1、INTERNATIONAL TELECOMMUNICATION UN ION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Q.56 (05/2001) SERIES Q: SWITCHING AND SIGNALLING International automatic and semi-automatic working - Signalling for circuit multiplication equipment Signalling between signal processing network equipment (
2、SPNE) and international switching centres (ISC) over an IP network ITU-T Recommendation Q.56 (Formerly CCIlT Recommendation) ITU-T Q-SERIES RECOMMENDATIONS SWITCHING AND SIGNALLING SIGNALLING IN THE INTERNATIONAL MANUAL. SERVICE INTERNATIONAL AUTOMATIC AND SEMI-AUTOMATIC WORKING Basic Recommendation
3、s Numbering plan and dialiing procedures in the itertional service Routing plan for intemational service General Recommendations relative to signalling and switching systems (nationai or Tones for use in national signalling systems General characteristics for intemational telephone connections and c
4、ircuits Signalling for satellite systems tiOMl) gnaw uitm on equip FUNCTIONS AND INFORMATION FLOWS FOR SERVICES IN THE ISDN SPECIFICATIONS OF SIGNALLING SYSTEMS No. 4 AND No. 5 SPECIFICATIONS OF SIGNALLING SYSTEM No. 6 SPECIFICATIONS OF SIGNALLING SYSTEM R1 SPECIFICATIONS OF SIGNALLING SYSTEM R2 DIG
5、ITAL EXCHANGES INTERWORKING OF SIGNALLING SYSTEMS SPECIFICATIONS OF SIGNALLING SYSTEM No. 7 43 INTERFACE DIGITAL SUBSCRIBER SIGNALLING SYSTEM No. 1 PUBLIC LAND MOBILE NETWORK INTERWORKING WITH SATELLITE MOBILE SYSTEMS INTELLIGENT NETWORK BROADBAND ISDN CLAUSES APPLICABLE TO ITU-T STANDARD SYSTEMS SI
6、GNALLING REQUIREMENTS AND PROTOCOLS FOR JMT-2000 Q. l-Q.3 Q.4-Q.59 Q.lO-Q.11 Q.12-Q. 19 Q.2O-Q.34 Q.442.9 4.35439 4.40-4.41 4.484.49 4.60-4.99 Q. lOO-Q.119 Q. 120-Q.249 Q.25O-Q.309 4.310-4.399 Q.40O-Q.499 Q.50O-Q.599 Q.60O-Q.699 Q.70O-Q.799 Q.8O-Q.849 43504.999 Q. 100O-Q. 1099 Q. 1 10O-Q. 1 199 4.12
7、004.1699 Q. 170O-Q. 1799 Q.200O-Q.2999 Forjkther details, please refer to the list of ITU-T Recommendations. ITU-T Recommendation 4.56 Signalling between signal processing network equipment (SPNE) and international switching centres (ISC) over an IP network Summary This Recommendation describes a si
8、gnalling interface, procedures, and protocol required between an International Switching Centre (ISC) and Signal Processing Network Equipment (SPNE). This IP-based signalling interface provides for the call-by-call control of an SPNE in real time to ensure an appropriate signal enhancement capabilit
9、y such as echo control. The framework of this signalling interface allows for growth for the control of potential fture SPNE types. Source ITU-T Recommendation 4.56 was prepared by ITU-T Study Group 11 (2001-2004) and approved under the WTSA Resolution 1 procedure on 25 May 2001. Keywords p-Law, A-L
10、aw, Automatic Level Control, Echo Canceller, Frequency Equalization, IP Network, Noise Reduction, Signal Processing Equipment, SPNE. ITU-T Q.56 (092001) 1 FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Tel
11、ecommunication Standardization Sector (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
12、 Assembly (WTSA), which meets every 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 technolog
13、y which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with IS0 and EC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL,
14、 PROPERTY RIGHTS ITU draws attention 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 a
15、sserted by IT members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, U had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned
16、that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. o ITU 2002 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 microfil
17、m, without permission in writing fiom ITU. 11 ITU-T Q.56 (05/2001) CONTENTS 1 2 2.1 2.2 4 5 5.1 5.2 6 6.1 Scope . References . References . Bibliography . Definitions Abbreviations Architecture Network Oriented Architecture Network Protocol Oriented Architecture 5.2.1 Application Protocol Architectu
18、re . 5.2.2 Lower Layer Protocol Architecture . Signalling Procedures . Normal Procedures . 6.1.1 ISC Procedures 6.1.2 SPNE Procedures . 6.2 Abnormal Procedures . 6.2.1 Abnormal ISC Procedures . 6.2.2 Abnormal SPNE Procedures . 6.3 Alarm Handling Procedures 7 Detailed Protocol Descnption . 7.1 Messag
19、e Format Annex A . Lower Layer Protocol Annex B . SDL for SPNE Application . Annex C . SPF Control Information . Appendix I . Channel Monitor (for future study) . ITU-T Q.56 (05/2001) Page 1 1 1 2 2 3 7 7 7 8 8 8 9 10 10 10 14 14 18 19 iii Introduction There is a need in networks for signal processi
