1、Technical Report No. 61September 2000Transmission PerformancePlanning Issues Regarding TheIntroduction Of Voice Over ADSLTechnology Into NetworksSupporting Voiceband ServicesPrepared by T1A1.1Working Group onMultimedia CommunicationsCoding and PerformanceProblem Solvers to the Telecommunications Ind
2、ustryCopyright 2000 by Alliance for Telecommunications IndustrySolutionsAll rights reserved.Committee T1 is sponsored by the Alliance for TelecommunicationsIndustry Solutions (ATIS) and accredited by the American NationalStandards Institute (ANSI)No part of this publication may be reproduced in any
3、form,in an electronic retrieval system or otherwise, without theprior written permission of the publisherA Technical Report onTransmission Performance Planning Issues Regarding theIntroduction of Voice over ADSL Technology into NetworksSupporting Voiceband ServicesAbstractThis Committee T1 Technical
4、 Report discusses the transmission performance planningissues associated with the introduction of Voice over ADSL technology into networkssupporting voiceband services. In particular, the Technical Report addresses thetransmission planning issues associated with the Voice over ADSL Integrated Access
5、Device and proposes guidelines associated with its design.Document T1A1.1/2000-013R3Prepared byT1A1.1 Working Group onMultimedia Communications Coding and PerformanceiiThis page intentionally blank.iiiForewordThe implementation of ADSL technology in the network access has provided anopportunity to i
6、ncrease the service support capability of the underlying copper facilities.New technology, referred to as Voice over ADSL Integrated Access Devices (IADs) byindustry, can be used to provide multiple voiceband accesses as a multiplexed serviceover the ADSL system. As these new multiplexed services wi
7、ll use a new class oftechnology, specific industry standards, which provide transmission planning guidanceand hardware design information, are not currently available.This Committee T1 Technical Report was initiated and completed by the T1A1.1Multimedia Communications Coding and Performance in 2000
8、under T1Q1 Project 11.This Technical Report addresses transmission consideration for ADSL IntegratedAccess Devices (IAD) used on customer premises to provide an interface between oneor more customer terminals and an ADSL system. The working group recognized thatthe availability of transmission plann
9、ing considerations and guidelines associated withthe introduction of this new Voice over ADSL would be of benefit to thetelecommunications industry.Suggestions for improvement of the Technical Report are welcome and should be sentto the Alliance for Telecommunications Industry Solutions - Committee
10、T1 Secretariat,1200 G Street N.W., Suite 500, Washington, D.C. 20005.At the time this report was completed, T1A1.1 had the following members:Oscar Avellanada Ralph E. Jensen Ernest SchmidtJohn Boal Barry Lerich Neal SeitzDick Bobilin Doug Lung Henri SuyderhoudEric O. Brockman Alfred C. Morton Leigh
11、ThorpeLorence F. Brown An Nguyen Stephen VoranGregory W. Cermak Ricardo Perez Arthur WebsterDave Curtis Mark Perkins Stephen WolfDavid David Michel Poulin Bernard WorneSuhas S. Gandhi Max J. Roesch Jr. William R. WycoffJohn Grigg John Roquet Wing-Cheong YeungEric G. Hauch Ted Rzcszewski Joe ZebarthR
12、ashid JamalivThis page intentionally blank.vContents1 Scope, Purpose, and Application .11.1 Scope 11.2 Purpose .11.3 Application .12 References.33 Generic Terminology 43.1 Definitions43.2 Abbreviations, Acronyms, and Symbols.54 Architecture 64.1 General64.2 Transmission Considerations.74.2.1 General
13、.74.2.2 Encode Level Characteristic of the Voice over ADSL Codec84.2.3 Decode Level Characteristic of the Voice over ADSL Codec .84.2.4 Delay 94.2.5 Echo Return Loss .94.2.6 Echo .104.2.7 Frequency Response10viThis page intentionally blank.TECHNICAL REPORT NO. 6111 Scope, Purpose, and Application1.1
14、 ScopeThis Technical Report provides transmission planning information and guidelines thatare relevant to the introduction of Voice over ADSL technology into networkssupporting voiceband services. This document views the Voice over ADSL technologyas an alternative access system to the current copper
15、 and subscriber carrier accessloop facilities. Therefore, the discussion is centered on the derived analog service andnot the traditional metallic POTS line. This document supports the principle in T1.508to insert any network loss as near to the end-user terminal as possible and thedesirability of i
16、mplementing any network loss by analog vice digital means.1.2 PurposeThis Technical Report is intended for use by the telecommunications industry tounderstand the transmission planning implications associated with the introduction ofVoice over ADSL technology into networks that support voiceband ser
17、vices. With thisinformation other standards development bodies, manufacturers of Voice over ADSLequipment and network planners and implementors can collectively plan and deploytelecommunications networks that deliver high-quality services to end-users.1.3 ApplicationThis Technical Report applies spe
