should be offered for the simultaneous interconnection of two, three or more terminals in different locations as necessary; (5) that frequently interconnection may be between terminals which are not identical in the facilities which they have available and that in general intending callers will not be aware of the capabilities of the distant terminal; (6) that, in the case of three or more terminals, one or more multipoint control units (MCU) will be required within the network to distribute appropriately the signals representing the various facilities; (7) that, under some circumstances, connections will be required between terminals on networks operating at different bit rates; in particular, services such as videophone and videoconferencing may be offered both on broadband and narrow-band networks requiring gateways between these for interconnection; (8) that in addition to the facilities perceived by the user other signals will be required for the proper organization and control of the system, especially in a multipoint environment; (9) that Recommendation H.200 sets out a framework for Recommendations covering the defined services and the necessary technical conditions for implementing them in a harmonized and interworkable way (see Annexes 1 to 5), 1. What basic signal structure should be recommended for utilization on interconnections of various bit rates corresponding to the bearer services defined in Recommendation....? 2. What modifications should be made to Recommendation H.221, in particular to take into account synchronization aspects when several independent B channels are used? 3. How should recommended coding methods for audio and still or moving television images and Telematic facilities be incorporated into the basic signal structures such that optimal interworking conditions are secured? 4. What equipments and procedures should be recommended to establish correct interworking between similar and dissimilar terminals taking into account the facilities available at each? 5. What harmonized set of control and indication should be recommended to be available within the technical implementation to facilitate correct operation and provide information required by user-friendly terminals? 6. What should be recommended for the specification of multipoint control units for the various types of interconnection and for the procedures required for establishing multipoint calls on digital networks? 7. What should be recommended for the specification that should be applied to equipment required at gateways between different networks and/or interconnection bit rates? Notes 1.The study of this Question should be coordinated with: 1.1 Study Group I for service definition, 1.2 Study Group II for network operation issue, 1.3 Study Group VIII for Telematic issues, 1.4 Study Group XVIII for ISDN issues. 2. The study of this Question should be coordinated with the study of Question 21/XV. ANNEX 1 (to Question 4/XV) Enhanced draft Recommendation H.200 FRAMEWORK FOR RECOMMENDATIONS FOR AUDIOVISUAL SERVICES I. Service definition CCITT Rec. No. AV.100 General Recommendation for AV services F.700 AV.110 Teleconference services F.700, F.710 AV.111 Audiographic conference service AV.112 Videoconference service AV.120 Videophone services AV.121 Basic narrow-band videophone service in the ISDN F... AV.130 ... (Other AV Services) II. Infrastructure AV.200 General Recommendation for AV service infrastructure AV.210 Reference network configuration AV.220 General Recommendation for frame structures AV.221 Frame structure for a 64 kbit/s channel in audiovisual teleservices H.221 AV.222 Frame structure for 384 - 2048 kbit/s channels audiovisual teleservices H.222 AV.223 ... (Frame structures for higher bit-rates) AV.230 General Recommendation for AV system control and indications AV.231 Multipoint control unit for 64 kbit/s AV AV.232 Multipoint control for 384 - 2048 kbit/s AV.233 AV.240 Principles for communication between AV terminals AV.241 System aspects for the use of the 7 kHz audio codec within 64 kbit/s G.72Y AV.242 System for establishing communication between AV terminals using one or two 64 kbit/s channels AV.250 Audio coding AV.251 Narrow-band audio coding at 64 kbit/s G.711 AV.252 Wideband audio coding in 64 kbit/s G.722 AV.253 Audio coding at 40/32 kbit/s (using G.721/728 or extending G.722 down) AV.254 Narrow-band speech coding at 16 kbit/s AV.260 Video coding AV.261 AV.262 n x 384 kbit/s video codec H.261 AV.263 m x 64 kbit/s video codec H.12xy III. Systems and terminal equipment AV.300 General Recommendations for AV systems and terminals AV.310 (Requirements for teleconferencing) AV.311 Audiographic system and terminal requirements AV.312 Videoconference system and terminal requirements AV.313 Teleconference protocol AV.320 Requirements for videophone services IV. Network aspects AV.400 AV.410 Reservation systems AV.420 MLC for use in audiovisual calls AV.430 Call control C&I AV.440 Multipoint call set-up Note 1 - It is intended to merge the substance of existing Recommendations H.100, 110 into this framework in the next study period. Note 2 - Entries in parentheses are indicative of the purpose of the various positions in the framework. Appendix (to Recommendation H.200) Present status and contents of proposed Recommendations in H.200 I. Service definitions AV.100 General Recommendation for audiovisual services (SG I, MM, 1988) List of specific services included in the general set. List of facilities (or "media") included in the general set. Call-control requirements, including multipoint. Interworking between various AV services. AV.110 Teleconference services (SG I, MM, 1988) Draft Recommendation F.700 (COM I-R 23 Part III.7) AV.111 Audiographic conference service (SG I/II, MM, 1992) Description of service; basic facilities. Optional facilities. Terminal configuration and accommodation. Control and indications. Perceived performance on international calls. Network accesses applicable to the service. Availability and conditions of international service. Supplementary services (cass forwarding/transfer, interconnection to other types of audiovisual service terminal). Use of Telematic facilities. Quality description for audio, taking into account transducer and room performance, options as to the particular coding used from the infrastructure set, and the effect of transmission errors. AV.112 Videoconference service (SG I/II, MM, 1989) As for AV.111 above with the following additions: Video system (see also AV.100, AV.110 and AV.313). Terminal configuration and accommodation includes video aspects. Quality description for video including effect of terminal transducers and room conditions, video coding options from the infrastructure set, and the effect of transmission errors (the description must take into account the fact that video coding may be changed within the network, for example from high bit rate to low bit rate coding). AV.120 Videophone service (SG I/II, MM, 1992) As for the videoconference service AV.112 above, though of course the details will differ in many respects, see also AV.320. AV.121 Basic narrow-band videophone service in the ISDN (SG I, MM, 1988) Draft Recommendation F... (COM I-R 22 Part IV.3). AV.130 Other audiovisual services Such Recommendations should cover audiovisual services not already covered by teleconferencing or videophone. Known applications are telemedicine and remote lecturing. II. Infrastructure Recommendations AV.200General Recommendation for audiovisual service infrastructure (SG XV, NDK, 1992) Outline proposed in COM XV-R 26 (Annex 1 to Part B.5). AV.210 Reference network configuration of AV services (SG XV, NDK, 1992) Description/explanation. Definitions. Reference configuration. Interfaces. Functional specification for multipoint working (refer to AV.230). Interconnections between "broadband" and lower bit rate networks. Interregional interconnections. AV.220 General Recommendations for frame structure (SG XV, NDK, 1992) Short umbrella Recommendation for the AV.220 series AV.221Frame structure for 64 kbit/s channel in audiovisual teleservices (SG XV, NDK, 1988) Draft Recommendation H.221 (COM XV-R 26 Part C.7, April 1988) AV.222Frame structures for 384 - 2048 kbit/s channels in AV teleservices (SG XV, NDK, 1988) Utilization of Recommendation H.221 with additional 64 kbit/s channels for video, etc. Utilization of frame structures for 1544 and 2048 kbit/s to Recommendation G.704. AV.230General Recommendation for AV system control and indications (SG XV, NDK, 1992) Outline proposed in COM XV-R 26 (Annex 1 to Part B.5). AV.231 Multipoint control of 64 kbit/s AV services (SG VIII, LD, 1992) Implementation of AV.230 in the case of calls using single 64 kbit/s paths only. Ditto, using two 64 kbit/s paths. Ditto, using ISDN to Recommendation I-Series. AV.232 Multipoint control of 384 - 2048 kbit/s services (SG XV, NDK, 1992) Implementation of AV.230 in the case of 384 kbit/s paths. Ditto, using 1544 and 2048 kbit/s paths. AV.240 Principles for communication between AV terminals (SG XV, NDK, 1989) Text proposed in COM XV-R 26 (Annex 2 to Part B.5). AV.241System aspects for the use of the 7 kHz audio codec within 64 kbit/s (SG XVIII, XM, 1988) Draft Recommendation G.72Y. AV.242System for establishing communication between AV terminals using one or two 64 kbit/s channels (SG XV, NDK, 1989) Preliminary text proposed in COM XV-R 26 (Annex 6 to Part B.5). AV.250 Audio coding AV.251 Narrow-band audio coding at 64 kbit/s G.711 AV.252 Wideband audio coding in 64 kbit/s G.722 AV.253 Audio coding at 40/32 kbit/s (SG XV, XX, 1989) (Using G.721/728 or extending G.722 down, or extending AV.254 up.) AV.254 Narrow-band speech coding at 16 kbit/s (SG XV, XX, 1989) AV.260 Video coding AV.261 AV.262 n x 384 kbit/s video codec (SG XV, SO, 1989) H.12X AV.263 m x 64 kbit/s video codec (SG XV, SO, 1989) H.12Y III. Systems and terminal equipment AV.300 General Recommendation for AV systems and terminals AV.301 General Recommendations on AV terminal equipment AV.313 Teleconference protocol (SG VIII, LD, 1992) AV.310 Requirements for teleconferencing (SG VIII, LD, 1992) AV.311 Audiographic system and terminal requirements (SG VIII, LD, 1992) Transducers. Room disposition (mainly left to customer choice). Processing (mixing, echo cancellation, voice switching, etc.). Noise specification. Audio alignment (level-setting). Subjective quality (in association with infrastructure coding options as given in AV.250 Series). AV.312 Videoconference system and terminal requirements (SG XV, SO, 1992) Transducers. Room disposition and lighting. Noise specification. Processing (mixing/split-screen, switching, etc.). Video alignment. Subjective quality (including video coding options according to AV.260 Series). AV.320 Requirements for videophone service (SG XV, SO, 1992) Generally as for videoconference, AV.312 above (differences of detail). IV. Network aspects AV.400 Multipoint call set-up (SG XVIII, XX, 1992) Purely from the network point of view, and nothing specifically to do with audiovisual services, there will be a need to ensure that multipoint calls can be set up in a suitable way from the human factor point of view. Clearly this must be closely coordinated with the requirements of teleconferencing, and of conference calls as a supplementary service to videophone and other audiovisual services (see AV.230). Charging aspects must also be taken into account. AV.410 Reservation systems (SG XVIII, XX, 1992) Rapporteurs (at April 1988) MM: MATSUMOTO Mitsuji NDK: KENYON Norman LD: DIJKSTRA Lokke XM: MAITRE Xavier SO: OKUBO Sakae XX: to be appointed ANNEX 2 (to Question 4/XV) Draft outline for Recommendation H.200/AV.200 GENERAL RECOMMENDATION FOR INFRASTRUCTURE FOR AUDIOVISUAL TELESERVICES 1. Introduction recoup ANNEX 3 (to Question 4/XV) Draft Recommendation H.200/AV.230 OUTLINE GENERAL RECOMMENDATION FOR AUDIOVISUAL SYSTEM CONTROL AND INDICATIONS Contents 1. INTRODUCTION 1. Introduction recoup 4.1 Control (C) 4.2 Indication (I) ANNEX 4 (to Question 4/XV) Draft Recommendation H.200/AV.240 PRINCIPLES FOR COMMUNICATION BETWEEN AUDIOVISUAL TERMINALS Contents 1. INTRODUCTION 5. recoup The recoup 3.2 recoup 4.2.3 recoup 5. recoup (c) recoup figure figure table ANNEX 5 (to Question 4/XV) Draft Recommendation H.200/AV.242 SYSTEM FOR ESTABLISHING COMMUNICATION BETWEEN AUDIOVISUAL TERMINALS USING ONE OR TWO 64 KBIT/S CHANNELS 1. Introduction Mode 6: recoup 2.3 + - + Type of remote terminal + 0 1 2 3 3V/1 3V/2 + + + - Type of Type 1 local MODE 1 terminal Type 2 + MODE 2 Type 3 + MODE 7 Type 3V1 + MODE 7V1 Type 3V2 + MODE 7V2 + - + FIGURE 1/AV.242 Mode of operation upon completion of the initialization procedure A second recoup 4.3 Frame recovery sequence C recoup Addition of a recoup When the terminal is receiving recoup 7. Network recoup ============================================================ Question 5/XV - Characteristics of direct transmission restoration systems of the 1+1 and N+M type (link protection switching) (Continuation of Question 8/XV 1985-88) Considering (1) that Recommendations G.180 and G.181 give the characteristics of 1+1 and N+M type systems for the direct transmission restoration of digital transmission equipment and links; (2) that these Recommendations are incomplete and include a number of provisional values; (3) that direct transmission restoration systems using non- regenerative equipment ensuring the switching of analogue as well as digital links appear to be of interest, 1. How may Recommendations G.180 and G.181 be completed? 