1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOM MUN ICATION STANDARDIZATION SECTOR OF ITU G.763 (1 0/98) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital transmission systems - Terminal equipments - Principal characteristics of transcoder and digital mu It i pl cat
2、ion eq u i p me nt Digital circuit multiplication equipment using G.726 ADPCM and digital speech interpolation ITU-T Recommendation G.763 (Previously CCIlT Recommendation) ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONN ECTIONS
3、 AND CIRCUITS INTERNATIONAL ANALOGUE CARRIER SYSTEM GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER- TRANSMISSION SYSTEMS INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE WITH METALLIC LINES COOR
4、DINATION OF RADIOTELEPHONY AND LINE TELEPHONY TESTING EQUIPMENTS TRANSMISSION MEDIA CHARACTERISTICS DIGITAL TRANSMISSION SYSTEMS TERMINAL EQUIPMENTS SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION General Coding of analogue signals by pulse code modulation Coding of analogue signals by
5、 methods other than PCM Principal characteristics of primary multiplex equipment Principal characteristics of second order multiplex equipment Principal characteristics of higher order multiplex equipment Principal characteristics of transcoder and digital multiplication equipment Operations, admini
6、stration and maintenance features of transmission equipment Principal characteristics of multiplexing equipment for the synchronous digital hierarchy Other terminal equipment DIGITAL NETWORKS DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G. 1 OC-G.199 G.200-G.299 G.300-G .399 G .40C-G .449 G .450-G .499
7、G.700-G.799 G.700-G.709 G.710-G.719 G .720-G.729 G.730-G.739 G .740-G .749 G.750-G ,759 G.760-G.769 G .770-G .779 G .780-G .789 G.790-G.799 G .800-G .899 G .900-G .999 For further details, please refer to ITU-T Lisl of Recommendations. ITU-T RECOMMENDATION 6.763 DIGITAL CIRCUIT MULTIPLICATION EQUIPM
8、ENT USING 6.726 ADPCM AND DIGITAL SPEECH INTERPOLATION Summary The revision of this Recommendation is made to harmonize with new Recommendation G.766. This Recommendation is applicable to the design of digital circuit multiplication equipment intended for, but not limited to, use in an international
9、 digital circuit. Freedom is permitted in design details which are not covered in this Recommendation. This Recommendation includes channel check procedure A-Law and p-law test vectors as an electronic attachmen t. It includes also the SDL diagrams for the DCME example of subclause A.3 as an electro
10、nic attachment. Source ITU-T Recommendation G.763 was revised by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1 procedure on the 10th of February 1998. Annex A was further revised by ITU-T Study Group 15 (1997-2000) and was approved under the WTSC Resolution No. 1
11、procedure on the 13th of October 1998. Recommendation G.763 (10/98) i FOREWORD ITU (International Telecommunication Union) is the United Nations Specialized Agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of the ITU. The ITU-T
12、is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for stud
13、y by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1. In some areas of information technology which fall within ITU-Ts purview, the necessa
14、ry standards are prepared on a collaborative basis with IS0 and IEC. NOTE In this Recommendation the term recognized operating agency (ROA) includes any individual, company, corporation or governmental organization that operates a public correspondence service. The terms Administration, ROA and publ
15、ic correspondence are defined in the Constitution of the ITU (Geneva, 1992). INTELLECTUAL PROPERTY RIGHTS The ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. The ITU takes no position conc
16、erning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, the ITU had received notice of intellectual property, protected by p
17、atents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. O ITU 2000 All rights reserved. No part of this publication may be reproduced or
18、 utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. STD-ITU-T RECMN G.b3-ENGL 1498 D 48b259L Obb5325 455 m . CONTENTS 1 General 1.1 Scope . 1.2 Purpose 1.3 . Application 2 Definitions relating to digital c
19、ircuit multiplication equipment (DCME) 3 DCME functions . 3.1 General 3.2 Purpose 4 Operational modes 4.1 General 4.1.1 Point-to-point mode . 4.1.2 Multi-clique mode . 4.1.3 Multi-destination mode 4.1.4 Interoperation . Modes of assignment of channels to the bearer structure . 4.2 4.2.1 Pre-assignme
20、nt . 4.2.2 Dynamic assignment 5 Interface requirements Transmission interface: trunk side 5.1.1 Trunk side interface at 2048 kbit/s 5.1.2 Trunk side interface at 1544 kbit/s Transmission interface: bearer side 5.2.1 Bearer side interface at 2048 kbit/s . 5.2.2 Bearer side interface at 1544 kbit/s .
