1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T Q.52 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (03/2001) SERIES Q: SWITCHING AND SIGNALLING International automatic and semi-automatic working Signalling for circuit multiplication equipment Signalling between international switching centres and sta
2、nd-alone echo control devices ITU-T Recommendation Q.52 (Formerly CCITT Recommendation) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL SERVICE Q.1Q.3 INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING Q.4Q.59 Basic Recommendations Q.4Q.9 Numbering plan
3、 and dialling procedures in the international service Q.10Q.11 Routing plan for international service Q.12Q.19 General Recommendations relative to signalling and switching systems (national or international) Q.20Q.34 Tones for use in national signalling systems Q.35Q.39 General characteristics for i
4、nternational telephone connections and circuits Q.40Q.47 Signalling for satellite systems Q.48Q.49 Signalling for circuit multiplication equipment Q.50Q.59 FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN Q.60Q.99 CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS Q.100Q.119 SPECIFICATIONS OF SIGN
5、ALLING SYSTEMS No. 4 AND No. 5 Q.120Q.249 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 Q.250Q.309 SPECIFICATIONS OF SIGNALLING SYSTEM R1 Q.310Q.399 SPECIFICATIONS OF SIGNALLING SYSTEM R2 Q.400Q.499 DIGITAL EXCHANGES Q.500Q.599 INTERWORKING OF SIGNALLING SYSTEMS Q.600Q.699 SPECIFICATIONS OF SIGNALLING S
6、YSTEM No. 7 Q.700Q.799 Q3 INTERFACE Q.800Q.849 DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 Q.850Q.999 PUBLIC LAND MOBILE NETWORK Q.1000Q.1099 INTERWORKING WITH SATELLITE MOBILE SYSTEMS Q.1100Q.1199 INTELLIGENT NETWORK Q.1200Q.1699 SIGNALLING REQUIREMENTS AND PROTOCOLS FOR IMT-2000 Q.1700Q.1799 BROADB
7、AND ISDN Q.2000Q.2999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Q.52 (03/2001) i ITU-T Recommendation Q.52 Signalling between international switching centres and stand-alone echo control devices Summary This Recommendation describes a signalling interface between
8、an International Switching Centre (ISC) and an external, stand-alone Echo Control Device (ECD). This signalling interface provides for the call by call control of an ECD in real time to ensure an appropriate speech/signal enhancement capability. Source ITU-T Recommendation Q.52 was prepared by ITU-T
9、 Study Group 11 (2001-2004) and approved under the WTSA Resolution 1 procedure on 1 March 2001. ii ITU-T Q.52 (03/2001) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sect
10、or (ITU-T) is a permanent organ of ITU. ITU-T 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 Assembly (WTSA), which meets every
11、 four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview,
12、 the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws attentio
13、n to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others ou
14、tside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the
15、latest information and are therefore strongly urged to consult the TSB patent database. ITU 2001 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing f
16、rom ITU. ITU-T Q.52 (03/2001) iii CONTENTS Page 1 Scope. 1 2 References. 1 3 Definitions 1 4 Abbreviations 2 5 Requirements/Principles . 2 6 Conceptual Model. 3 7 Network Architecture . 3 7.1 E1-Network. 3 7.2 T1-Network. 3 8 International Switching Centre . 4 9 External Echo Control Device 4 10 ECD
17、 control channel. 4 10.1 E1-Network. 4 10.1.1 Requirements for the control channel equipment 4 10.1.2 Coding . 5 10.2 T1-Network. 5 ITU-T Q.52 (03/2001) 1 ITU-T Recommendation Q.52 Signalling between international switching centres and stand-alone echo control devices 1 Scope This Recommendation des
18、cribes a signalling interface between an International Switching Centre (ISC) and an external, stand-alone Echo Control Device (Echo Suppressor, Echo Canceller), referred to as an ECD. This interface is supported in E1- and T1-networks. The signalling interface defined in this Recommendation assumes
19、 a fixed relationship between the circuits of the ISC and the external ECD. While this Recommendation is intended for use on international networks, the information defined here may be used within national networks. 2 References The following Recommendations and other references contain provisions w
20、hich, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision: all users of this Recommendation are therefore encouraged to investigate the possibilit
21、y of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. 1 ITU-T G.164 (1988), Echo suppressors. 2 ITU-T G.165 (1993), Echo Cancellers. 3 ITU-T G.168 (2000), Digital network echo cancel
22、lers. 4 ITU-T G.704 (1998), Synchronous frame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels. 5 ITU-T G.711 (1988), Pulse code modulation (PCM) of voice frequencies. 6 ITU-T Q.50 (1997), Signalling between circuit multiplication equipments (CME) and international swi
23、tching centres. 7 ITU-T Q.50 Implementors Guide (1998). 8 ITU-T Q.115 (1999), Logic for the control of echo control devices. 9 ITU-T Q.115 Implementors Guide (1998). 10 ITU-T Q.422 (1988), Clauses for exchange line signalling equipment. 2 ITU-T Q.52 (03/2001) 3 Definitions This Recommendation define
24、s the following terms: 3.1 channel associated signalling (CAS): CAS refers to the channel associated signalling referred to in ITU-T G.704 4. 3.2 echo control device (ECD): Type of equipment which is able to remove some or all of the returned echo signal from a circuit carrying voice. Examples for s
25、uch type of equipments are Echo Suppressor and Echo Canceller. 3.3 E1 facility: A transmission link operating at 2048 kbit/s, supporting 30 or 31 64 kbit/s channels. 3.4 T1 facility: A transmission link operating at 1544 kbit/s supporting 24 speech channels. 3.5 external: A device is called external
26、, when it is located outside of the switch. 4 Abbreviations This Recommendation uses the following abbreviations: CAS Channel Associated Signalling CCF Call Control Function DCME Digital Circuit Multiplication Equipment EC Echo Control ECD Echo Control Device ECDCF ECD Control Function ECDSF ECD Swi
27、tching Function ISC International Switching Centre SPD Speech Processing Device 5 Requirements/Principles The control mechanism used between the ISC and the ECD 1, 2, 3 must allow for the use of the ECD on voice circuits controlled by any signalling system, e.g. CCITT R2, CCITT No. 5, TUP and ISUP.