2. May the provisional values be definitively recommended or, if not, how have they to be amended? 3. What characteristics should be recommended for direct transmission restoration systems using non-regenerative equipment ensuring the switching of analogue as well as digital links? Notes 1. The equipment studied under point 3 of the Question may be object of a separate Recommendation or included as special cases in Recommendations G.180 and G.181. 2. The study of this Question should be coordinated with the study of Questions 6/XV and 18/XV and 9/XV. ============================================================ Question 6/XV - Characteristics of automatic rerouting systems for the restoration of transmission links (network protection switching) (New Question) Considering (1) that there is a need to provide an appropriate level of redundancy to protect a network from catastrophic events and that networks need to be planned to incorporate automatic restoration and diversity in order to increase the level of network availability; (2) that various possibilities exist or may be developed to accomplish the automatic restoration of failed network elements, What characteristics should be recommended for automatic rerouting systems for transmission restoration? Points for study 1.Interworking of equipment from different manufacturers. 2.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. Notes 1.The study of this Question should be coordinated with the study of: 1.1Questions 5/XV, 18/XV and 20/XV. 1.2Question 27/II (Design alternatives for telecommunication networks). 1.3 Question 9/IV (Transmission restoration). 1.4 Question 32B/II (Restoration of failed exchanges, etc.). 2. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. ============================================================ Question 7/XV - Characteristics of network echo control equipment (Continuation of Question 10/XV 1985-88) Considering (1) that the current tests in Recommendation G.165 do not take into account many real-world signal conditions such as: 1.1 high level speech, 1.2 signalling tone, 1.3 call-processing tone, 1.4 voice band data signals, 1.5 FAX transmission, (2) that there is a tradeoff between echo path delay (td), convergence quality and convergence time that is inadequately explored in Recommendation G.165; (3) that modifications, if made, to Recommendation G.165 may improve echo canceller subjective performance; (4) that double-talk break-in and amplitude clipping can occur in echo cancellers; (5) that there may be advantages in the use of noise injection; (6) that uncertainties over the precision required of the tone disabler still remain; (7) that the canceller echo path (ROUT to SIN) may include ADPCM encoders as well as tandem PCM codings; (8) that ISDN and ISDN/PSTN interworking issues may impact on the performance and control requirements of echo control devices, 1. What tests should be added or changed in Recommendation G.165 to guarantee acceptable behaviour with high level speech, signalling tones, call- processing tones, voice band data signals, FAX transmissions and the like? (see annex); 2. What should be the recommended convergence time for echo cancellers as a function of echo path delay? 3. What signal(s) could be used instead of or in addition to white noise to better ensure that an echo canceller that passes tests with these signals results in a good Mean Opinion Score? 4. What signal or test could be used to test for situations where double- talk break-in and amplitude clipping could occur? 5. What should be recommended for noise injection in echo cancellers and what should be recommended for any related tests? 6. What degradation is there when ADPCM encoders or multiple PCM coders are used in the echo path of an echo canceller and what should be recommended in Recommendation G.165 to verify that adequate cancellation is obtained? 7. What should be recommended for network echo control devices to take account of the requirements of the ISDN? Points for study 1.Whether the performance of echo cancellers which conform to Recommendation G.165 can adversely affect narrow-band signals present on their transmission paths and, if so, how this should be taken into account. 2.The performance of network echo cancellers with speech signals that have been processed other than by being encoded according to Recommendation G.711, e.g. by low bit rate ADPCM or wideband encoding. 3.The correct operation of tone disablers - conditions under which correct operation should be expected. 4.Network echo canceller performance in the presence of signals corresponding to very loud speech. 5.ISDN requirements. Notes 1. Account may need to be taken of the study of Questions 8/XV, 21/XV and 23/XV. 2. Account should be taken of the work of Study Group XVIII on ISDN and general network issues. 3. Account should be taken of the work of Study Group XII on subjective testing issues, transmission plan aspects and actual speech level in modern networks. ANNEX (to Question 7/XV) Proposed tests currently under study for Recommendation G.165 Two tests to ensure stability with narrow-band signals (like some voice band data sets) are under study: 1) Old provisional test No. 6: The test procedure is to clear the H register and disable the nonlinear processor. Apply a sine wave (1 300 Hz + 50 Hz) at Rin, connect a detector at Sout and provide an echo loss between Rout and Sin. Requirement (provisional, under study) With the H register initially set to zero, for all values LRin > 15 dBm0 and < 10 dBm0 and present for three minutes, and for all values of echo loss > 6 dB, the residual echo level should be less than LRin 18 dB throughout the test after an initial convergence period of < 1 s. 2) Proposed new test No. 6: This test has the object of verifying that the echo canceller will stay stable for narrow-band signals. Measure the maintenance of the cancellation during and after the application of a sinusoidal wave or a wave composed of two frequencies. The method consists of completely converging the echo canceller. A mono or bifrequency signal is then applied to Rin. After three minutes the adaption is inhibited and the returned echo is measured. The non-linear processor is disabled. Conditions With the echo canceller fully converged, after application at Rin for three minutes of a mono or bifrequency signal (f1 + f2 with |f1 f2| > 170 Hz) such that LRin > -30 dBmO and < -10 dBmO and for all values of echo loss > 6 dB and echo path delay, td 170 Hz) applied at the send in port 90 ms after having applied the same signal (except for level and phase) at the receive in port, should not vary by more than 2 dB when compared to the nominal level of the injected signal. The level "N" of each frequency applied is so that -18 dBmO < N < O dBmO and the echo loss is infinitive. ============================================================ Question 8/XV - Characteristics of acoustic echo control equipment (Continuation of Question 11/XV, 1985-1988) Considering (1) that acoustic echo control is now necessary in many areas of telecommunication such as: 1.1 teleconferencing, 1.2 loudspeaking telephones, 1.3 mobile applications, 1.4 ISDN; (2) that equipment used for acoustic echo control may utilize, in part, the principles and techniques for echo control given in Recommendations G.164 and G.165; (3) that a draft Recommendation for acoustic echo control equipment has been prepared and is given in an annex to this Question, 1. What are the desirable characteristics of equipment used to control acoustic echoes in the applications listed above and what characteristics should be recommended? 2. What tests should be recommended to determine compliance with these characteristics? 3. How will speech sampled and coded using techniques which differ from those given in Recommendation G.711 affect the design of acoustic echo control equipment and what should be recommended to take proper account of this? 4. What interactions will there be between acoustic echo control equipment and network echo cancellers which conform to Recommendation G.165 and/or echo cancellers used in the ISDN digital subscriber line, and what should be recommended to keep any undesirable interactions within acceptable limits? Notes 1. Account should be taken of the work in Study Group XII on subjective testing and acoustic characteristics of the teleconference rooms. 2. Account should be taken of the work in Study Group XVIII on ISDN and general network issues. 3. Account should be taken of the studies of network echo control equipment carried out under Question 7/XV. ANNEX (to Question 8/XV) Draft Recommendation G.AEC ACOUSTIC ECHO CONTROLLERS FOR TELECONFERENCING APPLICATIONS Recoup 2. In Annex 1 3.5 4.4 5. Fig. Test 7. Annex 1 ============================================================ Question 9/XV - Operations, Administration and Maintenance (OAM) interfaces for transmission equipment intended for connection to a Telecommunications Management Network (TMN) (Continuation of Question 12/XV 1985-1988) Considering (1) that Recommendation G.771 has not been completed; (2) that transmission equipment implemented with large scale integrated circuitry and/or microprocessors is now being deployed; (3) that in addition to transmission functions this equipment has the intelligence to perform auxiliary OAM functions such as: -administration, - automatic provisioning and testing of circuits, -performance testing and diagnosing the equipment itself and the connecting line system, as defined by Study Group IV in Recommendations M.30, M.36 and M.550; (4) that this equipment may communicate with local and/or remote, computer-based operations systems to perform these auxiliary OAM functions; (5) that it may be possible (by means of suitable adaptors) to realize on existing analogue and digital transmission equipment some of the benefits arising from connection to a TMN; (6) that overhead channels are being defined for OAM purposes (for example Study Group XVIII for the digital synchronous hierarchy), 1. How should Recommendation G.771 be amended and completed? 2. What OAM features should be recommended for new transmission equipment and/or mediation devices? 3. What should be the recommended fundamental relationship between the transmission functions and the operations functions and what should be recommended for the division of these functions between the transmission equipment, mediation devices and the supporting operations system? 4. What characteristics should be recommended for OAM interfaces on transmission equipment and on any supporting mediation devices and what physical media and communications protocols should be recommended? 5. What human-machine language functions and/or messages should be recommended to manage transmission equipment in real time? 6. What characteristics should be recommended for mediation devices connected to transmission equipment (physical, functional, etc.)? 7. If more than one protocol is recommended, what selection process should be recommended for the determination of the most appropriate OAM interface on a given transmission equipment? 8. What should be recommended for the characteristics of Q Interface Adapters (as defined in Recommendation M.30) for the connection to a TMN of existing transmission equipment (analogue and digital) that does not have recommended Q interfaces? 9. What minimum set of TMN application functions would have to be implemented in different types of analogue and digital transmission equipment? 10. What application functions, required for the use of transmission equipment, should be implemented in a Q3 interface? 11. What should be the partitioning of functions and the selection of protocols for the use of overhead channel within facilities, for TMN application functions? 12. What new terms and definitions should be recommended relevant to TMN issues? Notes 1. Study Group IV has overall responsibility for the coordination of studies on TMN. 2.Study Group XI has responsibility for studying OAM interface Q3. 3. Study Group XV has responsibility for studying OAM interfaces Q1 and Q2. 4. Study Group XV has the responsibility for coordinating studies of TMN with CCIR Study Groups 4 and 9 and also with CMTT. 5. Study Group XV should liaise closely with Study Groups IV and XI in the study of this Question including the development of suitable terminology. 6. Study Groups X and IV are examining the application of human-machine interface for OAM. 7. Parts 8 and 9 of Question 9/XV and parts 2.3 and 2.5 of Question 26/XV deal with transmission equipment according to existing Recommendations and should be studied together. ============================================================ Question 10/XV - Characteristics of Digital Circuit Multiplication Equipment (DCME) and Systems (DCMS) (Continuation of Questions 13/XV and 31/XVIII, 1985-1988) Considering (1) that Recommendation G.763 currently addresses the functional requirements for a DCME based on the encoding algorithms of Recommendations G.721 and G.723; (2) that this Recommendation has outstanding items and provisional values; (3) that the intent is to provide a Recommendation which will ensure full compatibility between equipments made by different manufacturers; (4) that the Recommendation is intended to be applicable to both satellite and cable systems and should include point-to-point and multipoint applications and the various signalling systems; (5) that the information currently available to the CCITT includes that in the documents listed in Supplement 1 to Recommendation G.763; (6) that administrations and other authorities are also studying detailed specifications for DCME and DCMS; (7) that there may be a future Recommendation for a 16 kbit/s speech encoding algorithm (see Question 21/XV), 1. How should Recommendation G.763 be expanded and finalized while achieving full compatibility for the various applications? 2. How should studies of DMCE in the CCITT be coordinated with those being carried out by other authorities? 3. What should be recommended in DCME to ensure correct operation of a DCMS in a network, e.g. ISDN? 4. How should Recommendation G.763 be modified and what new Recommendations may be desirable considering the algorithms which may result from the study of Question 21/XV? 5. Is 16 kbit/s overload channel operation desirable, and if so, how should Recommendations G.723 and G.763 be modified to accommodate this? Points for study 1.Network considerations and constraints affecting the DCME design. 2.Equipment implications of tandem operation of DCMS in a network. 3.DCME frame structure and protocols. 4.Slip buffer effects. Notes 1. The study of this Question should be coordinated with: 1.1 Study Group XII on subjective testing issues. 1.2Study Group XI on network telephone switching and signalling issues. 1.3Study Group XVIII on general network issues. 2. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 3. The study of this Question should start with the INTELSAT, EUTELSAT and T1 specifications used as basic source documents, together with any further contributions from other bodies and administrations both for setting study priorities and as technical proposals. ============================================================ Question 11/XV - Characteristics and test methods for single-mode optical fibre cables (Continuation of Question 22/XV 1985-88) Considering (1) that existing Recommendations G.652, G.653 and G.654 have some items that are still open for further study; (2) that requirements for Reference Test Methods and Alternative Test Methods contained in Recommendations G.652, G.653 and G.654 have some items that are still open for further study; (3) that particular applications, e.g., submarine cables, local networks and coherent transmission systems, may require appropriate choice of fibre types; (4) that other types of single-mode fibres (e.g. mid-infrared fibres, polarization maintenance fibres) are at present under consideration; (5) that the requirements of those private networks which include elements of public networks may need to be taken into account; (6) that there may be requirements for additional Reference Test Methods for measuring other characteristics of optical cables with single-mode fibres; (7) that there may be requirements for additional practical, simple and cost effective Alternative Test Methods for factory and field applications, 1. How should Recommendations G.652, G.653 and G.654 be amended and completed? 2. What new Recommendations should be prepared for other types of single- mode optical fibres? (e.g. dispersion flattened fibres, polarization maintaining fibres, mid-infrared fibres); 3. What additional Reference Test Methods and Alternative Test Methods need to be established? 4. Where should definitions and test methods be located? Points for study 1.The interrelationship between fibres parameters and transmission characteristics. 2.The interrelationship between the transmission properties of cable factory lengths and elementary cable sections. 3.Geometrical, optical and transmission characteristics of different single-mode optical fibres. 4.Mechanical aspects of fibres and splices. 5.Reliability in various environmental conditions. 6.The extent to which transmission characteristics are affected by: -the make-up of cables -methods of installation - methods of jointing - maintenance methods. 7. The need for additional Reference Test Methods. 8.The need for additional Alternative Test Methods for factory and field applications. 9.Fibre characteristics for possible operation with wavelength division multiplexing systems with bidirectional transmission and coherent systems. Notes 1 The study of optical fibres for submarine systems should be coordinated with the study of Question 13/XV. 2. The study of optical fibres for the local network should be coordinated with the study of Question 14/XV. 3. The study of this Question should be coordinated with the study of Question 18/XV. 4.The study of points 4 and 6 should be coordinated with Study Group VI. ============================================================ Question 12/XV - Characteristics and test methods for multimode optical fibre cables (Continuation of Question 21/XV 1985-88) Considering (1) that existing Recommendation G.651 which gives characteristics and test methods for 50/125 5 m graded index optical fibre cables is based on the technology used with source wavelengths around 850 nm and 1300 nm; (2) that requirements for Reference Test Methods and Alternative Test Methods are also contained in Recommendation G.651; (3) that particular applications, e.g. local networks, may require appropriate choice of different fibre types and dimensions; (4) that the requirements of those private networks which include elements of public networks may need to be taken into account; (5) that Recommendation G.651 has some items that are still open for further study, 1. How should Recommendation G.651 be amended and completed? 2. What new Recommendations should be prepared for other types of multi- mode optical fibres? 3. What additional Reference Test Methods and Alternative Test Methods need to be established? 4. Where should definitions and test methods be located? Points for study 1.The interrelationship between fibre parameters and transmission characteristics. 2.The interrelationship between the transmission properties of cable factory lengths and elementary cable sections. 3.The geometrical, optical and transmission characteristics of different multimode optical fibres. 4.Possible operation - at around 1550 nm - with bidirectional transmission - with wavelength division multiplexing. 5.Mechanical aspects of fibres and splices. 6. Reliability in various environmental conditions. 7. The extent to which the transmission characteristics are affected by: - the make-up of cables - methods of installation - methods of jointing - maintenance methods. 8.The need for additional Reference Test Methods. 9.The need for Additional Alternative Test Methods for factory and field applications. Notes 1. The study of points 5 and 7 should be coordinated with Study Group VI. 2. The study of optical fibres for the local network should be coordinated with the study of Question 14/XV. 3. The study of this Question should be coordinated with the study of Question 18/XV. ============================================================ Question 13/XV - Characteristics for submarine optical fibre cables and systems (Continuation of Question 19/XV 1985-88) Considering (1) that the characteristics of optical fibres and the progress in opto- electronic components make it possible to realize submarine cable links with optical fibres; (2) that many administrations are now using such submarine cable links; (3) that optical fibre intended for submarine cables use need to have characteristics appropriate to the special mechanical and environmental conditions that they are likely to encounter; (4) that long lengths of cable are generally used in submarine applications, What should be recommended for the characteristics of submarine optical fibre cables and systems? Points for study 1.Transmission characteristics and relevant test methods for long-length fibre and cable. 2.Mechanical characteristics of fibre and cable. 3.Reliability under various environmental conditions of: 3.1optical and transmission characteristics of fibre and cable; 3.2 mechanical properties of fibre and cable. 4.Maintenance strategy. 5.Line systems aspects. Notes 1. The study of this Question should be coordinated with the study of Questions 11/XV, 18/XV and 25/XV. 2. Study of Point 2 should be coordinated with Study Group VI. 3.Study of Point 4 should be coordinated with Study Group IV. 4. It would be useful to keep up to date the information on cable ships given in the Blue Book, Volume III, Supplement 11. 