20、ng equipment, including echo cancellers, automatic level controllers, frequency equalizers, noise reducers, A-Law to pLaw converters, etc. This equipment needs to be controlled on a call-by-call basis, to ensure the highest possible transmission quality. This Recommendation describes signalling inte
21、rface procedures and a protocol required between an International Switching Centre (ISC) and Signal Processing Network Equipment (SPNE). This signalling interface enables an SPNFi to be controlled in real time, on a call-by-call basis, to ensure the appropriate signal enhancement capability and parm
22、eters are provided for the call. This signalling interface can be used to facilitate the efficient support of existing and future signal processing equipment at the international interface, such as echo cancellers, automatic level controllers, noise reduction devices, frequency equalizers, A-Law to
23、pLaw converters and other capabilities. It can be used to ensure that the appropriate capabilities are enabled or disabled on a call-by-call basis. In this Recommendation, a TCP/IP-based protocol is described which has the ability to address 65 536 ElEl facilities. The method whereby a switch determ
24、ines whether a Signal Processing Function (SPF) should be enabled or disabled is not covered by this Recommendation. iv ITU-T 4.56 (05/2001) ITU-T Recommendation 4.56 Signalling between signal processing network equipment (SPNE) and international switching centres (ISC) over an IP network 1 Scope Th
25、is Recommendation describes a signalling interface between an International Switching Centre (ISC) and Signal Processing Network Equipment, referred to as an SPNE. This Recommendation covers the following SPFs: echo cancellation, noise reduction, automatic level control, A-law/p-law conversion and f
26、requency equalization. Remaining for further study are additional SPF functions, such as PCM offset conversions, etc. The interface is supported over an IP network. This Recommendation is specifically concerned with the transfer of signalling information on a per-call basis between the ISC and the S
27、PNE, and for controlling various functions contained in the SPNE. The signalling interface defined in this Recommendation assumes a fixed relationship between the circuits of the ISC and the SPNE. While this Recommendation is intended for use on international networks, the information defined here m
28、ay be used within national networks. This protocol can support devices that can address channels that occupy less than 8 bits in a PCM slot such as 4,2 and 1 including 8-bit channels. 2 References 2.1 References The following ITU-T Recommendations and other references contain provisions which, throu
29、gh 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; users of this Recommendation are therefore encouraged to investigate the possibility of applying t
30、he most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. 11 ITU-T G. 165 (1993), Echo cancellers. 2 ITU-T G. 168 (2000), Digital network echo cancellers. 3 ITU-T G. 169 (1999), Automatic level control
31、 devices. 4 ITU-T G.703 (1 998), Physical/electrical characteristics of hierarchical digital inte$aces. 5 ITU-T G.704 (1998), Synchronousfiame structures used at 1544, 6312, 2048, 8448 and 44 736 kbit/s hierarchical levels. 6 ITU-T G.711 (1988), Pulse code modulation PCM) of voicefiequencies. 7 ITU-
32、T Q.50 (2001), Signalling between circuit multiplication equipments (Cm) and international switching centres (ISC). SI ITU-T Q.115 (1999), Logic for the control of echo control devices. ITU-T 4-56 (0512001) 1 2.2 Bibliography The documents listed in this clause provide informative background materia
33、l for the reader and are not normative within this Recommendation. 9 101 ITU-T Q.115 (1998), Implementors Guide. IEEE 802 (1990) IEEE Standard for Local and Metropolitan Area Networks: Overview and Architecture. 3 Definitions This Recommendation defines the following terms: 3.1 A-Law - p-Law Convert
34、er (AMC): An A-Law - p-Law converter is a device that converts a PCM signal sample from A-Law to y-Law in one direction, and p-Law to A-Law in the other. 3.2 Automatic Level Controller (ALC): An automatic level controller is defined as an SPF located in the digital transmission path that automatical
35、ly adjusts the level of a signal towards a pre- determined value. Devices that modi the frequency response or spectral content of the signal are also covered by this defition. The telecommunications carrier and the ALC manufacturer will typically agree upon features to be included. See ITU-T G. 169.