21、Signalling interfaces to switching equipment (ISC) . 5.3.1 DCME-ISC signalling interface functions 5.3.2 External and internal messageshndications . 5.3.3 Circuit numbering translation 5.3.4 Transmission resource circuit mapping . 5.4 Man-machine interface . 5.5 Operations function interface 5.5,l 5
22、.5.2 Bearer side . 5.6 Local alarms interface . 5.1 5.2 5.3 Trunk side operation at 2048 kbit/s or 1544 kbit/s 5.7 External clock interface Recommendation G.763 (10/98) 1 2 2 2 8 8 8 9 10 10 11 11 12 12 13 13 13 13 13 13 14 14 15 16 16 16 16 16 16 17 17 . 111 5.7.1 5.7.2 DCME working with 2048 kbit/
23、s transmission interfaces DCME working with 1544 kbit/s transmission interfaces 5.8 DCME frame structure 5.8.1 2048 kbit/s structure 5.8.2 1544 kbit/s structure 5.9 BC numbering and use of the bearer frame 5.9.1 5.9.2 5.9.3 5.9.4 5.9.5 5.9.6 5.9.7 Pre-assigned BCs . 8-bit (64 kbit/s) BCs 5-bit (40 k
24、bit/s) BCs Normal range 4-bit BCs . Normal range 4-/3-/2-bit (32/24/16 kbit/s) BCs Overload range 4-/3-bit (32/24 kbit/s) BCs . 3-/2-bit overload procedure . Normal and overload range 3-/2-bit (24/16 kbit/s) BCs resulting from the 6 DCME transmit unit 6.1 Transmit channel processing function 6.1.2 I
25、ntermediate trunk classification . 6.1.3 Input preprocessing 6.1.4 Service request implementation . 6.1.5 Refreshment message generation 6.1.6 ADPCM encoder control . 6.1.7 Bit bank handling and overload channel creation . 6.1.8 Connectivity implementation delay . 6.1.1 DCME transmit unit initializa
26、tion . 6.1.9 Fax bank handling . 7 7.1 DCME receive unit structure Receive channel processing function 7.1.1 DCME receiver unit initialization . 7.1.2 Input pre-processing 7.1.3 Connectivity map update . Bit bank handling and overload channel derivation 7.1.6 Connectivity implementation delay . 7.1.
27、7 TCP and TCH interactions 7.1.8 Fax module interaction . 7 7.1.4 7.1.5 ADPCM decoder connection control 8 8.1 On-demand 64 kbit/s circuit handling connections (transparent circuits) . Action in the case of positive acknowledgement Overview of establishment and disestablishment of 64 kbit/s unrestri
28、cted class 8.1.1 Page 17 17 17 17 17 18 19 19 20 20 21 22 22 23 23 23 23 25 26 28 28 28 33 34 34 34 34 35 35 36 36 36 36 37 37 37 37 iv Recommendation G.763 (10/98) . STDoITU-T RECMN G.7b3-ENGL 1998 = rl8h259L Obb5327 298 W 8.2 Transparent circuit handler (TCH) . 8.2.1 External information elements
29、. 8.2.2 DLC information elements 8.2.3 Other information elements . 8.3 On-demand circuit establishment . 8.3.1 Normal circuit establishment . 8.3.2 Unsuccessful circuit establishment 8.4 On-demand circuit disestablishment . 8.4.1 Normal circuit disestablishment 8.4.2 Unsuccessful circuit disestabli
30、shment . 8.5 Dual seizure handling . 8.5.1 Dual seizure condition . 8.5.2 Dual seizure resolution 8.6 Spurious disconnect handling . 8.6.1 Spurious disconnect conditions . 8.6.2 Spurious disconnect recovery 9 Dynamic load control 9.1 Overview 9.1.1 DLC activatioddeactivation criteria . 9.1.2 Message
31、 processing and routing 9.2 Load condition calculation (see Note) 9.3 Voicehoiceband data DLC . 9.3.1 DCME function . 9.3.2 SCI function . On-demand 64 kbit/s DLC 9.4.1 DCME function . 9.4.2 SCI function . 9.4 10 Test procedures . 10.1 Channel check procedure 10.1.1 Test procedure . 10.1.2 Reporting
32、 test results (remote DCME) 10.1.3 Reporting test results (local DCME) . 10.1.4 Test vector sequence characteristics 10.1.5 Channel check test vectors 10.2 Internal tests 11 Control channel (CC) 11.1 CC error protection . Page 38 39 40 40 40 40 42 43 43 44 45 45 46 47 47 48 49 49 49 50 50 50 50 55 5
33、6 56 56 57 57 57 57 58 58 59 59 60 60 Recommendation G.763 (10/98) V . 7 - . STD-ITU-T RECMN G-7b3-ENGL 3998 48b2591 Obb5328 324 m 11.2 11.3 12 12.1 12.2 12.3 12.4 13 13.1 CC synchronization . 11.2.1 Unique word pattern 11.2.2 Unique word detection . CC message structure 11.3.1 BC identification wor
34、d 11.3.2 IT identification word 1 1.3.3 Data word 11.3.4 CC structure when USM option is used Activity detection and datdspeech discrimination . Transmit activity detector . Threshold and operate time . 12.1.2 Hangover control . Interaction of transmit activity detector with echo control devices Dat
35、aspeech discriminator . 12.2.2 Accuracy 12.2.3 Response time 12.2.4 2100 Hz tone detector Signalling detector 12.3.1 Accuracy Receive activity detector . DCME synchronization 12.1.1 12.1.3 . 12.2.1 Output conditions DCME synchronization and echo control . 13.1.1 Reference clock . 13.1.2 Plesiochrono