5. The summary of the data collected during the 1985-88 study period on the characteristics of submarine cables are given in the optical fibre systems Planning Guide. ============================================================ Question 14/XV - Characteristics of optical cables for local networks (Continuation of Question 18/XV 1985-88) Considering (1) that optical fibres can provide narrow-band and broadband/high bit rate services which can be of conventional, interactive and distributive type; (2) that many administrations are already deploying such systems, e.g. for business communications applications; (3) that there is the need to provide such systems by means of suitable optical fibres; (4) that such applications in the local network are highly cost sensitive; (5) that systems in the local network are generally of short range, What characteristics should be recommended for optical cables for narrowband and broadband high bit rate services in telecommunications local networks? Points for study 1.The relationship between the required cable performance and factors such as network structure, the intended applications and installation practices. 2.Factors allowing for cost reductions. 3.Environmental conditions. 4. Maintenance aspects. Notes 1. The study of this Question should be coordinated with the study of Questions 11/XV, 12/XV, 16/XV and 18/XV. 2. The installation practice under point 1 should be coordinated with Study Group VI. 3. Account should be taken of the studies of narrow-band and broadband ISDN undertaken by Study Group XVIII. ============================================================ Question 15/XV - Characteristics of line systems on optical fibre cables (Continuation of Question 24/XV 1985-88) Considering (1) that a number of Recommendations in the G.900-Series give characteristics for digital line systems on optical fibres; (2) that the operational experience relating to optical fibre systems is now rapidly increasing; (3) that advances in the technology of optical fibres and components may make feasible new generations of line systems on optical fibres, (e.g. analogue systems, high bit rate systems, wavelength division multiplexing systems, coherent systems); (4) that optical fibres may be used for in-station cabling, 1. How should Recommendations G.955 and G.956 be amended and completed? 2. How should tables in Recommendation G.955 and in Recommendation G.956 giving optical path allowances be completed? 3. How should other existing Recommendations in the G.900-Series be amended and completed insofar as they relate to digital line systems on optical fibres? 4. What new Recommendations should be established regarding new generation line systems on optical fibres? 5. What should be recommended for optical fibre in-station cabling? Points for study 1. High bit rate systems. 2. Dispersion limited systems. 3. Single-mode fibre systems employing LEDs, MLM lasers and SLM lasers. 4. 1550 nm wavelength systems. 5. Systems not optimized for maximum section length. 6. Wavelength division multiplexing. 7. Systems employing coherent detection. 8.Possible power feeding arrangements and related precautions against induced voltages and currents. 9.Environmental conditions, if some other studies appear necessary. 10. Overall design features. 11.Implications of IEC studies of optical fibre/laser safety considerations. 12.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 13.Design methodology - worst case versus statistical design approach. 14. Definitions and test methods of system/equipment parameters. 15.Error performance of operational systems - see annex to this Question. 16.Requirements for systems/equipment characteristics which provide transverse compatibility in order to enable equipments designed by different manufacturers to interwork and/or be utilized together in a given digital line system (i.e. the possibility of mixing various manufacturers' equipment within a single digital line system) including optical pulse shape and optical source parameters. 17.Definitions and test methods. 18.The requirements for systems operating on fibres conforming to Recommendations G.651, G.652, G.653 and G.654. 19.The use of optical fibres for in-station cabling. 20.Enhancements to the maintenance strategy requirements of section 8 of Recommendations G.955 and G.956. 20.1Monitors and alarms. 20.2 Supervision and fault location. 20.3 Protection switching. 20.4 Engineering and wiring. 21. Line systems employing optical amplifiers. Notes 1. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 2. Protection switching systems are studied under Questions 5/XV and 6/XV. 3. The study of this Question should be coordinated with the study of Questions 11/XV, 12/XV, 18/XV, 16/XV, 25/XV and 29/XV. 4.Study Group XVIII is responsible for general network issues. 5. Study Group V is responsible for the study of protection against dangers and disturbances of electromagnetic origin. 6. The study of digital sections, if any, should be carried out under this Question and coordinated with the study on systems of CCIR Study Groups 4 and 9. ANNEX (to Question 15/XV) Optical line system error performance In response to a request from Study Group XVIII for the involvement of Study Group XV in error performance studies, it was recognized that information on the distribution of errors in digital line systems was required. This information was considered desirable to provide data on error occurrence, burst error length and possible loss-of-alignment and also to enable comparison of any background error ratio with error threshold requirements. The following questionnaire was prepared to obtain relevant data. Questionnaire on optical line system error performance - system bit rate - physical support (optical fibre cables) - section length and number of repeaters If possible, carry out the measurements on systems with a length near to that of the digital sections (50 or 280 km) - link characteristics (operational system, field trial, laboratory experiment) - system characteristics (e.g. source type, receiver type) - information concerning: - binary BER - pseudo-random sequence (refer to 0.151) - line code BER - multiplication factor (theoretical and measured) - does the equipment allow: - to record the sending of AIS - to record equipment faults indication - quality classification (class 1 or other) - if necessary, translation rule used, in term of length, between the measured section and HRDS objective for the considered quality classification - measurement time - measurement method (test configuration details) - percentage of: (at 10-6 (for information) ( degraded minutes: (at 10-7 ( (at 10-8 Errored Seconds (ES) Severely Errored Seconds (SES) - time of occurrence of errored seconds (in seconds) - number of errors in each errored second Note 1 - Data should be measured at the system bit rate. Note 2 - For the degraded minutes, it is suggested to use a translation parameter, from the system bit rate to 64 kbit/s channel, equal to one. For ES and SES the translation rule should be indicated. * * * Information received during the 1985-1988 study period indicated that a BER design objective of 1.10-10 is required to meet Recommendation G.821 requirements and that this objective could be readily met. Replies to the questionnaire, available during the 1985-1988 study period, generally refer to relatively short periods of time (a few hours or days) compared to the averaging periods in Recommendation G.821. Further study based on the questionnaire is required in the 1989-1992 study period to provide a statistically significant data base. ============================================================ Question 16/XV - Characteristics of digital line systems for use in local networks including narrow-band and broadband ISDN access (Continuation of Question 25/XV 1985-88) Considering (1) that Recommendation G.961 specifies the digital line systems on metallic pairs for basic rate access to ISDN; (2) that Study Group XVIII has specified the basic requirements for primary rate access; (3) the increasing need for distributive broadband services such as television and sound programme; (4) the future need for interactive broadband services such as visual telephony and videoconferencing; (5) that the preliminary requirements for ISDN services have been established; (6) the functional characteristics and reference configuration for broadband ISDN are being defined by Study Group XVIII; (7) that the general network aspects such as network structure, reference configurations, network performance objectives, etc. will be further studied by Study Group XVIII; (8) the possibilities offered by digital techniques and optical fibres etc. for the transmission of digital signals in local networks; (9) that the impact of private networks which include elements of public networks need to be taken into account; (10) that Recommendation G.960 specifies digital section for basic rate access and that specific digital line sections may require further work; (11) that a new synchronous digital hierarchy is under study in Study Group XVIII, 1. What characteristics should be recommended for digital line systems on optical fibre cables to be used in local networks including narrow- band and broadband ISDN access? 2. What characteristics should be recommended for any optical interfaces in local networks? Points for study 1.Transmission media, e.g. fibre type. 2. Transmission method. 3. Transmission path interfaces. 4. Error performance. 5. Jitter performance. 6. Availability. 7. Reliability. 8. Environmental conditions, if some other studies appear necessary. 9. Maintenance strategy. 10. Monitoring capabilities. 11.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 12.Protection against interference. Notes 1. Account should be taken of the study of ISDN carried out by Study Group XVIII including any access bit rates and other characteristics that may be recommended by them for the local network. 2. The study of this Question should be coordinated with the study of Questions 14/XV, 15/XV, 17/XV, 18/XV, 25/XV. 3. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 4. Study Group V is responsible for the study of protection against dangers and disturbances of electromagnetic origin. 5.Study Group XVIII is responsible for general network issues. 6. Study on digital sections, if any, should be carried out under this Question and coordinated with the studies on systems of CCIR Study Groups 4 and 9. 7. Studies of this Question should be coordinated with Question 20/XVIII. ============================================================ Question 17/XV - Characteristics of coding (e.g. PCM, ADPCM) and digital multiplexing equipment for use in local networks including narrow-band and broadband ISDN access (New Question) Considering (1) that many administrations are already deploying broadband/high bit rate systems in their local networks to provide, for example, business communications services, audiovisual services, etc.; (2) that such applications in the local network are highly cost sensitive; (3) that broadband ISDN is being studied by Study Group XVIII; (4) that transmission equipment already recommended is, in general, optimized for use in main networks and the special requirements of the local network may not have been taken into account; (5) that systems in the local network are generally of short range; (6) the possibilities for broadband transmission offered by optical fibres, What characteristics should be recommended for coding and digital multiplexing equipment for use in local networks? Points for study 1.Applications and performance requirements. 2.The types of equipment required, e.g. multiplexing 64 kbit/s access, low bit rate encoding, broadband access, etc. 3.Type of service to be carried, e.g: - PSTN circuits - analogue private circuits - analogue data circuits - digital private circuits - digital data circuits - broadband circuits. 4. Characteristics of electrical interfaces. 5. Bit rates/signals to be accommodated at transmission interfaces. 6. Cost reduction measures. 7. Size and modularity. 8. Time slot access flexibility/time slot interchange. 9. Programmable/remote control facilities. 10. Environmental conditions if some other studies appear necessary. 11. Maintenance aspects. 12.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 13. Network constraints and considerations. Notes 1. Any equipment recommended should be able to meet, or be capable of evolving to meet, any relevant broadband requirements that may be recommended by Study Group XVIII. 2. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 3. The study of this Question should be coordinated with the study of Questions 16/XV and 18/XV. 4. Account may need to be taken of the studies of Questions 1/XV, 2/XV, 3/XV, 4/XV, 19/XV and 20/XV. 5. Account should be taken of the studies of ISDN (including any access bit rates), the new synchronous hierarchy and general network issues carried out by Study Group XVIII. ============================================================ Question 18/XV - Availability and reliability of line systems on optical fibres (Continuation of Question 28/XV 1985-88) Considering (1) that the reliability of digital systems on optical fibre is of importance in achieving an adequate service availability on the transmission paths or channels routed on those systems; (2) that a wide range of factors impact on the reliability that can be achieved; (3) that proposals have been made concerning reliability and availability issues, including their definition; (4) that the greater the use of fibre systems bandwidth the higher the cost of system outage; (5) that the cost due to a poor quality (reliability/availability) may amount to a significant percentage of the material costs, 1. What should be recommended for reliability and availability objectives for line systems on optical fibres? 2. What should be recommended for reliability and availability objectives for the hardware and software elements making up line systems on optical fibres? 3. What definitions should be recommended to ensure that field-related experience about failure modes, and their effects, could be timely used to improve the quality of fibre optic systems? Points for study 1.The definitions related to availability and reliability issues as applied to line systems on optical fibres. 2.Cost optimized procedures for the allocation of availability objectives for the various parts of a system. 3.The need to set availability and reliability objectives for the various elements that may make up a line system on optical fibres, e.g.: - cable - regenerators - multiplexing equipment - terminating equipment - power supplies - protection switching equipment. 4.Systems architecture, cable routing and redundancy. 5.Maintenance procedures. 6.Environmental conditions. 7.Uncontrollable natural phenomena, e.g.: - lightning - flooding - ice loading. 8.Procedures and examples showing the calculations necessary to determine the appropriate allocations of availability and reliability objectives to the system elements, (examples of these elements are given in point 3 above). Calculation of examples covering long-distance, inter- exchange and local network applications would be useful. 9.Measuring procedures for assessing reliability/availability objectives as applied to line systems on optical fibres. Notes 1. Study Group II is responsible for coordinating the study of reliability and availability. 2. The study of this Question should be coordinated with the study of Questions 5/XV, 6/XV, 11/XV, 12/XV, 13/XV, 14/XV, 15/XV, 16/XV, 17/XV, 19/XV, 25/XV and 29/XV. ============================================================ Question 19/XV - Characteristics of digital multiplexing equipment for the synchronous hierarchy Considering (1) that Recommendation G.707 gives the hierarchical bit rates for the synchronous hierarchy; (2) that Recommendation G.708 gives a Network Node Interface for a synchronous hierarchy; (3) that Recommendation G.709 gives the basic method to be used for multiplexing signals at the hierarchical bit rates given in Recommendation G.707; (4) that there will be a need in the synchronous digital hierarchy for multiplexing equipment operating at the hierarchical bit rates given in Recommendation G.707, conforming to the basic multiplexing method given in Recommendation G.709 and conforming to the interface specification given in Recommendation G.708; (5) that existing Recommendations in the G.700-Series give characteristics for multiplexing equipment used for multiplexing signals into hierarchical bit rates given in Recommendation G.702, What should be recommended for the characteristics of multiplexing (including add/drop multiplexing) equipment for the synchronous hierarchy? Points for study 1.The signals or groups of signals that should be accommodated at the tributary side of the multiplexing equipment. 2.Characteristics of transmission electrical interfaces. 3.Bit rates that should be accommodated at the transmission interfaces on the multiplexed side. 4.Size and modularity. 5.Synchronization interfaces. 6.Overhead processing. 7.Pointer characteristics. 8. Environmental conditions, if some other studies appear necessary. 9.Maintenance aspects. 10.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 11.Information and control signals that may need to be passed between multiplexing equipment and this type and a Telecommunications Management Network (TMN). Notes 1. Operations, Administration and Maintenance interfaces on transmission equipment is carried out under Question 9/XV. 2. Account should be taken of the studies of the synchronous hierarchy being undertaken by Study Group XVIII. 3. The study of this Question should be coordinated with the study of Question 18/XV. ============================================================ Question 20/XV - Characteristics of digital cross-connect equipment Considering (1) that there is a need at digital network nodes for the flexible cross-connection, at different hierarchical levels, of channels, groups of channels and digital links; (2) that studies of the new synchronous hierarchy include cross- connect arrangements; (3) that progress in studies of digital network structures may result in the interconnection of network terminations without the use of digital exchanges being recommended for certain applications; (4) that Recommendation G.707 gives the hierarchical bit rates for a new synchronous hierarchy; (5) that Recommendation G.708 gives a Network Node Interface for a new synchronous digital hierarchy; (6) that there is a need to interconnect signals between systems operating at 1544 kbit/s and 2048 kbit/s. (7) that there is a need to transport and distribute broadband signals in digital networks, 1. What should be recommended for the characteristics of synchronous cross-connect equipment for digital signals, and groups of signals? 2. What should be recommended for the characteristics of plesiochronous cross-connect equipment for digital signals? Points for study 1.The signals, groups of signals and digital link bit rates that should be switched. 2.Characteristics of transmission electrical interfaces. 3.The multiplexed bit rates required at the transmission interfaces. 4. Size and modularity. 5. Synchronization interfaces. 6. Overhead processing. 7. Pointer characteristics. 8.Environmental conditions, if some other studies appear necessary. 9. Maintenance aspects. 10.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 11.The types of data channel required between cross-connect equipments and a Telecommunications Management Network (TMN). 12.The type of information, signalling and control signals that may need to be exchanged between cross-connect equipment and a TMN. Notes 1. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 2. Account should be taken of the studies of the new synchronous hierarchy being undertaken by Study Group XVIII. ============================================================ Question 21/XV - 16 kbit/s speech signal encoding and extension to other bandwidths and bit rates (Continuation of Question 27/XVIII 1985-88) Considering (1) that a number of sophisticated coding algorithms for speech can provide reasonable speech quality at a bit rate of 16 kbit/s; (2) that the rapid progress of LSI circuit technologies makes it possible to substantially reduce the cost and size of codec hardware to perform such sophisticated processing; (3) that it may be possible to extend the coding to provide wideband speech at 32 kbit/s; (4) that it is envisaged that several areas need low bit rate speech to reduce transmission cost, radio frequency bandwidth for mobile radio, storage capacity for store-and-forward messaging and to provide economic wideband speech transmission for audiovisual services, etc., 1. What encoding algorithm(s) should be recommended for speech coding at a bit rate of 16 kbit/s? 2. What should be recommended to allow extension to other bandwidths and bit rates? 3. What should be recommended for transcoding between 16 kbit/s encoding and 64 kbit/s PCM in accordance with Recommendation G.711? 4. What should be recommended for transcoding between 16 kbit/s encoding and 32 kbit/s ADPCM in accordance with Recommendation G.721? 5. What testing conditions and testing methods should be recommended to verify the relevant performance of equipment that incorporates the recommended algorithm(s)? Points for study 1.The applications and performance requirements that should be considered. 2.Extension to provide wideband speech at 32 kbit/s. 3.Whether it is possible to realize tandeming without any serious quality degradations. 4.The testing conditions and testing methods that should be used to select the encoding algorithm(s) to be recommended. 5.Whether the audio frequency characteristics should be specified. 6.Whether there is a need to take into account voice band signals other than speech, e.g., voice band data, facsimile, etc., for the definition of the algorithm(s) and, if so, the performance requirements for these signals. 7.Network constraints and considerations, e.g. delay and interaction with echo control. Notes 1. Account should be taken of the work in Study Group XII on speech performance aspects of digital systems and integration of mobile systems into the public switched networks, and subjective evaluation. 2. Account should be taken of the work in Study Group XVIII on ISDN and general network issues. 3. Account should be taken of the work in CCIR Study Group 8 on Programme 40A/8. 4. Account should be taken of the studies carried out under Questions 3, 4 and 10/XV. ANNEX (to Question 21/XV) Terms of reference of the ad hoc Group on 16 kbit/s speech coding Study Group XVIII agreed to set up an ad hoc Group on 16 kbit/s speech coding with the following terms of reference: 1. To select a unique coding algorithm for the achievement of a CCITT standard by the mid of next study period (mid 1991) in order to submit the draft Recommendation on this standard to the accelerated procedure. The selected algorithm should have universal application and be implemented by service and network providers with minimum integration difficulty. 2. The performance requirements and objectives for such unique coding algorithm are given in Appendix 1. 3. The assessment criteria and selection rules for the candidate coding algorithms will be as follows: a) candidate algorithms must meet the requirements; b) all algorithms meeting the requirements will then be ranked according to two main criteria: i) the margins on the various requirement parameters; ii) the capability to meet the performance objectives. The detailed working criteria have to be defined before the competitive phase. 4. The ad hoc Group on 16 kbit/s speech coding should be closely coordinated with the ad hoc Group on speech quality set up by Study Group XII, as far as quality objectives and test methodology are concerned. 5. The tentative work plan of the ad hoc Group is given in Appendix 2. According to this plan the Group should report on the progress reached at the first meeting of Study Group XV (S N) likely in April/May 1989. In particular, the Group should advise Study Group XV on the concrete possibility to reach the unique CCITT standard for universal applications of 16 kbit/s speech coding. In case this goal is reachable, Study Group XV should confirm the remaining work plan. In case such a goal appears to be not feasible, Study Group XV should consider whether the standardization of a limited number of application-dependent solutions is feasible and define new goals and work plans. 