18、cifically to introduction of Voice over ADSLtechnology into networks supporting voiceband services. The implementationarchitecture assumed by this document is intended to be generic and is not intended torestrict any implementation. The generic, simplified, architecture considered for voiceover ADSL
19、 applications is shown in Figure 1. This simplified figure does not show thePOTS access channel that can be derived on the underlying copper loop facility nordoes it show the multiplexing/demultiplexing of the voiceband channel and other digitaldata on the ADSL system. In general it is assumed that
20、all signals in the digital PSTNcloud are 255, i.e. G.711 encoded signals. A more detailed, but still generic1, derivedPOTS access arrangement using VoADSL IAD equipment is shown in Figure 2.1 The diagram is intended to identify the functions associated with the derivation of a POTSaccess using VoADS
21、L IAD equipment. It is not intended to reflect, recommend, or preclude anyimplementation approach.TECHNICAL REPORT NO. 612Figure 1 Examples of Access and interconnection to the Digital PSTNFigure 2 Example of a VoADSL System with a VoADSL IAD22 Other implementation arrangements are possible and are
22、not precluded.TECHNICAL REPORT NO. 6132 ReferencesThe following documents are resources that may help the readers understanding of thematerial in this Technical Report. At the time of publication, the editions indicated belowwere valid. All standards are subject to revision, and the reader is encour
23、aged to touse the most recent edition of the documents listed below.1. ANSI/TIA/EIA-464-B-1996, Requirements for Private Branch Exchange (PBX)Switching Equipment32. ANSI/TIA/EIA-470-B-1997, Telecommunications Telephone TerminalEquipment Performance and Compatibility Requirements for Telephone Setswi
24、th Loop Signalling3. ANSI/TIA/EIA-810-1999, Transmission Requirements for Narrowband Voiceover IP and Voice over PCM Digital Wireline Telephones4. ANSI/IEEE 743-1995, Standard Equipment Requirements and MeasurementTechniques for Analog Transmission Parameters for Telecommunications5. T1.413-1998, Ne
25、twork and Customer Installation Interfaces - Asymmetric DigitalSubscriber Line (ADSL) Metallic Interface6. T1.508-1998, Network Performance - Loss Plan for Evolving Digital Networks7. T1.508a-2000, Network Performance - Loss Plan for Evolving Digital Networks(Guidelines for Implementation of Local N
26、umber Portability)8. DSLF WT-043, Annex A, Requirements for Voice over DSL Access Facilities toBroadband Loop Emulation Service (BLES), February 20009. ITU-T Recommendation G.114, One-way Transmission Time, February 199610. ITU-T Recommendation G.121, Loudness Ratings (LRs) of National Systems,March
27、 199311. ITU-T G.131, Control of Talker Echo, August 199612. ITU-T Recommendation G.168, Digital Echo Cancelers, April 199713. ITU-T G.176, Planning Guidelines for the Integration of ATM Technology intoNetworks supporting Voiceband Services, April 199714. ITU-T G.711, Pulse Code Modulation (PCM) of
28、Voice Frequencies, November198815. ITU-T Recommendation G.991.1, High bit rate Digital Subscriber Line (HDSL)transceivers, September 199816. ITU-T Recommendation G.992.2, Splitterless asymmetric digital subscriber line(ADSL) transceivers, June 19993 This standard is under revision and its replacemen
29、t ANSI/TIA/EIA 464-C is expected to bepublished in the summer of 2001. Relevant guidance can also be obtained in PN-4819Telecommunications - IP Telephony Gateways IP Telephony Voice Router/Gateway Loss andLevel Plan Guidelines. PN-4819 will be published as ANSI/TIA/EIA/TSB-122.TECHNICAL REPORT NO. 6
30、1417. T1 Technical Report No.59, September 1999, Single-Carrier Rate AdaptiveDigital Subscriber Line (RADSL)18. T1 Technical Report No. 60, July 1999, Unbundled Voicegrade Analog Loops19. Telcordia Generic Requirement GR-303-CORE, Issue 2, 1998, Integrated DigitalLoop Carrier System Generic Requirem
31、ents, Objectives, and Interface20. PN-4819 (to be published as ANSI/TIA/EIA/TSB-122) Telecommunications-IPTelephony Gateways-IP Telephony Voice Router/Gateway Loss and Level PlanGuidelines3 Generic Terminology3.1 DefinitionsThe following definitions apply in this Technical Report3.1.1 access line (l
32、oop): A channel between an end-users network interface and alocal end office or remote switching unit. Note that this definition is slightlydifferent from the loop definition in T1 Technical Report No. 60, which definesthe loop as a channel between the customer/end-user network interface (NI),and a
33、Distributing Frame (DF).3.1.2 analog access line: An access line, with nominal bandwidth of 300 Hz to 3400Hz, composed of analog facilities, digital facilities, or a combination of analogand digital facilities, having an analog or digital interface at the local DEO andan analog interface at the NI,