36、 3.3 Signal Processing Network Equipment (SPNE): Type of equipment which contains one or more signal enhancement functions on speech channels passing through it. Examples include echo cancellers, noise reduction devices, automatic level controllers, frequency equalizers, A-law to plaw converters and
37、 PCM offset controllers. An SPNE as referred to in this Recommendation is external to an ISC. 3.4 channel: Used herein to refer to a 64 kbits or sub-64 kbits digital circuit occupying a specific position in a frame. 3.5 El Facility: A transmission link operating at 2048 kbits, supporting 30 or 31 64
38、 kbits channels. 3.6 Echo Canceller Device (ECD): An echo canceller device is an SPF that is able to remove some or all of the returned echo signal from a voice circuit. It operates by monitoring the speech signal sent to a voice circuit, and by comparing this signal with the signal received from th
39、e circuit, is able to determine what components of the returned signal are caused by an echo path in the circuit. It then is able to remove some or all of the returned echo, providing a voice circuit that is free or nearly free fi-om the echo signal. ITU-T G. 165 and G. 168 describe echo canceller p
40、erformance. 3.7 Frequency Equalizer (FE): A frequency equalizer is a device capable of amplifjhg or attenuating certain frequencies of a speech channel. It is a subset of an automatic level controller (see above). 3.8 functional entity: A grouping of service providing functions in a single location
41、and a subset of the total set of functions required to provide the service. An entity that comprises a specific set of functions at a given location (from ITU-T Q. 1290). 3.9 group: An assembly, by digital multiplexing, of digital signals occupying a specified number of timeslots to form a composite
42、 signal having a bit rate of 2048 kbit/s or 1544 kbits. 3.10 Incoming Echo Control Device (IECD): An incoming echo control device cancels the echo returned fiom the destination network with reference to the direction in which the call is set up. An IECD is normally located at the destination end of
43、the call. However, it may be located at or near the origination end of the network if its echo processing capability is sufficient to handle the round trip delay from origination end to the destination end and back. 2 ITU-T 4.56 (05/2001) 3.11 Local Area Network (LAN): A shared, 10, 100, 1000 Mbit/s
44、 signalling interface with a transport defined by IEEE and an application component defined in this Recommendation. 3.12 Noise Reduction Device (NRD): A noise reduction device is an SPF that is able to remove some or all of the unwanted noise component from a voice signal. It operates by monitoring
45、the noise and speech signal received from or sent to a voice circuit, and by using a noise reduction algorithm that distinguishes unwanted noise from real speech, is able to remove some or all of the noise signal, providing a voice circuit which is free or nearly free from the noise signal. There is
46、 as yet no ITU-T Recommendation that specifies the performance of a noise reduction device. The telecommunications carrier and the NRD manufacturer will typically agree upon noise reduction features to be included. 3.13 Outgoing Echo Control Device (OECD): An outgoing echo control device cancels the
47、 echo returned from the origination network with reference to the direction in which the call is set up. An OECD is normally located at the origination end of the call. However, it may be located at the destination end of the network if its echo processing capability is sufficient to handle the roun
48、d trip delay from destination end to the origination end and back. 3.14 PCM Offset Controller (for future study): A PCM offset controller is an SPF capable of removing PCM offset from a received A-Law or p-Law voice signal. PCM offset is a constant positive or negative bias contained in the PCM voic
49、e signal, such that a zero analogue input voltage results in a constant, non-zero PCM digital output. 3.15 Protocol Entity (PE): The PE is that part of a layer entity which is dedicated to peer-to-peer communications. A layer PE provides services to the next upper layer and uses services of the next lower layer (refer to ITU-T 4.940). 3.16 3.17 that is contained within an SPNE. An SPNE contains one or more SPFs. 3.18 channel, 2-bit channel, 4-bit channel or an 8-bit channel. 3.19 physical entity: A physical entity contains one or more functional entities.