6. Network aspects should be reported to Study Group XVIII at its first meeting in 1989. 7. A list of possible network applications for 16 kbit/s speech coding is given in Appendix 3. It is agreed that an algorithm, that meets the requirements and reaches to a large extent the objectives set up in Appendix 1 could meet reasonably well all applications listed in Appendix 3, even though it might not be optimal for a certain application. A possible clarification of more significant applications listed in Appendix 3 regarding specific performance objectives and requirements is the following: i) videophone and store and forward applications; ii) digital mobile radio, cordless telephones and low C/N satellite system applications; iii) DCME, PSTN and ISDN applications. Mr. R. Pietroiusti (SIP, Italy) was appointed Chairman of the ad hoc Group on 16 kbit/s speech coding. Appendix 1 (to Annex to Question 21/XV) Performance requirements and objectives for the CCITT standard on 16 kbit/s speech coding algorithm TABLE 1 + - + PARAMETER REQUIREMENTS OBJECTIVES + - + + Speech quality in qdu's1 For an input signal - nominal level of -22 dB with respect to the overload point: - BER < 10-6 < 4.02 random errors - BER < 10-3 Not worse than that random errors of G.721 under similar conditions3 4 - BER < 10-2 Not worse than that random errors of G.721 under similar conditions3 + - + + Speech quality dependency To be defined. (It As low as possible on the input signal level will be provided between -32 dB and -12 dB by SG XII) with respect to the over- load point + - + + One way coder/decoder delay in ms5 < 5 < 2 + - + TABLE 1 (Cont.) + - + PARAMETER REQUIREMENTS OBJECTIVES + - + + Encoder/decoder To be defined - synchronization6 Capability to transmit - Data at bit rates as high as voice-band data possible with satisfactory BER Capability to transmit7 DTMF, CCITT No. 5 The tones have to be trans- signalling/information CCITT No. 6 (circuit mitted with distortion as low tones continuity tone) as possible CCITT No. 7 (circuit continuity tone) CCITT R28 Q.35, Q.23, V.25 Capability to transmit - No annoying effects have to music9 be generated Gross bit rate, 16 - kbit/s10 11 Tandemming capability 3 asynchronous with Synchronous tandemming for the speech a total distortion property < 14 qdu Tandemming capability - 3 asynchronous for the voice-band data Effects of the switching for further study12 transients following data discrimination Convergence time - < 10ms13 Capability to operate - Graceful speech quality at different bit rates degradation when operating at lower bit rates Complexity14 - As low as possible + - + Notes to Table 1 1. The numbers of qdu's are averaged values for a number of subjective tests and conditions. The average procedure through appropriate weightings of the tests and conditions will be provided by Study Group XII. 2. The requirements and the objectives of the qdu refer to the distortion introduced between the input PCM (A/5 law) interface of the coder and the output PCM (A/5 law) interface of the decoder. So, the distortion allowance for the algorithm is 3 qdu. 3. The actual figures of the distortions in these conditions will be spelt out in terms of qdu's in the course of the subjective tests. 4. In the definition of the test conditions, it will be necessary to take into account that this BER condition has not to be represented as a permanent normal condition; rather it has to be interpreted as a condition that, in probabilistic terms, does not occur in e.g. 95% of the time. 5. The delay values refer to the delay introduced by the algorithm between the input and output uniform PCM interfaces. To evaluate the overall codec delay, the expected delay due to the PCM coding, implementation processing and serial transmission at 16 kbit/s has to be taken into account and it will be an important item in the codec selection process. 6. It may be assumed that an external 8 kHz timing signal will be available (e.g. from the 64 kbit/s octet structure). This timing signal may be used to directly develop a 2 bit frame at 16 kbit/s which may be compatible with some algorithms. If the algorithm requires a frame length greater than 2 bit, an internal frame is required within the 16 kbit/s gross bit rates. The performance of the frame alignment strategy of such an internal frame will require specification. It should also be noted that the 16 kbit/s gross bit rate will be exposed to controlled octet slips when carried in 64 kbit/s channels, and the internal frame alignment strategy should allow for this. 7. The actual distortion requirements and objectives for the tones to be transmitted are for further study. 8. It should be noted that CCITT R2 Signalling System requires also the transmission of outband tones (e.g. 3 825 Hz). Methods to transmit these outband tones are for further consideration. 9. Music (both from the radio and electronically generated) is often used in PABX systems when calls are transferred or put on hold. 10. The gross bit rate is inclusive of any overheads for algorithmic functions (e.g. synchronization and possible error correction to meet the speech quality requirements/objectives). It does not include any further overheads for transmission channel dependent functions (e.g. radio channel coding). 11. The transmission delay due to the possible use of error correcting codes for algorithmic purposes (see Note 10) would be included in the limits specified for the one-way coder/decoder delay. 12. The effects of the switching transients following the data discrimination will likely be perceived as an impulse noise (clicks) rather than a qdu degradation. They depend, among other things, on the coder/decoder delay and on the covergence time of the algorithm. 13. A short convergence time is necessary to avoid speech clipping. 14. Early evaluation of the complexity will be performed on the basis of the detailed level description of the algorithms (e.g. number of multiplications, number of shifts, etc.). Appendix 2 (to Annex to Question 21/XV) Tentative work plan of the ad hoc Group activities Meeting Activities time - 5-12 December '88 - Agreement on methodology to classify codec (Florida, USA) performance: assessment, routing and selection criteria; -definition of test conditions for the competitive phase taking into account the input from the Study Group XII ad hoc Group; -preliminary declaration of intention to submit candidate algorithms; -discussion on the need to limit the number of candidates; -discussion on patent aspects; -organization of the laboratory sessions for the competitive phase; -specification of hardware models; -definition of host-laboratory facilities; -definition of the way to describe the algorithms and to evaluate their complexity. April '89 -Submission of high-level description of candidate algorithms; -submission of test results for the candidate algorithms by proponents; -possible reduction of the number of candidates on the basis of the capability to meet performance requirements; -report to Study Group XV (Study Group N) first meeting on the possibility of reaching a unique CCITT standard for universal applications of 16 kbit/s speech encoding. Spring '89 First meeting of Study Group XV (Study Group N). At this meeting Study Group XV should either confirm the following plan of the ad hoc Group or define alternative goals and plans. October/November '89 -Submission of detailed description of candidate algorithms; -laboratory session for the first round of tests. April '90 -Comparison of test results; -evaluation of algorithm complexity; -selection of 1 (2) candidate(s) for further consideration (the selected candidate at this stage could not necessarily be identical to one of the source candidates due to possible compromise mixture); -definition of testing methodology for the final round of tests. October '90 -Agreement on the selected algorithm; -organization of the final round of tests. November '90 -Laboratory session for the final round of tests. March '91 -Evaluation of the results of the final tests; -preparation of the draft Recommendation; -preparation of the report to Study Group XV. April/May '91 -Submission of draft Recommendation to Study Group XV. Appendix 3 (to Annex to Question 21/XV) List of possible applications The following applications were agreed for 16 kbit/s voice coding: 1. videophone service using transfer rates 64, 2 x 64, 128 kbit/s; 2. cordless telephone; 3. low C/N digital satellite systems. This includes maritime, thin- route and single channel per carrier satellite systems; 4. DCME. In this equipment 16 kbit/s speech coding is generally combined with DSI techniques. The equipment may be used for long terrestrial connections and for digital satellite links generally characterized by high C/N ratios; 5. PSTN. This application covers the encoding of voice telephone channels in trunks, junction or distribution networks (e.g. transcoder equipment); 6. ISDN. Distinguishing features with respect to PSTN for setting 16 kbit/s speech coding requirements are the availability of unrestricted end-to-end digital bearer capabilities, absence of electrical echo control devices and availability of SS No. 7; 7. digital leased lines. Two possibilities may be envisaged in this case; one is where the end-to-end digital leased circuits include only one encoding/decoding, the other is where the end-to-end digital leased circuits are connected into the public network and they may include digital transcodings; 8. store and forward systems; 9. voice messages for recorded announcements; 10. land Digital Mobile Radio (DMR) systems; 11. packetized speech; 12. audio channel for low bit rate one-way video service (e.g. surveillance). ============================================================ Question 22/XV - Encoding for stored digitized voice signals (Continuation of Question 29/XVIII 1985-88) Considering (1) that for the purpose of providing voice or multi-media store and forward messaging a method of representing voice as a bit string for storage and transmission purposes is required; (2) that the encoding scheme should provide a low bit rate output in order to decrease the cost of message storage and, to a lesser extent, of transmission; (3) that the decoding scheme should operate in real time and that the costs should not be too high; (4) that the voice quality should not be significantly different from current 64 kbit/s PCM transmission, What encoding scheme should be recommended for voice in the context of store and forward messaging? Points for study 1.The possibility of the scheme providing, or being able to evolve to, a very low bit rate algorithm, perhaps by silent period suppression. 2.The possibility of keeping costs down by the specification of an algorithm which can be implemented on a single IC. Notes 1. Multiple conversions, e.g. analogue-to-digital and back-to-digital, will not be required. 2.Voice band data will not have to be carried. 3. Algorithms developed under Questions 21/XV and 23/XV could also be used for the encoding of stored voice, especially when associated with suitable methods for silent periods suppression. 4. Account should be taken of the work of Study Group XVIII on the ISDN and general network issues. 5. Account should be taken of the work of Study Group XII on subjective testing issues. ============================================================ Question 23/XV - Encoding of speech signals into bit rates of less than 16 kbit/s (Continuation of Question 32/XVIII 1985-88) Considering (1) that progress in the studies of speech signal encoding indicate that reasonable speech quality may be possible at bit rates significantly less than 16 kbit/s, e.g. 8 kbit/s; (2) that certain areas of communications may have applications for speech signal encoding at bit rates of less than 16 kbit/s, 1. What bit rate(s) less than 16 kbit/s should be recommended for encoded speech signals? 