34、end-user voice terminal, voiceband data terminal,PBX, or interconnecting network.3.1.3 connection: A temporary concatenation of transmission channels ortelecommunication circuits, switching, and other functional units set up toprovide for a transfer of information between two or more points in atele
35、communication network.3.1.4 decode level point (DLP): The decode level point, or d-dB decode level point(d-dB DLP), is a point at which the DRS would be decoded into an analog 1004Hz sinusoid of d dBm.3.1.5 digital access line: An access line composed of digital facilities, containing noanalog secti
36、ons, and having a digital interface at the local DEO and a digitalinterface at the end-user voice terminal, voiceband data terminal, PBX, orinterconnecting network.3.1.6 digital end office (DEO) complex: A complex that includes the DEO and allconnected Remote Switching Units (RSUs), Remote Digital T
37、erminals (RDTs)and Optical Network Units (ONUs).3.1.7 digital loop carrier (DLC): A system that transmits information digitally in thelocal access line and multiplexes multiple channels into a composite signal.3.1.8 digital milliwatt (DMW): The digital milliwatt is a defined digital representation o
38、fa 0-dBm 1000-Hz sine wave applied at the 0 TLP. The digit sequence for a255 representation of the DMW is defined in ITU-T Recommendation G.711.3.1.9 digital reference signal (DRS): A digital representation of a 0-dBm0 1004-Hzanalog sinusoid, such that it will be decoded into an analog signal equal
39、in levelto the analog signal obtained by decoding a digital milliwatt using the samedecoder.TECHNICAL REPORT NO. 6153.1.10 echo return loss (ERL): A frequency-weighted average, over the middle of thevoiceband, of the return losses, RL(f), at any interface in a transmission path,with the transmission
40、 path terminated in a standard impedance at a specifiedpoint. The weighting is given in ANSI/IEEE 743.3.1.11 encode level point (ELP): The encode level point, or e-dB encode level point(e-dB ELP), is a point at which an analog 1004-Hz sinusoid of e dBm would beencoded into a DRS.3.1.12 end-user: The
41、 calling party, or the called party, or both involved with a switchedtelecommunications connection. Customers who use (rather than provide)telecommunication services are end-users.3.1.13 end office (EO): An exchange carrier switching system where access lines(loops) are terminated for purposes of in
42、terconnection to each other and totrunks.3.1.14 network interface (NI): The point of demarcation between the exchangecarriers facilities and the end-user installation that establishes the technicalinterface and may establish division of operational responsibility.3.1.15 transmission level (TL): The
43、transmission level at any point on atransmission system is the ratio in dB of the power of a signal at that point to thepower of the same signal at a reference, i.e. the design loss or gain, expressedin dB, between that point and some other point in the same circuit chosen as areference.3.1.16 trans
44、mission level point (TLP): The transmission level point is a point in atransmission system at which is specified the ratio in dB of the power of a testsignal at that point to the power of the test signal at a reference point. Thereference point, called the zero transmission level point (0 TLP), is a
45、n arbitrarilyestablished point (which may be a hypothetical point unavailable for the actualmeasurement) relative to which transmission levels at all other points arespecified. A signal level of X dBm at the 0 TLP is designated X dBm0.3.1.17 trunk: the channel between switching points.3.1.18 voiceba
46、nd: The set of frequencies between approximately 300 Hz andapproximately 3300 Hz (not necessarily a passband).43.1.19 voicegrade: suitable for transmitting a voice signal.3.2 Abbreviations, Acronyms, and SymbolsADSL asynchronous digital subscriber loop systemDEO digital end officeDLC digital loop ca
47、rrier systemDLP decode level pointDMW digital milliwattDRS digital reference signalEIA Electronics Industry AllianceELP encode level pointEO end officeERL echo return loss4 The frequencies, approximately 300 Hz and approximately 3300 Hz, are based on cables withH88 loading. If another loading scheme
48、 is used, e.g. D66, or if the plant is not loaded, the upperfrequency of the voiceband is constrained by the anti-aliasing filter of the analog-to-digitalconversion process to approximately 3,400 Hz.TECHNICAL REPORT NO. 616Hz HertzIAD integrated access deviceIDLC integrated digital loop carrier syst
49、emITU-T International Telecommunications Union TelecommunicationsStandardization SectorLR loudness ratingNI network interfaceONU optical network unitPBX private branch exchangePCM pulse code modulationPSTN public switched telephone networkRDT remote digital terminalRSU remote switching unitTIA Telecommunications Industry AssociationTLP transmission level pointVoADSL Voice over ADSL4 Architecture4.1 GeneralNetworks intended to support voiceband services are typically accessed by one ormore alternative methods, see Figure 1. Of the possible access arrangements shownin Figure 1, t