28、The coexistence of the two control mechanisms for ECD (this Recommendation) and Digital Circuit Multiplication Equipment (Annex A or B/Q.50 6, 7) must be guaranteed. ITU-T Q.52 (03/2001) 3 6 Conceptual Model T11112300-01CCFISCECDr1r2Functional PlanePhysical PlaneECDSF ECDSFphysical connection mappin
29、grn relationship between communicating pairs of functional entitiesFigure 1/Q.52 Conceptual methodology model A master slave relation exists between the ECD switching function (located in the switch) and the ECD control function (located in the ECD). 7 Network Architecture 7.1 E1-Network The ECD has
30、 a physical interface according to ITU-T G.704 4 which allows the ECD to be inserted in an E1 transmission facility. The control channel is embedded in time slot 16 (CAS mode: c bit) of the E1 transmission facility. The use of time slot 16 in 2048 kbit/s networks for channel associated signalling is
31、 defined in ITU-T G.704 4. T11112310-01ISC ECDE1ba ECDSFb ECDCFac-bit (time slot 16; CAS)Figure 2/Q.52 External ECD in an E1-Network 4 ITU-T Q.52 (03/2001) 7.2 T1-Network The ECD has a physical interface according to ITU-T G.704 4 which allows the ECD to be inserted in a T1 transmission facility. Th
32、e control channel is physically separated. T11112320-01ECDT1ba ECDSFb ECDCFaT1RS232ISCFigure 3/Q.52 External ECD in a T1-Network 8 International Switching Centre The ISC provides an E1 or T1 circuit interface and a control channel interface. The ISC also provides the logic to decide on a per call ba
33、sis if an ECD is required; ITU-T Q.115 8. The result is conveyed to the ECD via a control channel, see clause 10. 9 External Echo Control Device An external stand alone ECD provides an E1 or T1 circuit interface and a control channel interface. The echo control function can be enabled/disabled for e
34、ach circuit individually. T11112330-01E1/T1 E1/T1Control channelECfunctionECDcontrolfunctionFigure 4/Q.52 External stand alone Echo Control Device ITU-T Q.52 (03/2001) 5 10 ECD control channel 10.1 E1-Network The c bit of time slot 16 (CAS mode) is used to convey the ECD control information from the
35、 ISC to the ECD. 10.1.1 Requirements for the control channel equipment The recognition time for a transition from 0 to 1 or vice versa on the c bit is 20 ms 10 ms. These conditions are the same as those defined in ITU-T Q.422 10. 10.1.2 Coding Either Mode 1 or Mode 2 may be used, as described below.
36、 The selection of which mode is used is implementation dependent. Mode 1: Mode 2: 0 = enable, 1 = disable 0 = disable, 1 = enable 10.2 T1-Network The protocol used to control T1 echo control devices over an RS-232 connection is proprietary and is not standardized. Geneva, 2001 SERIES OF ITU-T RECOMM
37、ENDATIONS Series A Organization of the work of ITU-T Series B Means of expression: definitions, symbols, classification Series C General telecommunication statistics Series D General tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F
38、 Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signal
39、s Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M TMN and network maintenance: international transmission systems, telephone circuits, telegraphy, facsimile and leased circuits Series N Maintenance: in
40、ternational sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Telephone transmission quality, telephone installations, local line networks Series Q Switching and signalling Series R Telegraph transmission Series S Telegraph services terminal
41、 equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks and open system communications Series Y Global information infrastructure and Internet protocol aspects Series Z Languages and general software aspects for telecommunication systems
