1、 International Telecommunication Union ITU-T G.161TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (06/2012) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS International telephone connections and circuits Apparatus associated with long-distance telephone circuitsInteraction as
2、pects of signal processing network equipment Recommendation ITU-T G.161 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 Transmission planning and the E-model G.100G.109 General Recommendations on
3、the transmission quality for an entire international telephone connection G.110G.119 General characteristics of national systems forming part of international connections G.120G.129 General characteristics of the 4-wire chain formed by the international circuits and national extension circuits G.130
4、G.139 General characteristics of the 4-wire chain of international circuits; international transit G.140G.149 General characteristics of international telephone circuits and national extension circuits G.150G.159 Apparatus associated with long-distance telephone circuits G.160G.169Transmission plan
5、aspects of special circuits and connections using the international telephone connection network G.170G.179 Protection and restoration of transmission systems G.180G.189 Software tools for transmission systems G.190G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.2
6、00G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE T
7、ELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRA
8、NSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.161 (06/2012) i Recommendation ITU-T G.161 Intera
9、ction aspects of signal processing network equipment Summary The evolution towards interactive multimedia applications and implementation of new signal processing devices, both in terminals and communication networks, means that a number of sophisticated signal processing algorithms will be deployed
10、 for echo control, noise reduction, level control, voice activity detection, speech coding, speech recognition and voiceband traffic technologies. These technologies may interact with one another and with the imperfections of transmission systems, such as delay and error bursts, to adversely affect
11、the quality of speech and voiceband signals. The purpose of Recommendation ITU-T G.161 is to clarify interaction aspects and to provide guidance to minimize the undesirable interactions of signal processing network equipment (SPNE), between different SPNE, between SPNE and terminals and between SPNE
12、 and transmission systems in telecommunication networks. History Edition Recommendation Approval Study Group 1.0 ITU-T G.161 2002-06-13 15 2.0 ITU-T G.161 2004-06-13 15 3.0 ITU-T G.161 2012-06-29 16 ii Rec. ITU-T G.161 (06/2012) FOREWORD The International Telecommunication Union (ITU) is the United
13、Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendati
14、ons on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization 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 approva
15、l 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, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration
16、“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance
17、with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is requ
18、ired of any party. INTELLECTUAL 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 Intellec
19、tual Property Rights, whether asserted by ITU members or others outside 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. Ho
20、wever, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the
21、prior written permission of ITU. Rec. ITU-T G.161 (06/2012) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 3 3.1 Terms defined elsewhere 3 3.2 Terms defined in this Recommendation . 3 4 Abbreviations and acronyms 7 5 Interaction aspects of signal processing network equipment . 8
22、5.1 Interaction aspects of echo suppressors 8 5.2 Interaction aspects of echo cancellers 9 5.3 Interaction aspects of voice enhancement devices (VEDs) 18 5.4 Interaction aspects of automatic level control 20 5.5 Interaction aspects of circuit multiplication equipment . 21 5.6 Interaction aspects of
23、acoustic echo controllers . 24 5.7 Interaction aspects of voice gateways and IP-based circuit multiplication equipment . 26 5.8 Delay introduced by signal processing network functions . 30 5.9 Some considerations on the preferred locations of voice enhancement SPNE 30 6 Conformance and interoperabil
24、ity 32 Appendix I Tandem-free operation (TFO) 33 I.1 Introduction 33 I.2 Essence of the current standards . 34 Bibliography. 35 Rec. ITU-T G.161 (06/2012) 1 Recommendation ITU-T G.161 Interaction aspects of signal processing network equipment 1 Scope The evolution towards interactive multimedia appl
25、ications and implementation of new signal processing devices, both in terminals and communication networks, means that a number of sophisticated signal processing algorithms will be deployed for echo control, noise reduction, level control, voice activity detection, speech coding, speech recognition
26、 and voiceband traffic technologies. These technologies may interact with one another and with the imperfections of transmission systems, such as delay and error bursts, to adversely affect the quality of speech and voiceband signals. The purpose of this Recommendation is to clarify interaction aspe
27、cts and to provide guidance to minimize the undesirable interactions of signal processing network equipment (SPNE), between different SPNE, between SPNE and terminals and between SPNE and transmission systems in telecommunication networks. 2 References The following ITU-T Recommendations and other r
28、eferences contain provisions which, 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; users of this Recommendation are therefore encouraged to
29、investigate the possibility 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. The reference to a document within this Recommendation does not give it, as a stand-alone document, th