36、us slips 13.1.3 Buffer sizes and locations 13.1.4 Terminal synchronization 13.2 Echo control 14 ADPCM encoders and decoders . 15 15.1 Configuration of the DCME for operation in a network 15.2 System management functions . 15.2.1 Transmission facilities . 15.2.2 15.2.3 System statistics measurement O
37、perations and maintenance functions . Terminal traffic handling performance 15.3 Synchronizer . 15.4 Communication links Page 61 61 61 62 62 62 62 65 65 65 66 66 68 68 69 69 69 69 70 70 70 70 70 70 70 70 71 72 72 72 73 74 74 75 75 78 78 vi Recommendation G.763 (10/9S) . STD-ITU-T RECMN G.7b3-ENGL L9
38、98 4862593 0bb5329 Ob0 m 15.5 15.6 15.7 15.8 15.9 15.10 15.11 16 Reports System configuration Failure protection strategy Coordinated traffic rearrangements Voice ordenvire (VOW) . In-service monitonng 15.10.1 Continuous BER measurements 15.10.2 Channel check procedure . 15.10.3 Test port . Fault co
39、nditions and consequent actions 15.1 1.1 Normal traffic carrying operating conditions 15.1 1.2 Fault conditions (see Note) 15.11.3 Explanation of consequent actions 15.11.4 Alarm considerations specific to R2D line signalling . Abbreviations Annex A . Examples of DCME transmitheceive unit structure
40、and SDL diagrams A . 1 An example of a DCh4E transmit unit structure . A . 1.1 Transmit Channel Processing function An example of a DCME receive unit structure . A.2.1 An example of DCME SDL diagrams A.3.1 A.3.2 Logic diagrams for DCME receive side A.3.3 A.2 Receive Channel Processing Function Logic
41、 diagrams for DCME transmit side Logic diagrams for on-demand transparent circuit handling A.3 Appendix I - Additional requirements . I . 1 Load measurements for voice and voiceband data traffic 1.1.1 I . 1.2 Data bearer occupancy determination . 1.2 Transmit activity detector threshold and operate
42、time characteristic . 1.3 Datdspeech discnmnator . 1.3.1 Output conditions 1.3.2 Accuracy 1.3.3 Response time 1.3.4 2100 Hz tone detection 2400 Hz tone detector . Speech detectodecho control device interactions . An example of a DLC double averaging technique for voice traffic . 1.4 1.5 Recommendati
43、on G.763 (10/98) Page 79 79 79 79 80 80 80 84 84 84 84 84 85 86 88 91 91 94 119 122 128 128 142 148 149 149 149 150 150 151 151 152 152 152 152 152 vii 1.6 Timing synchronization 1.6.1 Point-to-point operation . 1.6.2 Multi-clique operation . 1.6.3 Multi-destination operation . 1.7.1 Speech performa
44、nce (provisional) . 1.7.2 Voiceband data performance . Channel check procedure test vectors 1.7 Performance Electronic attachment - A-law - p-law w SDL diagrams for DCME example - DCE-TRANSMIT - DCME-RECEIVE - DCME-TRANSPARENT Page 154 154 159 160 163 163 164 . VI11 Recommendation G.763 (10/98) Intr
45、oduction The rapid growth of facsimile traffic placed severe traffic loading conditions on DCME. In response to this, a new Recommendation G.766 was developed which provides for the introduction of real- time facsimile demodulation/remodulation in DCME. Certain functions required in Recommendation G
46、.766 require additions to this Recommendation, and harmonization is required to align the two Recommendations. The revision of this Recommendation is principally to harmonize it with new Recommendation G.766. In addition, a number of typographical errors in this Recommendation have been corrected an
47、d it has also been updated in accordance with other ITU-T actions. This includes deletion of reference to Recommendation G. 161, which has been declared obsolete. The following modifications were introduced in the 1994 version of this Recommendation: A few technical improvements were made in respons
48、e to operator concerns. One technical issue requiring correction was found in the clause addressing AIS. Investigation of this issue illustrated several ambiguous and confusing aspects of 15.11.2 and 15.11.3, and Table 13 which were then corrected. A modification of the channel assignment refreshmen
49、t procedure was introduced to mitigate freeze- out due to the unavailability of ADPCM decoders in multi-destination applications. A test threshold for the internal channel check for 16 kbit/s overload operation, which had been under study, was introduced in 10.1.4 as well as an expanded channel check test that now includes both A-law and p-law. The optional use of 16 kbit/s ADPCM for overload control has been made a requirement with the inclusion of a selective enableldisable control. The corresponding test vectors are given as electronic files to this Recommendation. A