2. What algorithm(s) should be recommended for encoding speech signals into this (these) bit rate(s)? 3. What test methods and conditions should be recommended to test the relevant performance of hardware which incorporates the recommended algorithm(s)? 4. What should be the recommended area(s) of application of the recommended algorithm(s)? 5. What should be recommended to allow extension to other bandwidths? Points for study 1.The application and performance requirements that should be considered. 2.The test methods and conditions that should be used to select any encoding algorithm(s) to be recommended. 3.The assessment measures that should be used to evaluate the quality of speech processed using the recommended algorithm(s); 4.Speech analysis/synthesis techniques. 5.Network considerations and constraints, e.g. delay and interaction with echo control. 6. Extension to provide wide bandwidth speech. Notes 1. Account should be taken of the work in Study Group XII on speech performance aspects of digital systems and integration of mobile systems into the public switched networks, and subjective evaluation. 2. Account should be taken of the work in Study Group XVIII on ISDN and general network issues. 3. Account should be taken of the studies carried out under Questions 3, 4 and 10/XV. 4. INMARSAT have reported activity within the Airlines Electronic Engineering Committee on codecs operating at 4.8 to 9.6 kbit/s for use in telephone communications in commercial airlines. 5. Land mobile satellite use of voice codecs operating between 4.8 and 9.6 kbit/s is also subject to activities in several organizations for commercial telephone communications. ============================================================ Question 24/XV - Speech packetization systems (Continuation of Question 32/XVIII 1985-88) Considering (1) that packet switched services are widely provided through the nation-wide and world-wide telecommunication networks as well as small- scale local area networks; (2) that it may be desirable to handle not only data but also speech in packet switched networks to improve the serviceability of the networks; (3) that studies on speech packetization are being widely performed and that the performance of packetized voice is being analyzed to some extent, 1. What coding algorithm(s) and bit rate should be recommended for use in speech packetization systems? 2. What packetization techniques should be recommended? 3. What protocol characteristics at Layers 2 and 3 should be recommended for packetized voice? Are these protocol characteristics also suitable for data communications? 4. What testing conditions and testing methods should be recommended to evaluate the performance of the recommended speech packetized system? 5. What method for sending signalling through speech packetization systems should be recommended? 6. What methods for sending digital data, 64 kbit/s clear channel, data modem and facsimile signals through speech packetization systems should be recommended? 7. What methods of signal priority allocation, overload mitigation, speech traffic control and data flow control should be recommended? Points for study 1.Applications and performance requirements that should be considered. 2.Network considerations and restraints, e.g. hybrid combinations of packet and circuit switched speech signals. 3.Packetizing techniques, e.g.: - packet length - synchronization (time stamping) - speech detection - packet assembling - echo control. 4.Implications for network equipment, e.g. packet cross-connect and packet switching systems. 5.The relationship to ATM and broadband ISDN. Notes 1. Account should be taken of the work of Study Group XII on transmission plan issues, and speech performance of digital systems. 2. Account should be taken of the work of Study Group XVIII on the ISDN and general network issues. 3. Account should be taken of the studies of DCME carried out under Question 10/XV. ANNEX 1 (to Question 24/XV) Algorithm and protocol for speech packetization 3. Appendix 1 (to Annex 1 of Question 24/XV) ============================================================ Question 25/XV - Characteristics of monitoring points on digital transmission equipment and systems (New Question) Considering (1) that a new Recommendation on protected monitoring points on digital transmission equipment has been produced during the study period 1985- 1988; (2) some items in the new Recommendation require further study; (3) that monitoring points are an additional means to a Telecommunications Management Network (TMN) for temporarily monitoring the transmitted signal for purposes of fault findings, What revisions and amendments of Recommendation G.772 are necessary? Points for study 1.Completion of Recommendation G.772. 2. Interfaces at the: 2.1 transmission path 2.2 monitor point. 3.Degree of protection from electrostatic discharge and inadvertent application of voltage. 4. Types of measuring instrument to be connected to the monitoring points. 5. Experience with monitoring points. 6. Accessibility of monitoring points - frequency of use. 7. Definition of monitoring point (see Recommendation M.60). Notes 1. Close coordination with Study Group IV will be necessary in the study of this Question. 2. Account should be taken of the study of Operations, Administration and Maintenance interfaces carried out under Question 9/XV. ============================================================ Question 26/XV - Harmonization and update of the texts in Recommendations in Volume III of the Blue Book in so far as they relate to transmission equipment, metallic cables and systems (Continuation of Question 14/XV 1985-88) Considering (1) that there may be inaccuracies in, and inconsistencies between, the texts of Recommendations in Volume III of the Blue Book; (2) that it may desirable to update the text of established Recommendations in Volume III of the Blue Book relating to transmission equipment, metallic cables and systems to take account of important developments, 1. What amendments are required to improve the accuracy and harmonization of the texts of all Recommendations in Volume III of the Blue Book? 2. What amendments are required to update Recommendations in Volume III of the Blue Book insofar as they relate to: 2.1analogue transmission of sound programme and television signals? 2.2 compandors? 2.3 digital multiplex, coding, transcoding and transition equipment? 2.4 metallic cables? 2.5 digital line systems on metallic cables? 2.6 coding and transcoding algorithms? 3. What Recommendations in Volume III of the Blue Book do not need to be reproduced in the next coloured Book? ANNEX 1 (to Question 26/XV) List of remaining items for further studies on Recommendation G.722 1.Section 2: need for separate specifications of the transmission characteristics of the send and receive parts - definition of a "standard transmitter" and a "standard receiver" 2.Point 2.2: the measurement method of the overload point 3.Point 2.4.3: the eventual increase of the group delay specification from 4 to 8 ms in relation with the oversampling techniques for the realization of A/D and D/A converters 4.Point 2.4.6: the signaltototal distortion for the whole codec 5.Points 2.5.5 and 2.5.6: need for a specification of the measurement method of the signaltototal distortion ratio as a function of level and as a function of frequency 6.Point 2.5.8: intermodulation 7.Point 2.6: the eventual specification of the group delay difference between a G.711 implementation and a G.722 implementation in the same terminal 8.Appendix 1 to G.722, Point 1.8: the derivation of a 64 kbit/s PCM signal solely from the lower subband of the 64 kbit/s, 7 kHz signal 9. Appendix 2 to G.722: the test of the QMF ============================================================ Question 27/XV - Terminology for transmission equipment, media and systems (Continuation of Question 27/XV 1985-88) Considering (1) that the continued work on Recommendations often requires new terms and definitions to be established; (2) that it is essential for the work of Study Groups and for liaison with other interested organizations that terms and their definitions be standardized as far as possible, What new terms and definitions relating to transmission equipment, media and systems should be standardized and recommended? (e.g. see annex). Notes 1. Working methods and terms of reference for the study of terminology should be in accordance with Recommendation A.10. 2. Study of this Question requires, in particular, coordination with CCITT Study Groups VI, XI and XVIII. 3. Study of this Question should be coordinated with all other CCI Study Groups via CMV in accordance with Recommendations A.10 and B.13. 4. The study of this Question should be coordinated with the Joint Coordination Group (JCG) of the IEC and CCITT in accordance with Recommendation A.10. In particular collaboration is necessary with: - JCG Working Group C on IEV Chapter 704 "Transmission" -JCG Working Group O on IEV Chapter 731 "Optical Fibre Communication". 5. The publication and presentation of texts on terminology should be in accordance with Recommendations A.14, A.15 and A.16. 6. Recommendation G.701 should be used as the basis for studies of terminology concerning digital matters. Consistency with Recommendation I.112 should be maintained. ANNEX (to Question 27/XV) Terms needing definition ============================================================ Question 28/XV - Characteristics of new multiplexing equipment for the digital hierarchy as given in Recommendation G.702 Considering (1) that there are needs from subscribers and network operators for new facilities and interfaces; (2) that CCITT Recommendations on the G.730, G.740 and G.750-series for PCM, ADPCM and digital multiplexing equipment are well established; (3) that it is likely that new types of multiplexing equipment will be developed which do not come within the scope of these existing Recommendations, nor within the scope of Questions 19/XV and 17/XV, 1. What characteristics should be recommended for new multiplexing equipment which uses low bit rate encoding techniques? 2. What characteristics should be recommended for other types of new multiplexing equipment for the digital hierarchy as given in Recommendation G.702? Points for study 1.Characteristics of transmission interfaces. 2. Maintenance aspects. 3.Applications of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 4.Information and control signals that may need to be passed between multiplexing equipment of this type and a TMN. Notes 1. Study of Operations, Administration and Maintenance interfaces on transmission equipment is carried out under Question 9/XV. 2. Study of this Question should be coordinated with the study of Question 18/XV. 3.Equipment for use in the local network is studied in Question 17/XV. 4. The mapping of 1544 kbit/s signals within a 2048 kbit/s signal is given in Recommendation G.802. However no corresponding equipment has been recommended. ============================================================ Question 29/XV - Characteristics of digital systems on optical fibre cables for the synchronous hierarchy Considering (1) that a number of Recommendations in the G.700-Series gives characteristics on Network Node Interfaces (NNI) and on the synchronous digital hierarchy; (2) that there is a need for new generations of digital systems on optical fibres based on this synchronous hierarchy; (3) that optical fibres may be used for in-station cabling, 1. What new Recommendations should be established regarding digital systems on optical fibre cables based on the new synchronous digital hierarchy? 2. What line interface requirements should be recommended to ensure the transverse compatibility of these systems (i.e. the possibility of mixing various manufacturers' equipment within a single digital line system)? 3. What should be the characteristics of related optical fibre in- station cabling systems? 4. How should other existing Recommendations in the G.900-Series be amended and completed in so far as they relate to systems addressed by this Question? Points for study 1.Systems at bit rate related to the synchronous hierarchy. 2.Attenuation and/or dispersion limited systems. 3.Single-mode fibre systems employing LEDs, multilongitudinal-mode lasers (MLM-LD) and single longitudinal-mode lasers (SLM-LD). 4.Systems not optimized for maximum section length. 5.Wavelength division multiplexing. 6.Systems employing coherent detection. 7.Possible power supply arrangements and related precautions against induced voltages and currents. 8.Environmental conditions. 9.Overall design features. 10.Implications of IEC studies of optical fibre/laser safety considerations. 11.Application of Operations, Administration and Maintenance interfaces as given in Recommendation G.771 - any unique features required. 12.Design methodology - worst case versus statistical design approach. 13.Definitions and test methods of system/equipment parameters. 14.Error performance. 15.Requirements for systems/equipment characteristics which provide transverse compatibility in order to enable equipments designed by different manufacturers to interwork and/or be utilized together in a given digital line system (i.e. the possibility of mixing various manufacturers' equipment within a single digital line system) including optical pulse shape and optical source parameters. 16.The requirements for systems operating on fibres conforming to Recommendations G.651, G.652, G.653 and G.654. 17.The use of optical fibre systems for in-station cabling. 18.Maintenance strategy: 18.1 monitors and alarms, 18.2 supervision and fault location, 18.3 protection switching. Notes 1. Operations, Administration and Maintenance interfaces on transmission equipment are studied under Question 9/XV. 2.Protection switching systems are studied under Questions 5/XV and 6/XV. 3. The study of this Question should be coordinated with the study of Questions 11/XV, 12/XV, 13/XV, 15/XV, 18/XV, 19/XV and 25/XV. 4.Study Group XVIII is responsible for general network issues. 5. Study Group V is responsible for the study of protection against dangers and disturbances of electromagnetic origin. ============================================================ Question 30/XV - Performance characteristics of PCM and ADPCM channels at voice frequencies (Continuation of part of Question 32/XV, studies in 1985-1988) Considering (1) that some specification items in the Recommendations G.712, G.713, G.714 and G.715 need to be completed; (2) that within a widespread digital network, it is envisaged that a telephony connection will ultimately require only a single encoding/decoding process for each direction of transmission; (3) that although Recommendation G.713 gives the requirements for the performance of PCM channels between 2-wire interfaces when used in junction and trunk parts of the network, and another Study Group is defining the performance of digital exchanges between 2-wire analogue interfaces, there is a need to consider the performance of transmission systems used in telephone terminal equipments; (4) that Recommendations in the G- and Q-Series, dealing with the transmission performance requirements for PCM transmission systems and digital exchanges respectively, should, as far as possible, be consistent with each other; (5) that an ADPCM encoding law using 32 kbit/s is recommended in Recommendation G.721, 1. What modifications to existing Recommendations G.712, G.713, G.714 and G.715 should be made? 2. What voice frequency characteristics of equipment using low bit rate encoding, e.g. according to Recommendation G.721, should be recommended? 3. What voice frequency characteristics of equipment for wideband speech coding, according to Recommendation G.722, should be recommended? 4. What are the voice-frequency performance requirements for PCM transmission systems when used in telephone terminal equipment? In particular, what are the transmission performance requirements for PCM encoding/decoding and associated filtering (both in-band and out-of- band) when interfacing directly to or incorporated within a telephone instrument? Points for study 1.Items left under study in the G.710-Series of Recommendations and resolution of discrepancies with respect to the G.550-Series of Recommendations. 2.Recommendations resulting from consideration of parts 2, 3 and 4 of the Question. Notes 1.Study of Point 1 should be coordinated with Study Group XI. 2. Point 2 is also relevant in the context of ISDN terminals. Close collaboration will be required with Study Group XII who are studying certain characteristics of subscribers' apparatus used for telephony. ============================================================ Question 31/XV - Guide for the application of new technologies in local networks Considering (1) that the study of this topic could be of benefit to developing countries; (2) that Study Group XV has already issued two publications on optical fibres; (3) that an important topic with relevant impact on future networks is the application of new technologies in local networks, What studies in cooperation with other Study Groups and GAS are necessary in order to provide guidance to developing countries for the application of new technologies in local networks? Possible items to be considered 1. Introduction strategies. 2.Network architectures, including switching and multiplexing aspects. 3.Accesses and services. 4.Equipment and components. 5.System aspects. 6.Economic and financial aspects. 7.Terminology. Note - This subject is still in an evolutionary stage. The preparation of a publication in the next study period will depend on having gained sufficient practical experience with new technologies in local networks. ANNEX (to Question 31/XV) Optimization of the subscriber network through the introduction of new services and techniques Abstract Due to the vast development of sophisticated and reliable communication systems, most of which are adaptable to the subscriber network, and with regard to the fact that the design of such new techniques will improve the quality of transmission and could solve major problems such as space limitation this is considered to be an appropriate subject for study. Introduction With regard to the fact that subscriber network will utilize the new techniques and services in the near future, we recommend that a study concerning the following facilities and services be undertaken: a) ISDN services; b) digital subscriber multiplexing systems2; c) concentrators1; d) application of ADPCM to double the capacity of 2 048 Mb/s links. In order to implement the above facilities and services more efficiently, the following criteria should be taken into account: 1) the needs of developing countries for the planning of telecommunication networks; 2) with the development of ISDN, many aspects of the traditionally separate voice and non-voice services are likely to be drawn closer together; 3) the need to optimize subscriber network planning. Proposal Due to the widespread application of new techniques in the subscriber network, we propose a study on the following subjects: The study should take into account, from a practical standpoint, planning, maintenance, management (technical and commercial operation), cost and tariff aspects, etc. 1) Recommendation concerning the introduction of subscriber concentrators or digital subscriber multiplexing system (DSMS) for improvement or upgrading the existing subscriber network. 2) Bit rate plan for application of different speed of DSMS on tree networks. 3) Recommendation concerning the application of ADPCM. 4) Recommendation concerning the network planning of the basic ISDN services in a multiplexing mode in existing and expansion cable networks. ============================================================ Question 32/XI - Enhancement and extension of the Q.550-Series of Recommendations on the transmission performance of digital exchanges (New Question) Considering (1) that the Q.550-Series of Recommendations on digital exchanges have been developed over the last three CCITT study periods; (2) that a large number of digital exchanges complying with these Recommendations have already been supplied to administrations and RPOAs; (3) that operational experience in an IDN environment of digital exchanges complying with these Recommendations is rapidly building up, and further considering (4) that many national and international IDNs are already being evolved to become ISDNs; (5) that there is a need to develop these Recommendations in respect of aspects arising from the requirement for digital exchanges to operate in ISDNs, examples of which include: -the impact on digital exchanges of the evolution of the telecommunications management network concept with regard to transmission performance, -the impact on exchange transmission performance design objectives, O&M objectives and measurements of packet mode services, supplementary services etc., -the transmission requirements related to certain ISDN characteristics e.g., to higher quality speech encoding, as well as to spectrum saving low bit rate coding; (6) that there is a need to develop these Recommendations in respect of aspects arising from the requirement for digital exchanges to operate in conjunction with both public land mobile networks and competing fixed land networks; (7) that broadband services will be introduced in ISDNs and may require special interface and other functions within digital exchanges; (8) that digital transmission technology will continue to evolve, possibly at a different rate from exchanges and the latter may be required to support more than one such technology; (9) that connections other than bi-directional circuit switched connections may be required to meet future service requirements, What additions and modifications should be made to the existing Q.550-Series of Recommendations on digital exchanges in order to promote their updating and harmonization with the G.700-Series? In particular the following points should be studied: 1. complete the items listed as "under study" Recommendations Q.551-Q.554; 2. the use of the noise method for the measurements of quantizing distortion and variation of gain with input level; 3. specific transmission requirements applicable to PABXs; 4. requirements for single frequency interference within the voice band; 5.specific transmission requirements applicable to ISDN; 6. conferencing (this point is of interest to Study Groups XII and XV); 7.conditions for establishing speech transmission during call setup; 8.a new Recommendation for exchange transmission measurements; 9.review of attenuation distortion problems; 10. effect of complex impedances and their tolerances, in particular outside the voice band, on broadband measurements, e.g., noise; 11. longitudinal interference threshold measurement techniques; 12. sources and effects of impulsive noise in local digital exchanges; 13. effect of adaptive hybrids on digital exchange transmission requirements; 14. transmission requirements related to higher quality speech encoding; 15. transmission requirements on customer premises equipment necessary to ensure network compatibility; 16. the delay of and the impact of delay on services utilizing multislot connections; 17. means for disabling devices such as 5 /A law converters, echo control devices and digital pads for non speech calls requiring bit integrity. Information concerning some of these points can be found in Annex B.3.7 of COM XI-R 80 (1985-1988). 1 This temporal aspect is for further consideration. 2 It is recognized that certain aspects are being examined by other Study Groups.