30、e status of a Recommendation. ITU-T G.108 Recommendation ITU-T G.108 (1999), Application of the E-model: A planning guide. ITU-T G.108.2 Recommendation ITU-T G.108.2 (2003), Transmission planning aspects of echo cancellers. ITU-T G.113 Recommendation ITU-T G.113 (2001), Transmission impairments due
31、to speech processing. ITU-T G.131 Recommendation ITU-T G.131 (2003), Talker echo and its control. ITU-T G.164 Recommendation ITU-T G.164 (1988), Echo suppressors. ITU-T G.165 Recommendation ITU-T G.165 (1993), Echo cancellers. ITU-T G.168 Recommendation ITU-T G.168 (2004), Digital network echo cance
32、llers. ITU-T G.169 Recommendation ITU-T G.169 (1999), Automatic level control devices. ITU-T G.177 Recommendation ITU-T G.177 (1999), Transmission planning for voiceband services over hybrid Internet/PSTN connections. ITU-T G.711 Recommendation ITU-T G.711 (1988), Pulse code modulation (PCM) of voic
33、e frequencies. ITU-T G.712 Recommendation ITU-T G.712 (2001), Transmission performance characteristics of pulse code modulation channels. ITU-T G.722 Recommendation ITU-T G.722 (1988), 7 kHz audio-coding within 64 kbit/s. 2 Rec. ITU-T G.161 (06/2012) ITU-T G.722.2 Recommendation ITU-T G.722.2 (2003)
34、, Wideband coding of speech at around 16 kbit/s using Adaptive Multi-Rate Wideband (AMR-WB). ITU-T G.723.1 Recommendation ITU-T G.723.1 (1996), Speech coders: Dual rate speech coder for multimedia communications transmitting at 5.3 and 6.3 kbit/s. ITU-T G.729 Recommendation ITU-T G.729 (1996), Codin
35、g of speech at 8 kbit/s using conjugate-structure algebraic-code-excited linear-prediction (CS-ACELP). ITU-T G.763 Recommendation ITU-T G.763 (1998), Digital circuit multiplication equipment using G.726 ADPCM and digital speech interpolation. ITU-T G.764 Recommendation ITU-T G.764 (1990), Voice pack
36、etization Packetized voice protocols. ITU-T G.765 Recommendation ITU-T G.765 (1992), Packet circuit multiplication equipment. ITU-T G.766 Recommendation ITU-T G.766 (1996), Facsimile demodulation/remodulation for digital circuit multiplication equipment. ITU-T G.767 Recommendation ITU-T G.767 (1998)
37、, Digital circuit multiplication equipment using 16 kbit/s LD-CELP, digital speech interpolation and facsimile demodulation/remodulation. ITU-T G.768 Recommendation ITU-T G.768 (2001), Digital circuit multiplication equipment using 8 kbit/s CS-ACELP. ITU-T G.769 Recommendation ITU-T G.769/Y.1242 (20
38、04), Circuit multiplication equipment optimized for IP-based networks. ITU-T G.799.1 Recommendation ITU-T G.799.1/Y.1451.1 (2004), Functionality and interface specifications for GSTN transport network equipment for interconnecting GSTN and IP networks. ITU-T G.827 Recommendation ITU-T G.827 (2003),
39、Availability performance parameters and objectives for end-to-end international constant bit-rate digital paths. ITU-T G.828 Recommendation ITU-T G.828 (2000), Error performance parameters and objectives for international, constant bit-rate synchronous digital paths. ITU-T P.340 Recommendation ITU-T
40、 P.340 (2000), Transmission characteristics and speech quality parameters of hands-free terminals. ITU-T P.342 Recommendation ITU-T P.342 (2000), Transmission characteristics for telephone band (300-3400 Hz) digital loudspeaking and hands-free telephony terminals. ITU-T P.835 Recommendation ITU-T P.
41、835 (2003), Subjective test methodology for evaluating speech communication systems that include noise suppression algorithms. ITU-T Q.50.1 Recommendation ITU-T Q.50.1 (2001), Signalling between International Switching Centres (ISC) and Digital Circuit Multiplication Equipment (DCME) including the c
42、ontrol of compression/decompression. ITU-T Q.115.1 Recommendation ITU-T Q.115.1 (2002), Logic for the control of echo control devices and functions. ITU-T Q.761 Recommendation ITU-T Q.761 (1999), Signalling System No. 7 ISDN User Part functional description, plus Amendment 1 (2001). Rec. ITU-T G.161
43、 (06/2012) 3 ITU-T Q.764 Recommendation ITU-T Q.764 (1999), Signalling System No. 7 ISDN user part signalling procedures, plus Amendment 1 (2001). ITU-T T.30 Recommendation ITU-T T.30 (2003), Procedures for document facsimile transmission in the general switched telephone network. ITU-T T.38 Recomme
44、ndation ITU-T T.38 (2004), Procedures for real-time Group 3 facsimile communication over IP networks. ITU-T V.17 Recommendation ITU-T V.17 (1991), A 2-wire modem for facsimile applications with rates up to 14 400 bit/s. ITU-T V.18 Recommendation ITU-T V.18 (2000), Operational and interworking requir
45、ements for DCEs operating in the text telephone mode. ITU-T V.21 Recommendation ITU-T V.21 (1988), 300 bits per second duplex modem standardized for use in the general switched telephone network. ITU-T V.23 Recommendation ITU-T V.23 (1988), 600/1200-baud modem standardized for use in the general swi
46、tched telephone network. ITU-T V.26 Recommendation ITU-T V.26 (1988), 2400 bits per second modem standardized for use on 4-wire leased telephone-type circuits. ITU-T V.27 Recommendation ITU-T V.27 ter (1988), 4800/2400 bits per second modem standardized for use in the general switched telephone netw
47、ork. ITU-T V.29 Recommendation ITU-T V.29 (1988), 9600 bits per second modem standardized for use on point-to-point 4-wire leased telephone-type circuits. ITU-T V.32 Recommendation ITU-T V.32 (1993), A family of 2-wire, duplex modems operating at data signalling rates of up to 9600 bit/s for use on
48、the general switched telephone network and on leased telephone-type circuits. ITU-T V.34 Recommendation ITU-T V.34 (1998), A modem operating at data signalling rates of up to 33 600 bit/s for use on the general switched telephone network and on leased point-to-point 2-wire telephone-type circuits. I
49、TU-T V.150.1 Recommendation ITU-T V.150.1 (2003), Modem-over-IP networks: Procedures for the end-to-end connection of V-series DCEs. ITU-R S.1522 Recommendation ITU-R S.1522 (2001), Impact of loss of synchronisation and timing recovery on path availability in hypothetical reference digital paths. 3 Definitions 3.1 Terms defined elsewhere None. 3.2 Terms defined in this Recommendation This Recommendation defines the following terms: 3.2.1 acoustic echo:
