communications standards review · 5/15 compression and classification in signal processing network...

February 23, 2001 Vol. 12.06 Copyright © CSR 2001 1

COMMUNICATIONS STANDARDS

REVIEW

Volume 12, Number 6 February 23, 2001

REPORT OF SG15, WORKING PARTIES 1 AND 2FEBRUARY 5 – 9, 2001, GENEVA, SWITZERLAND

The following report represents the view of the reporterand is not the official, authorized minutes of the meeting.

Report of SG15, Working Parties 1 and 2, February 5 – 9, 2001, Geneva, Switzerland....................3Structure of Study Group 15................................................................................................3SG15 WP1 and WP2 Rapporteurs.......................................................................................3SG15 WP1 and WP2 Editors...............................................................................................4General Matters....................................................................................................................4Future Meetings....................................................................................................................5

Approval of SG15 Documents and Recommendations...............................................................6Documents Approved by the Resolution No. 1 Process.......................................................6Other Documents Approved by Study Group 15..................................................................6Documents Starting the Approval Process............................................................................6Deletion of Supplements.......................................................................................................7

WP1/15, Network Access...........................................................................................................7WP2/15, Network Signal Processing..........................................................................................8Q2/15 WP1, Characteristics of Optical Systems in Local Access Networks...............................8

G.983.dba (A Broadband Optical Access System with Increased Service Capability UsingDynamic Bandwidth Assignment)............................................................................9

G.983.sur (A Broadband Optical Access System with Enhanced Survivability)...................9G.983.wdm (Broadband Optical Access System with Increased Service Capability by

Wavelength Allocation)...........................................................................................10Liaison................................................................................................................................10

Q3/15 WP1, DCEs for Digital Leased Circuits........................................................................11Q4/15 WP1, xDSL Network Access Transceivers....................................................................11

IPR, Intellectual Property Rights.........................................................................................12Liaisons..............................................................................................................................12G.gen (General Issues for all Q4/15 Recommendations Being Progressed).......................14G.989.1, G.pnt (Phoneline Networking Transceivers)........................................................18G.993.1, G.vdsl (Very high speed DSL).............................................................................19G.991.2, G.shdsl (Single-pair High speed DSL transceivers).............................................20G.lite.bis.............................................................................................................................20G.ploam.bis (Physical Layer Operations, Administrations and Maintenance).....................20G.test-bis............................................................................................................................20G.voice................................................................................................................................20G.dmt.bis (Discrete MultiTone)..........................................................................................22G.994.1, G.hs.bis (Hand Shake).........................................................................................22G.995.1, G.ref.bis (Overview).............................................................................................23

COMMUNICATIONS STANDARDS REVIEW

2 Vol. 12.06 Copyright © CSR 2001 February 23, 2001

G.eval ................................................................................................................................23Q5/15 WP2, Management Aspects of Signal Processing Network Elements...........................24

G.768 (8k DCME).............................................................................................................25I.733, VAME......................................................................................................................27IP-CME..............................................................................................................................28

Q6/15 WP2, Circuit Multiplication Equipment and Systems....................................................28Recommendation G.168 (2002), Digital Network Echo Cancelers.....................................28New Voice Enhancement Device (VED) Recommendation.................................................32

Q7/15 WP2, Transport Network Equipment for Interconnecting GSTN and IP Networks......32G.799.1, TIGIN..................................................................................................................32EDH Issues........................................................................................................................34

Q8/15 WP2, Interaction Aspects of Signal Processing Network Equipment............................35Liaisons..............................................................................................................................36

SG15 WP1 & 2 Meeting Roster, February 5 – 9, 2001, Geneva..............................................39Acronym Definitions......................................................................................................................43Communications Standards Review Copyright Policy....................................................................46

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REPORT OF SG15, WORKING PARTIES 1 AND 2FEBRUARY 5 – 9, 2001, GENEVA, SWITZERLAND

This report from SG15 covers the activities of Working Party 1, Network Access, and WorkingParty 2, Network Signal Processing. TD-001(Plen) (P. Wery, Nortel, ITU-T SG15 Chair) containsthe agenda of the SG15 plenary. TD-002(Plen) (P. Wery, Nortel, Chair) summarizes informationrelated to some of the agenda items of the SG15 meeting agenda (TSB Collective Letter 1/15 ofNovember 29, 2000). TD-004R1(Plen) (TSB) lists the SG15 white contributions. TD-005(Plen)(TSB) contains the list of delayed contributions. TD-017(Plen) identifies ITU standardizationareas, domains and their codes.

Structure of Study Group 15

The WTSA appointed the following as the management team for SG15:

Chair: P. Wery, Nortel, CanadaVice-Chairs: G. Bonaventura, Telecom Italia, Italy

H. Okamura, NEC, JapanS. Trowbridge, Lucent Technologies, USA

The WTSA also approved all the Questions proposed by SG15; their texts are contained inCOM15-01. SG15 also remains the Lead Study Group on:

• Optical Technology• Access Network Transport

The following structure for SG15 was agreed:

WorkingParty

Title Qs Chair

1/15 Network Access 2, 3, 4 A. Nunn, BT, UK2/15 Network Signal Processing 5, 6, 7, 8 D. Sparrell, AT&T, USA3/15 OTN Structure 9, 10, 11, 12,

13,14S. Trowbridge, Lucent

Technologies, USA4/15 OTN Technology 15, 16, 17, 18 G. Bonaventura, Telecom Italia,

Italy5/15 Projects and Promotion 1, 19 H. Okamura, NEC, Japan

SG15 WP1 and WP2 Rapporteurs

The following Rapporteurs and Editors for Working Parties 1/15 and 2/15 were approved by StudyGroup 15:

Q Title Rapporteur CompanyWorking Party 1/15

2/15 Optical systems for access networks D. Faulkner BT3/15 Support for Recommendations

Specifying Systems Based on ISDNPhysical Layers

K. Kikushima NTT

4/15 Transceivers for customer access and in-premises phone line networking systemson metallic pairs

R. Stuart 3Com



Working Party 2/155/15 Compression and classification in signal

processing network equipmentY. Naito Mitsubishi Electric

Corporation6/15 Speech enhancement in signal processing

network equipmentB. Reeves BT

7/15 Voice gateway equipment J. Skene Tellabs Oy (FNL)

8/15 Interaction aspects of signal processingnetwork equipment

H. Kullmann Deutsche Telekom

SG15 WP1 and WP2 Editors

Q Rec./Title Editor CompanyWorking Party 1/15

2/15 G.983.wdm (WDM for ATM-PON) T. Sato NTT2/15 G.983.dba (Dynamic Bandwidth Assignment

for ATM-PON)B. Ford BellSouth

2/15 G.983.sur (Extended survivability functions forATM-PON)

H.Ichibangase

Mitsubishi ElectricCorporation

4/15 G.shdsl / G.991.2 (Single pair High bit DigitalSubscriber Line (SHDSL) Transceivers)

S. Blackwell Centillium

4/15 G.dmt / G.992.1 (Asymmetrical DigitalSubscriber Line (ADSL) Transceivers)

F. van derPutten

Alcatel

4/15 G.lite / G.992.2 (Splitterless AsymmetricalDigital Subscriber Line (ADSL) Transceivers)

T. Cole AMD

4/15 G.hs / G.994.1 (Handshake procedures forDigital Subscriber Line (DSL) Transceivers)

L. Brown Conexant

4/15 G.ref / G.995.1 (Overview of Digital SubscriberLine (DSL) Recommendations)

S. Abbas Centillium

4/15 G.test / G.996.1 (Testing procedures for DigitalSubscriber Line (DSL) Transceivers)

M. Tzannes Aware

4/15 G.ploam / G.997.1 (Physical layer managementfor Digital Subscriber Line (DSL) Transceivers)

C. Storry Alcatel

4/15 G.vdsl (Very high bit rate Digital SubscriberLine (VDSL) Transceivers)

S. Palm Broadcom

4/15 G.pnt / G.989.1 (Phone-line NetworkingTransceivers -Foundation)

J. Magill Agere Systems, UK(formerly Lucent –Microelectronics)

4/15 G.voice (Voice over DSL) C. Hansen IntelWorking Party 2/15

5/15 Circuit Multiplication Equipment for IPNetworks (IPCME)

H. Yamada KDD R&D Labs

6/15 G.168 - Digital Echo Cancelers D. Ho Nortel Networks6/15 G.VED - Voice Enhancement Devices N. Dennis Lucent

Technologies, USA

General Matters

TD-001(Gen) (H. Zhao, TSB Director) reports on the results of the WTSA-2000 held in Montreal,Canada, September 27 - October 6, 2000. The main highlights of the Assembly include thefollowing:



• Adoption of new working methods and new tools: a new fast-track approval procedure, knownas the “alternative approval procedure (AAP),” will speed up the adoption of technicalstandards, for example, within two months from the time the text has been declared mature by astudy group.

• Approval of Recommendation D.140 (Accounting rate principles for international telephoneservices), Annex E; this is the famous “transitional arrangement” of target accounting rates tobe achieved by specified deadlines for each country; it will facilitate smooth transition to cost-oriented rates.

• Approval of a new Recommendation on International Internet Connection (RecommendationD.50, formerly known as “D.iii”) setting out the principle of bilateral agreement between twoproviders establishing a circuit carrying Internet traffic between two countries. ThisRecommendation recognizes the possible need for compensation between the two providers.

• The creation of a special study group (SSG) on IMT-2000 and beyond, whose main task willbe to enhance network inter-operability among existing IMT-2000 systems specified by ITU-Rand ITU-T and external standards development organizations (SDOs). This SSG will alsoprovide a migration path regarding network aspects and mobility from existing IMT-2000systems towards systems beyond IMT-2000. WTSA held extensive debate on theestablishment of this SSG, which was given more autonomy and more flexibility in comparisonto other SGs, including the projection of its activities and development of its own workingmethods. This is seen to be a significant step forward toward the objectives of the ITU Reform.

• Delegation of more authority to TSAG (Telecommunication Standardization Advisory Group),including the right to establish or discontinue study groups, to review and to endorse newworking methods, and to oversee external relationships.

• New resolutions on ITU reform and on voluntary contributions to support ITU-T activities.WTSA held extensive discussion of reform-related issues. A summary of the results to theITU Working Group on Reform is attached to TD-001(Gen).

• A strong interest of ITU-T membership in providing chairmanship and vice-chairmanship forSSG and SGs.

TD-002(Gen) (H. Zhao, TSB Director) is the report of the first meeting of the Chairs of the ITU-Tstudy groups for the period 2000 - 2004, which took place in November 2000, in Geneva. The nextmeeting of the ITU-T study group Chairs is scheduled for March 15-16, 2001, in Geneva, just priorto the TSAG meeting March 19-23.

TD-020(Gen) (TSAG Chair) outlines the implementation process for the AAP (alternate approvalprocess, Recommendation A.8). It is expected that the AAP will be used for approval of all futureSG15 Recommendations.

TD-004(Gen) is a liaison from ITU-R SG8 showing the status of questions assigned toRadiocommunication SG8 for the ITU-R study period 2000 - 2002.

Future Meetings

TD-019(Gen) contains the draft schedule of ITU-T meetings for 2001 and beyond. The next fullmeeting of SG15 is scheduled for October 2001 in Geneva, Switzerland. The following interimRapporteur meetings are planned:



Qx/15 Tentative Dates Tentative Place Tentative Host

2/15 June 19-21, 2001 Suffolk, UK BT4/15 April 9-13, 2001 Irvine, CA, USA SBC & Broadcom4/15 May 21-25, 2001 Maine, USA GlobeSpan4/15 August 6-10, 2001 Cairo, Egypt* Compaq5, 6, 7, & 8/15 19-25 April 2001 Japan Mitsubishi Electric

Corp.

*Note: - prior to the meeting an alternative venue/host will be selected if the situation in the MiddleEast is not considered to be acceptable.

Approval of SG15 Documents and Recommendations

Only documents/Recommendations produced by Working Party 1/15 and 2/15 are included below.

Documents Approved by the Resolution No. 1 Process

RECOMMENDATION Documents

G.989.1 – Phoneline Networking Transceivers - Foundation COM15-18 + TD-31(Plen)G.991.2 – Single-pair High-speed Digital Subscriber Line(SHDSL) Transceivers

COM15-3 + TD-11(Plen)+TD-32(Plen)

G.994.1 – Handshake Procedures for Digital Subscriber Line(DSL) Transceivers

COM15-4 (modified) + TD-39(Plen)

G.995.1 – Overview of Digital Subscriber Line (DSL)Recommendations

COM15-20

G.996.1 – Test procedures for Digital Subscriber Line (DSL)Transceivers

COM15-19

Other Documents Approved by Study Group 15

Title Documents

Implementers Guide for G.168 – Digital Network Echo Cancelers TD-43(Plen)

Documents Starting the Approval Process

The following documents received “consent” for approval under the AAP (Recommendation A.8):

Title Documents

G.983.3 (ex G.983.wdm) - A broadband optical access system withincreased service capability by wavelength allocation

TD-40(Plen) + TD-40(Plen)Add1

G.768 - Digital Circuit Multiplication Equipment Using 8 kbit/sCS-ACELP, Digital Speech Interpolation and FacsimileDemodulation/Remodulation.

TD-24 (Plen) + TD-24(Plen)Add1



Deletion of Supplements

TD-024(Gen) (TSB) lists all the old supplements, dated 1988 or earlier, for consideration for SG15deletion. TD-042(Plen) (SG15 Management Team) is the response; it lists the followingSupplements proposed for deletion; they are either technically obsolete or no longer referred to inthe Recommendations indicated:

• G Suppl. 6 (12/1972): Example showing how the total value of line noise specified for thehypothetical reference circuit on open-wire lines might be broken down into its variouscomponents (Referred to in G.223 & G.311)

• G Suppl. 9 (12/1972): Roll effect in coaxial pair systems (Referred to in G.333)• G Suppl. 18 (10/1984): Information on submarine cables used in deep water (Referred to in

G.631)

WP1/15, Network Access

A. Nunn (BT, UK) is the WP1/15 Chair. TD-001(WP1/15) is the agenda of WP1/15 meeting.TD-020(Plen) is the report of this WP1/15 meeting. TD-021(Plen) is the WP1/15 workplan. TD-023(Plen) lists planned WP1/15 interim activities in 2001.

TD-022(Plen) contains the liaisons and communications from WP1/15.

The Questions currently allocated to WP1/15 are:

Q2/15 Optical systems for access networksQ3/15 Support for Recommendations specifying systems based on ISDN physical layersQ4/15 Transceivers for customer access and in-premises phone line networking systems on

metallic pairs

TD-007(Gen) is a communication from WP3/TSAG to inform all ITU-T study groups ofdevelopments regarding EDH. Recommendation A.3 is proposed for deletion at the WTSA.Following the WTSA, the information it contains will be made available as a “Guide for theelaboration and presentation of texts for Recommendations of the ITU-T” at the ITU website.Documents from the 1997 - 2000 study period for all study groups and for TSAG will be archivedby the TSB. Information on how to access these documents will be provided by the TSB.

TD-010(Gen) is a liaison informing that ITU-T SG5 intends to study unbundling andinteroperability problems in relation to EMC, safety, and resistibility aspects. They will study thefollowing subjects:

• For telecommunication systems in use of unbundling cables:– Crosstalk and unbalance requirement of cable– Limit use of subscriber lines in a cable for each telecommunication system– Frequency allocation and frequency band for each transmission system in subscriber cable– Conducted EMC requirement for subscriber interface– Responsibility of each operating company using unbundling cable

• For collocation of all telecommunication equipment installed by different operators in the sametelecommunication center:– Conducted EMC requirements, not only CISPR 22 or 24 band but also below 150 kHz– Requirement for load impedance of equipment power terminal, nominal current, and

transition current limits on power switching when various operators’ equipment isconnected to the same power source.



– Earthing and bonding configuration, lightning current isolation on interface cable, andresponsibility of each operation company

– Safety aspects in multiple operators environments

The next meeting of SG5 is scheduled for June 2001. TD-022(Plen), the response liaison, notesthat spectrum management for subscriber lines will be largely country-specific. There are at leasttwo country-specific spectrum management standards currently in use: T1.417 in the United States,and the OFTEL Access Network Frequency Plan in the United Kingdom.

TD-025(Gen) is a Report and Request from SG4, in its role as lead SG on TMN, to a number ofother ITU-T SGs. SG4 has established a TMN Project Management Team to manage all ITU-TTMN activities. One PMT meeting was held during the SG4 January 2001 meeting. The TMNPMT is responsible for maintaining the TMN Documentation Plan.

TD-028(Gen) presents the new structure of the SG15 informal FTP (iFTP) area.

TD-033(Gen) is a communication from D. Sparrell (AT&T, WP2/15 Chair, SG15 EDHcoordinator) on SG15 EDH coordination activities.

WP2/15, Network Signal Processing

D. Sparrell (AT&T, USA) is the WP2/15 Chair. TD-001(WP2/15) contains the agenda andoutlines the organization of WP2/15 work for this meeting. TD-034(Plen) is the WP2/15 meetingreport. TD-033(Plen) is the document list for the WP2/15 report to the Plenary. TD-035(Plen)(TSB) shows the status of WP2/15 Recommendations. TD-036(Plen) lists and contains theliaisons to/from WP2/15. TD-037(Plen) shows the planned interim WP2/15 meetings.

The Questions currently allocated to WP2/15 are:

Q5/15 Compression and classification in signal processing network equipment (SPNE)Q6/15 Voice enhancement in SPNEQ7/15 Voice gateway equipmentQ8/15 Interaction aspects of SPNE

Q2/15 WP1, Characteristics of Optical Systems in Local AccessNetworks

D. Faulkner (BT, UK) is the Q2/15 Rapporteur. TD-017(WP1/15) is the agenda of the Q2/15sessions at this meeting. The objective of the Q2/15 sessions was to progress draft newRecommendations G.983.dba, Dynamic bandwidth assignment, G.983.sur, Survivability, andG.983.wdm, Wavelength allocation.

Q2/15 agreed that more work is required on the draft Recommendations G.983.dba, and G.983.sur.Completed documents for Consent on these topics will be prepared for the October 2001 meetingof SG15.

It was agreed that enhancements are needed to G.983.1 (Broadband optical access systems basedon passive optical networks [PON]) and G.983.2 (ONT management and control interfacespecification for ATM-PON) on operational, management and control interfaces (OMCI) for anATM-PON. The key benefit sought is enhancing the interoperability of OLTs and ONTs betweenvendors, for example, in the area of frame structures used for circuit emulation.



TD-022(Plen) Annex 3 is the liaison statement to Q16/9 to inform them of the physical layer workin G983.1 and draft G.983.wdm and to ask them to consider using them in at least one possibleimplementation arising from Q16/9 on the transmission of multi-channel analog and/or digitaltelevision signals over optical access networks.

An interim meeting of Q2/15 is planned for June 19-21, 2001 in Suffolk, UK.

TD-016(Gen) (D. Faulkner, BT) is the report of the Q2/15 November 2000 Rapporteurs meeting inPleasanton, California.

G.983.dba (A Broadband Optical Access System with Increased ServiceCapability Using Dynamic Bandwidth Assignment)

TD-022(WP1/15) (B. Ford, BellSouth) is the revised draft Recommendation G.983.dba that wasagreed by Q2/15 at this meeting. It is based on inputs from the white contribution COM15-019and delayed contribution D.46, Proposal for the new draft Recommendation G.983.dba on: “ABroadband Optical Access System with increased service capability using Dynamic BandwidthAssignment” (NTT).

Recommendation G.983.dba describes flexible access networks using optical fiber technologybased on Rec. G.983.1. It describes the functions that extend G.983.1 to enable dynamicbandwidth assignment, and provides the necessary requirements and specifications to enabledynamic bandwidth assignment (DBA) in G.983.1 systems. The requirements and specificationspreserve backward compatibility and interoperability with the current G.983.1 systems, includingmanagement systems. It is anticipated that the introduction of DBA functionality into BPONsystems will increase efficiency and thus lower the cost of providing broadband services. Thefollowing issues will be updated prior to Consent during the October 2001 SG15 meeting:• Mini-slot format to report ONT status• Enhancement of PLOAM message to support multiple T-CONTs in one ONT• Enhancement of transition table for ranging procedures• Handshake procedures• Editorial modifications

G.983.sur (A Broadband Optical Access System with Enhanced Survivability)

TD-024(WP1/15) provides a revised draft Recommendation G.983.sur (v.1.0) that was Agreed atthis meeting. It is based on input from COM15-28, Proposed Draft For A New DraftRecommendation On “A Broadband Optical Access System With Enhanced Survivability”(Rapporteur) and D.43Proposed modifications on draft Recommendation ([COM 15-28]) on “Abroadband optical access system with enhanced survivability” (Mitsubishi, France Telecom). ThisRecommendation describes a flexible optical fiber access network capable of supporting thebandwidth requirements of ISDN and B-ISDN services. It describes systems with nominalsymmetrical line rates of 155.520 Mbit/s and asymmetrical line rates of 155.520 Mbit/s upstream,and 622.080 Mbit/s downstream. It describes the requirements and specifications about protectionfunctions in G.983.1.

The following issues will be updated prior to Consent at the October 2001 SG15 meeting:

• Comparison and selection of protocols• Clear definition of switching layer• Editorial amendments



G.983.wdm (Broadband Optical Access System with Increased ServiceCapability by Wavelength Allocation)

TD-040(Plen) (T. Sato, NTT, Editor) is the final draft of Recommendation G.983.wdm, forConsent at the Plenary. The initial draft (TD-23(WP1/15)) was based on inputs from COM15-27,Proposed Draft For A New Draft Recommendation On “A Broadband Optical Access SystemWith Increased Service Capability By Wavelength Allocation” (Rapporteur), and D.44, Proposedmodifications on draft Recommendation on “Broadband optical access system with increasedservice capability by wavelength allocation” (NTT). The Rapporteur introduced workingdocuments outlining the benefit of further study on telephony and Gigabit PONs; these topics willbe included in future agendas.

Recommendation G.983.wdm describes some extended functions for the ATM-PON systemdefined in Rec. G.983.1. It describes the broadband passive optical network (BPON) system thatuses wavelength division multiplexing techniques (WDM). These WDM techniques allowoperators to provide additional services without disturbing the basic ATM-PON system. Rec.G.983.wdm defines new wavelength allocations to distribute ATM-PON signals and additionalservice signals simultaneously. New wavelength bands for additional services are made available byconstraining the current ATM-PON downstream wavelength to a portion of downstream opticalspectrum originally specified in G.983.1. The new bands have the potential to provideunidirectional and bi-directional services. The wavelength allocation defined in Rec. G.983.wdmenables the distribution of video broadcast services or data services; the Recommendation takes intoaccount the general optical characteristics of these services. The detailed specifications of theseservices, such as modulation scheme, signal format, and so on, are out of scope.

Liaison

TD-008(WP1/15) is a liaison from WP3/SG4 to the ATM Forum (copied to Q2/15 forinformation) regarding the proposed draft Recommendation, “Management services, object models,and implementation ensembles for ATM-PON system,” submitted by the ATM Forum to ITU-TSG4 Q21. In response to a question raised by the ATM Forum, WP3/SG4 responds that it will notbe possible to directly use the ATM-F Network management models in the FSAN APON modelsfor the following two reasons:

• The FSAN consensus was to align APON contributions and to develop the models based onthe ITU-T standards (e.g., M.3100 Amd.) rather than the ATM Forum documents. As a result,the APON contribution developed by FSAN is based on the ITU-T network element andnetwork models.

• FSAN presents the concept of a combined view model, which necessitates the ability to easilynavigate from a network view to a network element view or vice versa. Because both the ITU-Tand the ATM Forum models are specifically targeted to either the network or the networkelement views, it is necessary to specialize particular objects adding additional attributes toreflect this combined view concept. This is why the FSAN model cannot directly use the ITU-Tand the ATM Forum model.

As stated, FSAN based their work on the ITU-T information models, and aligned it with TMNprinciples. In the ATM layers, the FSAN model is aligned to the ATM Forum work. Wherenecessary to demonstrate the concept of the combined view, FSAN has specialized the ATM Forummanaged entities. This specialization is particular to the FSAN work; WP3/SG4 feels that it is notnecessary to propose such changes to the ATM Forum as issues in the ATM Forum models.

Additionally, the FSAN model (ME) is based on the ITU-T models (e.g., M.3100 Amd.) and theATM Forum model for ATM layers. Any discrepancies between the FSAN model and the ATM



Forum model could be because FSAN adopts the ITU-T model as the basis. Therefore, WP3/SG4feels that FSAN should not raise any issues to the ATM Forum and that the ATM Forum shouldliase with the ITU-T to rectify any problematic areas. Finally, WP3/SG4 notes that FSAN feelsthat as the FSAN ATM-PON models are based on ITU-T standards, they should not inhibitinteroperability.

Q3/15 WP1, DCEs for Digital Leased Circuits

K. Kikushima (NTT) is the Q3/15 Chair. The objectives of this meeting were to review and discussthe input documentation to determine the likely future tasks of Q3/15.

From the text of Question 3/15, the following study items were identified:

• Consideration of the necessary refinements and enhancements to the existing B-ISDN user-network interface (UNI) Recommendations (I.432 series)

• Consideration of the necessary refinements and enhancements to the existing B-ISDN servicenode interface (SNI) Recommendations G.967.1, G.967.2 and G.967.3

• Consideration of the necessary refinements and enhancements to the existing B-ISDN servicenode interface (SNI) Recommendations G.964 and G.965

• Revision of Recommendation I.414 (Overview of access Recommendations) as necessary toincorporate VB5 interface, and other recent new Recommendations in the area of access

• Maintenance of the existing ISDN Layer 1 Recommendations I.430, I.431, G.960, G.961,G.962, G.963 (if required)

The following tasks were identified:

• Update I.414 (Overview of Recommendations on Layer 1 for ISDN and B-ISDN customeraccesses) by 2001

• Update I.430 (Basic user-network interface - Layer 1 specification), I.431 (Primary rate user-network interface - Layer 1 specification), I.432 series (B-ISDN user-network interface -Physical layer specification: General characteristics) if required

• Update G.964 (V-Interfaces at the digital local exchange (LE) - V5.1 interface [based on 2048kbit/s] for the support of access network [AN]), G.965 (V-Interfaces at the digital localexchange (LE) - V5.2 interface [based on 2048 kbit/s] for the support of access network [AN])and G.967.x (V-interfaces at the service node [SN]) series by 2001

TD-002(WP1/15) is a liaison from ITU-T SG13 on the status of work transferred to the newQ3/15 from Q11/13 and Q12/13:

• Q11/13, Enhancement and maintenance of ISDN Layer 1: all outstanding work has beencompleted; there are no points remaining in the living list for the Recommendation I.432 series.

• Q12/13, Access network architecture principles and the interface functional characteristics:Recommendations G.964 and G.965 (V5.1 and V5.2 Interfaces) have been revised; theyachieved Consent during the November 2000 SG13 meeting.

Q4/15 WP1, xDSL Network Access Transceivers

D. Stuart (3Com) is the Q4/15 Rapporteur. The scope of Q4/15 is the development ofRecommendations related to digital subscriber line (DSL). TD-016(WP1/15) is the Q4/15 agenda.

TD-004(WP1/15) is the report of the August 2000 Q4/15 Rapporteurs meeting held in Huntsville,Ontario, Canada. TD-005(WP1/15) is the report of the October 2000 Q4/15 Rapporteurs meetingheld in Goa, India. TD-006(WP1/15) is the report of the June 2000 Q4/15 Rapporteurs meeting



held in Antwerp, Belgium. TD-007(WP1/15) is the report of the January 2001 Q4/15 Rapporteursmeeting held in Clearwater, Florida, USA.

IPR, Intellectual Property Rights

25 companies have indicated IPR interest in the G-series Recommendations currently beingprogressed as well as the G.99x.bis Recommendations. The status of providing notification byeither contribution or a letter to the TSB is noted with an X (specific IPR) or G (general IPRstatement) below:

Company IPR1. Adtran X2. Alcatel X3. AMD X4. Broadcom X5. Catena X6. Centillium X

7. Conexant X8. Ericsson9. Globespan X10. Intel X11. Level One X12. Lucent G13. Matsushita G

14. Motorola15. Nortel X16. Paradyne X17. PCTel X18. Sasken X19. Siemens X20. Stanford U.

21. Telia X22. Tioga X23. 3Com G24. TI25. VoCAL X

Lucent has indicated they have made a General IPR Statement to the ITU. Additionally, Ericsson,and Stanford have indicated they expect to make an appropriate ITU Section 2.2 compliantstatement in the future.

Liaisons

TD-003(Gen) is a liaison presenting the Questions assigned to Radiocommunication Study Group9 by the last Radiocommunication Assembly (Istanbul, May 1-5, 2000) for the ITU-R study period2000 - 2002. Of particular note, ITU-R SG9 adopted Question ITU-R 210-1/9, Error performanceobjectives for digital radio-relay sections operating at or above the primary rate of the digitalhierarchy.

TD-009(Gen) is a liaison from SG4 informing that Q15/4 is progressing a new capability on alarmreport control, as M.3100 Amendment 3, Definition of the management interface for a genericAlarm Reporting Control (ARC) Feature (input document D.182, Q4/4). At their last meeting,Q15/4 agreed to the following changes to M.3100 Amd. 3 based on a detailed review of inputsfrom SG15 and T1M1:

The amendment will retain the diagram of the functional model. The fx notation conflictingwith its use for equipment function definitions in G.709 is replaced with the term Fnx. Thisnotation was adopted rather then defining a number of new acronyms only used in conjunctionwith the diagram.

The alarm report control model (M.3100 Amd. 3) will be submitted for Determination at the nextWP4 meeting (August 2001).

TD-015(WP1/15, same as TD-008(Gen)) is a liaison from ITU-D SG2 informing that it hasestablished, in the framework of its Question 12/2 (Examine broadband communications overtraditional copper wires on aspects of technologies, systems, and applications), a Reference Bookon xDSL. It includes a copy of both Chapter 5, The evolution of xDSL, and Annex 3, Trials, forQ4/15 comment and updates. Chapter 5 includes a price/performance analysis of xDSL-basedsolutions vis-à-vis other broadband access solutions which provides a favorable view of ADSL;Annex 3 provides an overview of a few of the many xDSL trials that are currently being conducted.Q12/2 emphasizes that the xDSL handbook should convey experience gained during theapplication of xDSL systems to presumptive users. Q12/2 also acknowledges the possibility that,



due to the various structures and qualities of subscriber loops in different countries, it might bedifficult to use the results from one country for other countries without taking into consideration theparticular subscriber loop parameters. It therefore proposes, as a compromise, to characterizeexisting xDSL installations or test trials according to a simplified description using the followingparameters:

• Type of xDSL system (e.g., ADSL, HDSL)• Typical number of nodes connected to one central office or head-end• Typical data rates (upstream and downstream)• Type of subscriber loop

– Cable type (wire diameter, isolation material)– Cable length– Loop structure (bridged taps)– Noise sources (cross talk, impulse noise, radio interference)

• Cost (provided bandwidth, Internet access)

TD-022(Plen), the liaison from SG15 in response, regrets that SG15 is not able to provide anycomments on the current contents of Chapter 5 as these relate to commercial matters which areoutside the scope of Q4/15. Some of the parameters proposed in the questionnaire relate tocommercially sensitive information and may therefore limit Q12/2’s ability to obtain the requiredinformation from Network Operators. Q4/15 suggests that the DSL Forum may be able to provideuseful information.

TD-027(Gen) (IEC) is the report of IEC Sector Board 4, Infrastructure of telecommunicationsnetworks, after their September 2000 meeting in Stockholm.

TD-023(Gen) contains document SB4/37A/INF from the International ElectrotechnicalCommission (IEC) Sector Board 4, “Flexibility in fixed networks: Cable installation techniques;The example of cable in duct air-blowing.”

In the telecommunications industry, the installation of fixed networks needs particular attentiontoday, because deregulation has forced network installers, and especially telecom operators, tobecome flexible under threat of losing their customers. The very large and expensive investmentrepresented by the fixed network can only keep up with new needs if it can be changed and added-to easily and with minimum costs.

The installation of optical cables in ducts by synergetic pushing and air-blowing is a successfultechnique; it is becoming one of the most widely spread standard techniques now in severalcountries. Not only optical cables are installed with this technique, but also copper cables, e.g.,coaxial or twisted-pair cables. The technique has been improved since it first appeared. Recentresults include:

• 3.5 km of cable blown in with one installation unit• 8 km or 12 km (buffered) of splice-less cable lengths with cascaded units• 32 km cable in one working day• 34 mm cable-diameter with 1.9 kg/m cable-mass blown in over 1 km with one unit and even

over 2 km with cascaded units, making a total of 3.8 tons of cable in “one blow”

SB4/37A/INF reviews this technique and its various appliances, and addresses some currentdevelopments, like the air-blowing of multiple tubes (empty or not) into larger tubes.



G.gen (General Issues for all Q4/15 Recommendations Being Progressed)

The papers discussed under G.gen address multiple Q4/15 projects. The issues discussed belowremain open unless otherwise noted. T. Cole (AMD) is the Editor for G.gen.

D.20 (J. A. Torres, Vocal Technologies) provides details on the power and Euclidean distanceconsiderations with respect to the constellations of G.992.1 and in the case of the non-square QAMconstellations with independent I and Q proposed in CF-038 (F. Hirzel, J. Torres, V. Demjanenko,Vocal Technologies, Clearwater, Florida, January 2001). If all the constellations have the samemaximum power, the Euclidean distance between close points of the constellations proposed in CF-038 is higher than it is with the constellations of G.992.1 and the rectangular constellations. Thisissue remains open.

D.25 (B. Betts, Paradyne) discusses modulated RF ingress testing. G.dmt.bis and G.lite.bisoperate in the frequency range of the commercial AM broadcast band. Each modulated broadcastcarrier is a non-stationary signal spanning a frequency range of 10 kHz. RF ingress will impactthree or four adjacent DMT bins directly, with (sin x)/x coupling to neighboring bins. Correlatednoise in adjacent bins will degrade the performance of the trellis decoder.

A liaison from ETSI TM6 presented at the October 2000 Q4/15 meeting in Goa, India, addressedthe application of modulation to the ingress test signals (BI-032). TD-30r1 (R. Williamson, Nortel,ETSI TM6, Vienna, September 2000) and TS 101 270-1 (Transmission and multiplexing; Accesstransmission systems on metallic access cables; VDSL; Part 1: Functional requirements [ETSITechnical Specification, 1998]) identify suggested modulation requirements. These include amodulation bandwidth of 5 to 6 kHz, which yields a 10 to 12 kHz double side band modulatedsignal. The time varying characteristics of this signal introduce a time varying noise componentinto a single carrier modulation system and bursty, impulsive noise into a multi-carrier system.D.25 recommends that the RF ingress tests use time varying modulated carriers to realize the truedeleterious effect of AM interference.

D.26 (B. Betts, Paradyne) recommends the use of symbol interleaving to mitigate the effects of timevarying modulated AM RF ingress.

D.27 (B. Burke, Voyan) discusses DSL receiver crosstalk compensation using new techniques. Incurrent DSL receivers, channel noise is lumped together and accommodated by reach and raterestrictions as well as margin limits. No attempt is currently made to take advantage of the structureof the interferers. This “single user” approach ignores the underlying sources of noise inenvironments where spectral interference occurs. However, channel capacity is inherently higher incommunications channels that employ “multi-user” receivers to distinguish and address discretenoise sources to affect higher performance (e.g., rates, reach, and margin).

This DSL receiver crosstalk compensation technique takes advantage of such principles tocompensate crosstalk noise and enable higher loop plant utilization. It is configured as a block thatprecedes a standard DMT receiver. The compensator is completely compatible with existing DSLstandards and is designed to be integrated into commercial DSL transceiver chipsets with modestcomputational impact. A receiver technique, the compensation is inherently single-ended and relieson input available in the DSL network. It was tested on simulated DSL disturbers, with asignificant margin gain demonstrated.

D.27 provides examples to illustrate the impact when the compensator is implemented in an ADSLCPE receiver, subject to self-FEXT and foreign NEXT in realistic deployment scenarios. Whereinterference exists due to legacy services, ingress noise, or newly deployed services, a compensatedreceiver will be able to achieve and sustain significantly higher data rates. With the ability of



receivers to reject the effect of interferers, the length limit on potentially interfering services may berelaxed without harm to victim services. Higher rate services will be deployable farther out in theloop plant. Whichever of the available degrees of freedom are used, the loop plant utilization willgrow while preserving spectral compatibility. Since noise sources are identified by the multi-userreceiver, an identification record may be produced by the receiver and sent to the network managerfor use in spectral management. The record can be used to identify noise sources that comply withspectral management rules as well as to uncover noise sources that do not conform.

D.28 (M. Tzannes, Aware) outlines proposals for the new initialization procedure in G.dmt.bis andG.lite.bis. It proposes the following:

• The initialization sequence shall be flexible in length so that training can be optionallycompleted in 1-2 seconds. The receivers shall control the duration of the initialization states.

• The PARAMETERS message shall allow the receiver to optionally send either the entire Bi/Gitable or a profile number.

• The initialization sequence shall contain a line probe state for the ATU-C.• The initialization sequence shall provide power cutback capability initiated by the ATU-C.• 8 bit per DMT symbol encoding shall be accomplished using 256 QAM on all the subcarriers.

D.31 (J. Carlo, B. Wiseman, Texas Instruments) proposes that the G.dmt.bis and G.lite.bisstandards agree to mandatory and optional maximum parameters for framing. Specifically, itproposes the following:

• Maximum mandatory number of bearer channels (NBC) shall be one• Maximum number of optional bearer channels shall be four• Maximum mandatory number of latency paths (NLP) shall be one• Maximum number of optional latency paths shall be four• Interleaver memory mandatory on only one latency path, which is labeled (NLP-1), the highest

numbered latency path (This was not agreed: there was some concern that it would be better toput the interleaved path on the lowest interleave channel.)

• Maximum mandatory interleaver depth shall be 2n where n = 0, 1, 2, 3 for upstream, and n = 0,1, 2, 3, 4, 5, 6 for downstream

• Maximum mandatory number of bits per tone shall be 15• Mandatory FEC redundancy values shall be 0, 2, 4, 8, 16• Mandatory Mp values shall be 1, 2, 4, 8, and 16

D.32 (J. Carlo, B. Wiseman, F. Chow, K. Kratochwil, Texas Instruments) proposes a framingscheme for the overhead channel for next generation ADSL modems. Two proposals for theframing of the overhead channel were presented at the October 2000 Q4/15 Rapporteurs meeting inGoa, India. The first (BI-094, F. Van der Putten, Alcatel) uses one sync byte per mux data frame(MDF) to carry the overhead channel. The second (BI-048, ADC Telecommunications, Aware,Cisco, Ikanos, Legerity, Siemens ICN, SigmaTel, Texas Instruments) moves the overhead channelinto a separate latency path; it thus achieves a separation of the frame overhead data rate from thenet data rates in all latency paths. That is, changing any net data rate will not affect the frameoverhead rate as long as LOH (i.e., the number of overhead bits per DMT symbol) is kept constant.D.32 compares these two proposals, points out the issues of each, and suggests a slightly modifiedframing scheme that combines the advantages of each while avoiding their disadvantages.

By setting the parameter Tp = 1, the resulting framing of the overhead channel is identical to havingone sync byte per mux data frame as suggested in BI-094. On the other hand, by setting theparameter NBC,p=0 for one latency path, the separate overhead channel suggested by BI-048 isobtained. This proposed framing scheme decouples the overhead bytes from the mux data frame; itthus achieves that no frame overhead rate is wasted on latency paths that carry only CRC and path-related indicator bits in the overhead channel. This proposed framing scheme satisfies all the



requirements outlined in BI-106 (T. Cole, AMD, Ad hoc Convenor), the report of the ad hoc onframing and overhead structure and protocol.

D.33 (M. Sorbara, GlobeSpan) discusses timing requirements for bit synchronous channel inADSL. The current issue of G.992.1, ADSL Transceivers, defines a framing mode of STMtransport and a separate mode for ATM transport. There is agreement to define a dual bearer modefor simultaneous transport of STM and ATM channels for both G.dmt.bis and G.lite.bis.Definition of the dual bearer operation is being driven by the activity for G.voice. D.33recommends that the following timing configuration options be considered for G.dmt.bis andG.lite.bis relative to the support of bit synchronous payloads:

• Configuration 1: Synchronize the ADSL line clock with the STM payload clock or NTR• Configuration 2: Define a stuffing mechanism in sub-channel frame (or bearer) for transport of

the STM channel

D.34 (M. Sorbara, GlobeSpan) proposes a framing structure (TPS-TC) for G.dmt.bis andG.lite.bis for the transport of PCM Voice and CCS/CAS signaling in the physical layer. As withany bit synchronous payload, a requirement for the transport of Nx64 kbit/s PCM voice is to passthe network timing reference end-to-end. To address the synchronization issue, this frame structureincludes a stuff/delete mechanism to pass the payload’s timing reference end-to-end on the ADSLlink. Although this structure is driven by the requirements of G.voice, this structure is easilyextended to any bit-synchronous payload.

D.86 (P. Reusens, D. Van Bruyssel, Alcatel Bell) discusses a proposal to make tone ordering morerobust, to help the receiver defend itself more effectively against intermittent narrow frequencyinterference. In D.634 (P. Reusens, Alcatel, SG15, Geneva, 1999), four new study points wereadded to the issues lists for the enhancement of the DMT modulation of G.dmt.bis and G.lite.bis.Of these, issue 5.1 of G.dmt.bis proposed that in G.dmt.bis the receiver shall specify the toneordering, transmitted with an (i, bi, gi) message; this has not yet been handled. D.86 shows thatsuch RFI is often caused by the varying levels of the modulation of AM stations. In the presentG.lite and G.dmt, the sequential bits are put on adjacent carriers; this can be improved when Trelliscoding is used. Therefore, D.86 proposes that the “frequency ordering” of DMT carriers not besequential in G.gen.bis. Furthermore, it proposes, the frequency order should be under control ofthe receiver, and the transmitter should have a mandatory capability to deliver the order requested bythe receiver. The ability of flexible reordering should be negotiated during G.hs and exchanged asan improved (i, bi, gi) list during the same message currently containing the (bi, gi) list. D.86proposes that item 5.1 be decided, and that the following new agreed item be added to the issues list(under improved coding techniques): study the effect of the narrow banded and modulated AMsignals of non-stationary nature on the error correcting capability of all proposals for improvedcoding gain. (Similar actions are needed for the issues list of G.lite.bis.)

D.87 (P. Reusens, D. Van Bruyssel, Alcatel Bell) analyses the semi-stationary Q-signal proposedin the following documents:

• BA-045 (Orckit Communications) documented the advantages of a semi-stationary Q-modesignal.

• HC-029R1 (Orckit Communications) presented a specific proposal for a semi-stationary Q-mode signal. That proposal included a pair of PRBS generators, each with a period greater than4000.

• BI-080 (J. Carlo, M. Locke, Texas Instruments) proposed that the “non-stationary” signal inQ-mode consist of vendor-specific 4QAM modulation on the applicable tones forREVERB/SEGUE rather than the specific PRD (pseudo-random downstream) sequence.

• CF-033 (R. Verbin, Tioga Technologies) discussed a semi-stationary Q-mode signal.



D.87 agrees that the REVERB signal is a good starting point to derive the “filler” signal (BA-045,HC-029R1), but rather than using REVERB with a distortion (as proposed in CF-033), the crestreduction might be advantageously achieved by altering the bit content of the original REVERBsignal, which would be in line with BI-080. As the optimization of the signal is most important tothe transmitter, the actual bit pattern should defined by the transmitter, also as in BI-080. Therelated bit content of the 4QAM filler symbols should be communicated to the receiver via amessage (64 bytes). The receiver should have a mandatory capability to accept any bit pattern ofthe filler signal. The actual content derivation should not be standardized, but could, for example, bederived at the transmitter from the original REVERB by iterations similar to one proposed in CF-033.

At the Q4/15 January meeting in Clearwater, Florida, Issue 13.3.11 of the G.dmt issues list wasagreed: the Q-mode proposal shall define a TBD tolerance for the REVERB signal, in the definitionof the semi-stationary Q-mode signal, to allow a vendor-discretionary optimization of the Q-modesignal to the vendor-specific transmit path. D.87 proposes that, in defining the tolerance, marked asTBD, the word REVERB not be interpreted to be the same as the older REVERB of the G.dmtinitialization sequence. Instead, it should be newly defined as a filler signal for G.dmt.bis, possiblybased on the older G.dmt signal but being a more generalized 4QAM signal specified by thetransmitter. This would make it more in line with BI-080, and different in bit-content from the olderREVERB definition.

TD-021(WP1/15) (A. Carlson, Broadcom, Ad hoc Convenor) is the report of the ad hoc which metto discuss past contributions pertaining to Q-mode. The Convenor prepared background notes(attached as Appendix A to TD-021(WP1/15)) to support discussion intended to find a basis fornarrowing the range of Q-Mode proposals. The ad hoc agreed to the following two proposals forconsideration by Q4/15:

• The Q-mode proposal shall include a means by which the ATU-x receiver can maintaintransceiver tracking during Q-mode.

• Q-mode shall not be a full-duplex concept and shall not be negotiated between transmitter andreceiver.

Appendix A lists:

• Existing Q-mode agreements• Either/or Q-mode issues• Q-mode signal proposals• Requirements referenced in Item 13.2.6 of the G.dmt.bis issues list (CF-U17R2) as extracted

from CF-040 (P. Reusens, D. Van Bruyssel, Alcatel; R. Verbin, Tioga Technologies),including:– General requirements– Specific requirements for ATM TPS-TC application option– Specific requirements for PMS-TC and PMD

• Contributions addressing the subject of Q-mode

D.88 (P. Reusens, Alcatel Bell) discusses some material presented in PO-038R1 (F. Van derPutten, P. Reusens, R. Cassiers, Alcatel, Q4/15 Sunriver, Oregon, January 1999), which firstproposed the new quiescent mode, and CF-040 (P. Reusens, D. Van Bruyssel, Alcatel; R. Verbin,Tioga Technologies), which repeated the high-level characteristics of the Q-mode proposal as firstproposed in PO-038. D.88 proposes at least one new item for agreement (if it is not alreadydefined), which is also proposed in CF-040: definition of a synchronous scrambler which takes theunscrambled data of the TC layer and scrambles those bit sequences with an EXOR with identicalpseudo-random bit streams, generated in synchronization in the PMD layers of the transmitter andthe receiver.



D.91 (I. Sharfer, Tioga Technologies) proposes a definition of spectrum shaping parameterssupporting operation with a notched transmit PSD. At the Q4/15 January 2001 Clearwater meeting,CF-034 (I. Sharfer, Tioga Technologies) proposed a mechanism to exchange spectrum shapinginformation between ATU-C and ATU-R. At that meeting, Q4/15 agreed that this exchange willtake place during the initialization. Following the meeting discussion and subsequent off-linecomments, this proposal was shown to contain several deficiencies related to the interpretation ofthe spectrum shaping parameters as cutback levels applied to the transmit PSD. D.91 amends theseidentified deficiencies; it also extends the proposed definition to the fast retrain sequence of G.lite.

TD-028(WP1/15) (S. Abbas, Centillium, Ad hoc Convenor) is the report of the ad hoc onmandatory latency paths. Based on a prior agreement to optionally support up to four latencypaths, the ad hoc agreed to not support three or four mandatory latency paths. The main issue ofthe meeting then became whether to support one or two mandatory latency paths. It was agreed toleave open the question of whether to support two mandatory latency paths, to be decided in thenext meeting. It was agreed that, obviously, the support of at least one mandatory latency path isnecessary to pass data through the modem. Specifically, the ad hoc agreed to the followingstatement regarding one latency path:

• There shall be one mandatory latency path for transmitting and receiving the mandatoryminimum one bearer channel.

G.989.1, G.pnt (Phoneline Networking Transceivers)

TD-009(WP1/15) (J. Magill, Agere Systems, Editor) is the updated issues list for the G.pntRecommendations; it includes the agreements from the G.pnt sessions held during the Q4/15January 2001 meeting in Clearwater, Florida.

COM15-18-E (J. Magill, Lucent, Editor) contains the text for draft new ITU-T RecommendationG.989.1, Phoneline networking transceivers – Foundation (formerly G.pnt.f), for Approval. ThisRecommendation specifies the basic characteristics of devices designed for the transmission of dataover in-premises phoneline networks. Additionally, it provides for spectrum notching forcompatibility with amateur radio services. It defines:

• The system reference model for these devices• The PSD mask• The line signal frame format• The media access protocol• Basic electrical characteristics

TD-031(Plen) (J. Magill, Agere, Editor) contains all the proposed changes to draftRecommendation G.989.1 (COM15-18) following Q4/15 discussion during this meeting; itreplaces TD-014(Plen).

TD-018(Plen) (J. Magill, Agere, Editor) provides background information on the current text indraft Rec. G.989.1 regarding the use of isolation filters with phoneline networking transceivers.The use of isolation filters in conjunction with PNT devices has been discussed since the beginningof the work on PNT Recommendations. The current text on the use of isolation filters in draft Rec.G.989.1 was agreed at the SG15 meeting in Geneva in April 2000, prior to Determination of theRecommendation. Lengthy discussion of the issues surrounding the use of isolation filters led tothe conclusion and agreement that it was not appropriate to mandate use of isolation filters, but thattheir use should be strongly encouraged, in accord with the current text. Although a project for



isolation filters (G.pnt.if) was formally opened in June 2000 with a number of potential study items,no contributions on requirements have been previously received.

D.03 (S. Cascelli, Ministero delle Comunicazioni (ISCTI), Rome, Italy) discusses the proposedoptional isolation filter in the draft new Recommendation G.pnt.f (G.989.1). Rec. G.989.1 containsa reference to an “optional isolation filter” (also inserted in the basic reference model) which is“strongly encouraged to provide spectral isolation with wide area network access technologies, e.g.,VDSL.” The issues list for G.pnt (BI-U12) contains a section including ten open items dedicatedto the specification of this optional isolation filter, which will create a new Recommendation namedG.pnt.if. The issues list for G.pnt also contains many open issues concerning VDSL and PNTinterference. Italy asserts that Q4/15 has not fully investigated the issue related to the compatibilityof G.pnt with VDSL and what the characteristics of the isolation filter should be. If G.pnt.f ispublished as is, G.pnt equipment can be standard compliant without the isolation filter. This couldcause interference into any operator’s access network. The procedure to detect the source of theinterference will be extremely difficult and costly for operators. Moreover, the cost of thisprocedure would constitute a de facto penalty for customers using PNT in their own in-premisesphoneline networks without even being aware of the potential interference of PNT into accessnetworks.

Italy concludes that without the “isolation filter,” a strong probability exists that disturbances toother network access technologies ( e.g., VDSL ) will be caused. Consequently, Italy proposes thatApproval of the Recommendation G.pnt.f as it stands be postponed, unless the use of the isolationfilter is made mandatory instead of optional.

TD-020(WP1/15) (J. Magill, Agere Systems, Editor) contains the changes to COM15-18,proposed by an ad-hoc editing group, and resulting from the discussions of D.03. Some of theagreed changes include:

• Add the following definition to Section 2: “Isolation function – a device which providesspectral isolation between the in-premises wiring and the access network, such as a filter,gateway, etc.”

• In Section 3, change the definition of “IF” to read “isolation function”• Change the last sentence of the first paragraph of Section 4 from “An optional isolation filter

(IF) separates the in-premises wiring from the access network” to “An isolation function (IF)separates the in-premises wiring from the access network.”

• Add the following text to Section 4, following Figure 4/G.989.1: An isolation function (IF)shall be implemented when necessary to prevent interference between PNT devices operating onin-premises wiring and access network technologies that use an overlapping frequencyspectrum e.g., VDSL.

• Additionally, Figure 1/G.989.1, Basic reference model, and Figure 4/G.989.1, Networktopology examples, were replaced with new figures.

G.993.1, G.vdsl (Very high speed DSL)

TD-013(WP1/15) (S. Palm, Broadcom Home Networking, Editor) is the updated issues list forG.vdsl as of February 1, 2001. There were no contributions on VDSL directly. The onlycontributions indirectly related to VDSL were on code points in G.hs for the regional VDSL specs,and these were handled in the HS discussions. This led to the codepoints defined in the approvedversion of G.hs-bis (G.994.1, TD-39(Plen)), and “communications” to ETSI and T1E1 (see TD-22(Plen) Annex 4).



G.991.2, G.shdsl (Single-pair High speed DSL transceivers)

COM15-3-E is the new draft Recommendation G.991.2, Single-pair high-speed digital subscriberline (G.shdsl) transceivers, for Approval.

TD-011(Plen) (S. Blackwell, Centillium, Editor) contains a list of agreed changes to draftRecommendation G.991.2 (COM15-3). TD-032(Plen) (S. Blackwell, Centillium) lists furtheramendments to COM15-3.

TD-003(WP1/15) (S. Blackwell, Adtran, Editor) provides the input as required byRecommendation A.5 for the IETF reference in §9.5.5 of draft Recommendation G.991.2 (exG.shdsl) for Approval.

G.lite.bis

TD-014(WP1/15) (T. Cole, AMD, Editor) provides the issues list for G.lite.bis based oncontributions, discussion, and agreements as of January 12, 2001, the close of the Clearwatermeeting.

TD-019(WP1/15) (T. Cole, AMD, Editor) is the G.lite.bis draft Recommendation.

TD-018(WP1/15) (T. Cole, AMD, Editor) is the G.lite.bis work program; it is based oncontributions uploaded and presented as of February 5, 2001, the opening day of this meeting.

G.ploam.bis (Physical Layer Operations, Administrations and Maintenance)

No activity was reported at this meeting.

G.test-bis

TD-025(WP1/15) (M. Tzannes, Aware, Editor) is the issues list for G.test; it includes issues for thenext version of G.test. See also the G.eval report, below.

G.voice

TD-027(WP1/15) (C. Hansen, Intel, Editor) is the G.voice updated issues list.

D.29 (S. Abbas, Centillium; B. Wiseman, Texas Instruments; R. Kroninger, ADCTelecommunications, Ikanos) discusses potential mechanisms to transport channelized voicesignaling and data across the ADSL STM-TC. The ADSL STM-TC performs cross-layercommunications by passing primitives with certain parameters to the layers above and below.ADSL STM-TC configuration for channelized voice should accommodate transport of bothsignaling and voice data. D.29 describes the following two potential mechanisms to transportchannelized voice signaling and data across the ADSL STM-TC:

In the first approach, each ADSL PMS-TC frame transports two bytes of data per active PCMchannel (i.e., 64 kbit/s) and one byte of signaling information using two bearers. If there are NPCM byte streams P(i,j), i=1..N (N<=8), and j is the sample index, then the data bytes are orderedas C(i+N*j), as shown in Figure 1. The bytes are transported from left to right.



PCM channels byte order (N active channels - 2N bytes)

PCM 1 PCM 2 PCM N PCM 1 PCM 2 PCM N

0.25 ms

Figure 1, D.29

One STM-TC bearer with N*64 kbit/s bandwidth carries the PCM frame. Another STM-TCbearer is used to carry the signaling information configured for the minimum bandwidth of 32kbit/s.

In the second approach, both PCM samples and signaling information can be carried on one STM-TC bearer by multiplexing the PCM sample bytes and signaling byte. Figure 2 shows a suitablemultiplexing scheme.

SIGPCM 1 PCM 2 PCM N PCM 1 PCM 2 PCM N

PCM channels and signaling byte order (N active channels - 2N+1 bytes)

0.25 ms

Figure 2, D.29

In this approach, the bandwidth requirement for the STM-TC bearer would be (2N+1)*32 kbit/s.D.29 recommends this second approach. This issue was opened on the issues list.

D.30 (S. Abbas, Centillium; B. Wiseman, Texas Instruments; R. Kroninger, ADCTelecommunications, Ikanos) discusses an out-of-band mechanism to transport either CAS or CCSsignaling messages across an ADSL link for channelized voice. Two techniques are commonlyemployed for telephony signaling: state-based (CAS) and message-based (CCS) signaling. Thesignaling information can be carried across a physical layer in-band or out-of-band. In-bandsignaling uses overhead in the same path as the voice data to transport the telephony signalinginformation; out-of-band signaling uses messages that communicate the telephony signalinginformation in a path that is not the same as voice data. Out-of-band signaling may use anexclusive path or a path shared by other control and management functions across the physicallayer. It has been agreed that G.voice shall optionally support the transport of both CCS and CASsignaling messages across the U interface. D.30 proposes an HDLC-based frame structure to beused to encapsulate both CAS and CCS signaling messages associated with channelized voice. Useof HDLC frame provides CRC, multiplexing, and variable length framing benefits. This methodmay also be used to transport either CAS or CCS signaling messages across other DSL links forchannelized voice. It was agreed to include the text in Section 2 of D.30, which defines the CCSand CAS signaling, in Section 0 of G.voice.

D.35 (C. Hansen, Intel) proposes a document content for G.voice to describe one way in whichG.voice may be written to document the necessary voice features in support of VoDSL. The basicdocument structure it presents describes a G.voice Recommendation that is “placed”architecturally between an xDSL Recommendation and the telephony voice terminals. For thepurposes of a document structure, and taking into account the structure of the current ADSL.bisdraft text, the G.voice Recommendation could be organized into three main sections:

• A reference to the xDSL TPC-TC interface• A telephone terminal functional interface



• A set of procedures that use the TPS-TC and functional interface to describe voice functionsand procedures

Benefits in the definition of a G.voice Recommendation include the removal of any voicecomplexities and details from a PHY layer Recommendation, and abstracting the technical detail ofhanding voice through a functional interface. Also, with a well defined voice functional interface,other technical groups can use the functional interface to define PHY layer transport of the requiredvoice functions.

G.dmt.bis (Discrete MultiTone)

TD-010(WP1/15) (F. Van der Putten, Alcatel Bell, Editor) provides the current draft of theG.dmt.bis Recommendation. It includes several proposals and some working text and descriptionsthat Q4/15 is undertaking. It also includes revision marks reflecting the changes agreed at theClearwater interim meeting. TD-011R1(WP1/15) ((F. Van der Putten, Alcatel Bell, Editor) is theG.dmt.bis issues list; it reflects the changes proposed at this meeting which are all reported underG.gen, above.

G.994.1, G.hs.bis (Hand Shake)

TD-039(Plen) (L. Brown, Conexant, Editor) contains proposed changes to the draft text of G.994.1(COM15-4-E) that was up for Decision at this meeting. No new issues list was issued. Thesechanges primarily include:

• Addition of new code point tables• Editorial work to allow G.994.1 (2001) to include both the functionality of G.994.1 (1999,

Revision 1) and the new message and transactions of Revision 2 so that G.994.1 (1999) may bewithdrawn

• Other editorial cleanup, such as fixing incorrect Table numbering

TD-003(Plen) (L. Brown, Conexant) contains additional code points requested by Q4/15 forinclusion in the version of G.994.1 that is for Decision at this meeting including G.991.2 Annex Aand B, Committee T1 MCM VDSL, and ETSI SCM and MCM VDSL.

D.39 (S. Palm, Broadcom; Infineon, Metalink) proposes a codepoint in G.994.1 for “CommitteeT1 SCM VDSL” mode. In the recent ITU-T meeting, a codepoint in G.994.1 was agreed for“Committee T1 DMT (MCM) VDSL”. D.39 proposes that the other of the two reserved SPar(1)bits for Committee T1 be assigned as “Committee T1 SCM VDSL” mode.

D.63 (T. Pollet, Alcatel Bell; J. Boström, Ericsson; M. Park, Samsung AIT; Telia) proposes ahandshake carrier set, D43, to support the two DMT/MCM VDSL modes of operation defined inthe Spar(1) coding of the standard information fields in the revised Recommendation G.994.1,which is up for Approval. This proposed carrier set addresses a late discovery of a problem relatedto the use of G.hs in Committee T1 DMT VDSL and ETSI MCM VDSL.

The current defined carrier sets for the 4.3125 kHz signaling family (i.e., A43, B43, and C43), useupstream carriers that overlap with the first downstream band of the VDSL band plans defined inthe regional VDSL standards documents. The proposed D43 carrier set specifies an upstream,downstream carrier set that lays in the upstream, downstream VDSL signal transmission band,respectively. VDSL may be used in regimes of operation where the spectral content of the VDSLsignal is located essentially at high frequencies (i.e., above 1.104 MHz). In this case, the use of anexisting carrier set may imply unnecessary functionality to be added to the transceiver.



This proposed handshake carrier set is defined in the 4.3125 kHz signaling family, with the duplexonly transmission mode as a mandatory carrier set associated with Committee T1 DMT VDSL andETSI MCM VDSL. The symbol rate should be 4312.5 / 8 = 539.0625 symbols per second, asdefined in G.994.1.

D.69 (C. Del-Toso, ST Microelectronics, France) is the same as D.63.

D.70 (O. Micka, Metalink; Infineon) proposes to add to G.hs two new carrier sets, B4 and C4,where B4 is mandatory in SCM-based VDSL modems.

G.995.1, G.ref.bis (Overview)

TD-026(WP1/15) (S. Abbas, Centillium, Editor) is the updated issues list for G.ref.ter, based oncontributions uploaded and presented at the close of this meeting.

TD-012(WP1/15) (S. Abbas, Centillium, Editor) is the issues list for G.ref.bis based oncontributions uploaded and presented at the close of the Q4/15 January 2001 Clearwater meeting.

COM15-20 (S. Abbas, Centillium, Editor) is the draft revised Recommendation G.995.1, Overviewof DSL Recommendations, for Approval. This Recommendation provides an overview of thefamily of DSL Recommendations. It describes how the various DSL Recommendations arerelated. It also defines a generic system reference and a protocol reference configuration for DSLRecommendations, and relates both to the system reference models of the DSL Recommendations.This Recommendation is of an informative nature and does not imply any specific requirements.

D.38 (S. Abbas, Centillium) depicts two scenarios showing the G.voice protocol architectureplacement on the remote side, based on the generic reference configuration in G.995.1. Onescenario shows the cases where all the reference points are exposed and voice is carried over aG.pnt or similar kind of network inside the home. In this case, a gamma-H cross layer interfacedefinition would be useful. The scope of G.voice on the T reference point side is then similar tothat of the U side. The other scenario depicts the case where none of the T, S, and R referencepoints are physically exposed. In this case, while G.voice provides gamma-R interface definition onthe U side, a voice functional interface definition would be useful for the voice terminal equipmentadaptation.

It was agreed that Figures 1 and 2 in D.38 can be used to clarify the G.voice protocol architectureplacement philosophy on the remote side; they will be incorporated, with modifications, into Section0 of G.ref.ter.

G.eval

D.36 (Conexant, Lucent (Agere Systems), Paradyne, Vocal Technologies) contains a proposal for anew project, G.eval, to develop a set of recommendations for performance evaluation of xDSLsystems that include both the central site and remote client modems. This issue was opened underG.test. This set of recommendations can be used by network service providers, test houses,magazines, users, and designers to evaluate and compare modem performance in terms of networkmodel coverage (NMC).

The current xDSL test Recommendation (G.996.1) contains network models and test proceduresfor verifying DSL transceiver conformance to the performance requirements contained in each ofthe G.99x DSL transceiver Recommendations. A network model and test procedures for evaluatingand comparing modem performance are needed. A methodology for analog modem performancetesting in ITU-T Recommendations V.56.bis and V.56.ter, developed in what is currently SG16,



does currently exist. A similar approach has been taken in TIA PN-4254, the North Americannetwork access transmission model for evaluating xDSL modem performance. Furthermore, TIAPN-4255 specifies test procedures to be used in conjunction with this model.

D.36 proposes that the first recommendation developed by this new project, G.eval, should be theInternational network access transmission model for evaluating xDSL modem performance. Acompanion Recommendation, Test procedures for evaluating xDSL system performance, shouldalso be developed. The proposed scope for the project is as follows:

• The network model recommendation shall:– Define the network access characteristics and associated impairments– Specify configuration and setup of simulator equipment

• The test procedures recommendation shall:– Define how to use the network model– Define a set of repeatable test procedures designed to characterize the performance of

modems– Specify precise configuration of all required test equipment– Provide step-by-step instructions for performing each test– Provide recommended formats for analyzing, interpreting, and presenting results

D.37 (Conexant, Lucent (Agere Systems), Paradyne, Vocal Technologies) is a copy of PN-4254-INT Draft 1, International network access transmission model for evaluating xDSL modemperformance, provided by TIA TR-30.3 for comment, questions, and/or recommendations. Themethodology used in this proposed standard is similar to the methodology used in prior TIATSB37A, TIA/EIA-3700, TIA/EIA-793, and ITU-T V.56.bis analog modem test standards writtenby TR-30.3. The purpose of these standards is distinctly different from the following DSL testingstandards:

• ITU recommendation G.996.1, Test procedures for DSL transceivers, contains network modelsand test procedures for verifying DSL transceiver conformance to the performancerequirements contained in each of the G.99X DSL transceiver Recommendations.

• DSL Forum TR-029, ADSL Dynamic interoperability testing, contains test suites and testprocedures to determine the level of interoperability between different vendor brands of ATU-Cs and STU-Rs.

The model will need to be revised based on actual rollout of DSL services, because some importantelements of the model (e.g., crosstalk disturber model) are based on projections.

Q5/15 WP2, Management Aspects of Signal Processing NetworkElements

Y. Naito (Mitsubishi Electric) is the Q5/15 Rapporteur. TD-022(WP2/15) is the agenda for thismeeting. TD-023(WP2/15) is the list of Q5/15 documents. Eight members participated in thismeeting.

TD-021(WP2/15) is the report of the Q5/15 interim meeting held January 31 – February 2, 2001 inGeneva. Q5/15 made advances in drafting new Recommendations G.768 and I.733. Q5/15 alsomade progress in the discussion of G.ipcme.

An ITU-T email reflector has been created for Q5/15. To subscribe to the Q5/15 email exploderlist, send an email to <[email protected]> with the following in the message body: Subscribetsg15q5. A new web discussion board has been created: <http://skene.org/q5>



Q5/15 plans to hold a meeting in April 2001 to advance the work on drafting I.733 and G.ipcme,and to discuss resolution against any comments received on G.768, during AAP.

G.768 (8k DCME)

TD-024(Plen) (Y. Naito, Mitsubishi Electric, Rapporteur) is the new draft Recommendation G.768(8k DCME) v.4.1; it was submitted for Consent at the Plenary. This Recommendation specifies theelements of DCME using 8 kbit/s CS-ACELP, digital speech interpolation (DSI) and facsimiledemodulation/remodulation, to achieve interworking of such equipment. It specifies extensions anddeviations for Recommendations G.763, G.766, and G.767, which specify a 32 kbit/s ADPCMDCME, and facsimile demodulation/remodulation, and 16 kbit/s LD-CELP DCME, respectively.

TD-024Add1(Plen) (Y. Naito, Mitsubishi Electric, Rapporteur) contains the proposed texts for theSummary and for the replacement of relevant existing text of Section 8.3.2.3 and Section 9.2 fornew draft Recommendation G.768 v. 4.1 in TD-024(Plen). Consequently, all the Table numbersfrom 3 to 11 in TD-024(Plen) shall be increased by 1.

D.77 (Mitsubishi Electric) identifies the number of assignment messages necessary forcorresponding DSI trunk channel pool and the maximum number of messages to be generatedwithin a single G.768 DCME. At the September 2000 WP2 Rapporteurs meeting in Munich,Q5/15 agreed on a proposed control channel structure capable of transmitting four messages/framein basic capacity and another four messages/frame (for a total of eight messages/frame) inexpanded capacity (Q6-D.04, Y. Naito, Mitsubishi Electric). It was also agreed that the criteria todetermine whether to have basic CC (Control Channel) capacity or expanded CC capacity shoulddepend on the capacity of IT pool size. It was also recognized that, based on the results of channelassignment simulation, up to about 230 ITs can be accommodated by basic CC capacity of fourmessages/frame.

D.77 reviews the results of further analysis and proposes the threshold number of IT (IntermediateTrunk) to determine whether the corresponding clique should have basic CC or expanded CC. Italso identifies the maximum numbers of assignment messages to be generated within a singleG.768 DCME. It concludes that a DSI bearer shall implement basic control channel (32 kbit/s forfour messages/frame) if the number of DSI trunk channels is equal or less than 240. If the numberof DSI trunk exceeds 241, the bearer shall implement expanded control channel (48 kbit/s for eightmessages/frame).

Considering the fact that larger size clique with expanded CC occupied more than 13 TS (TimeSlot, 64 kbit/s) and even the minimum size clique requires more than 3 TS, the combination oftransmission bearers in a single 2048 kbit/s stream shall be as follows:

• Four or less smaller size cliques• One larger size clique and three or less smaller cliques• Two larger size cliques and one or no smaller size clique

The maximum numbers of assignment messages required for each case are 16, 20, and 20,respectively. A single DCME shall be capable of generating and transmitting up to 20 assignmentmessages. Since there is a possibility for a DCME to receive up to four larger size bearers fromdifferent destinations in multi-destination mode, DCME receive units shall be capable of processingup to 32 assignment messages.

D.78 (Y. Naito, Mitsubishi Electric) proposes the bit bank handling procedure in G.768 DCME tocreate a 40 kbit/s channel for VBD signal transmission. A basic agreement was made to take the



same scheme as in G.763 for bit bank handling; Recommendation G.767 also uses the sameprinciple. The deviation from the original G.763 description and succeeding G.767 descriptionarises mainly from the differences in IT and BC numbering. D.78 proposes that the followingdescriptions supersede corresponding descriptions for bit bank handling in Rec. G.763:

• The assignment message for bit bank handling shall consist of the youngest BC number of theBCs used for bit-bank, IT number 637 and Synchronous data word of “0000”

• Each bit bank should occupy four consecutive BCs, starting from BC number = m and endingBC number m+, where m = (4 x i ) + 1 (i = 0, 1, 2, ….60)

D.79 (Y. Naito, Mitsubishi Electric) lists the assignment messages to be used in G.768 DCME,compared with conventional G.763 DCME and G.767 DCME. A 10th message for Channel CheckTest disconnection is added to avoid CCT sequence to stay on the same BC in case the channelactivity is rather low. The details of the procedure for generating Channel Check Testdisconnection message is as follows:

When a CCT signal connected to a BC becomes inactive, the connection shall be disconnected. Thetransmit unit shall execute the disconnection procedure and send out an assignment messagecomposed of the corresponding BC number and the synchronous data word of “0000”. Onreceiving this message, the receive unit shall disconnect the corresponding BC and the special testport. The associated BC, encoder, and decoder shall become free.

D.80 (Y. Naito, Mitsubishi Electric) proposes the use of G.726 16 kbit/s ADPCM codec for thetransmission of DTMF signals in G.768 DCME and I.733 VAME. The 8/6.4 kbit/s CS-ACELPcodec conforming to ITU-T Recommendation G.729 cannot provide the sufficient transmissioncapability for No. 5 signaling tone signals. The G.726 ADPCM coding algorithm is apparentlyconsidered as a waveform coding algorithm that attempts to transfer, as much as possible, theoriginal waveform of input signals. The main difference in performance between the different bitrate modes of the G.726 speech coding algorithm is the quantization noise level; the frequencycharacteristics are common to all bit-rates. G.728 LD-CELP coding algorithm, although showingrather good transmission quality even for the tone signals, is one of the typical source codingalgorithms most strongly customized to human voice characteristics. Since No. 5 tone signalingsignals are inter-switch signaling signals and no analog subscriber lines are included in thetransmission path, input/output S/N can be considered as a less important factor.

This problem was reported in IEEE Communication Magazine (“Performance of ITU-T G.729 8kbit/s CS-ACELP speech codec with non-voice narrowband signals,” September 1997). Tosupport No. 5 signaling tone transmission in G.768 DCME, adoption of an alternative codingscheme with stable transmission quality for MF tone signals and minimum bit rate is required.

D.81 (Y. Naito, Mitsubishi Electric) proposes an overload channel creation scheme in G.768DCME. Instead of variable bit rate operation using 30/24/16 kbit/s ADPCM, 8/6.4 kbits/s variablebit operation of G.729 CS-ACELP codec will be used in G.768 DCME. The basic concept is totake the same procedure as in G.763, and describe the deviation from the original G.763descriptions caused by the difference of coding bit rate and BC numbering.

D.82 (Y. Naito, Mitsubishi Electric) proposes the compensation of speech codec processing delaysin G.768 DCME and I.733 VAME. It was agreed to use two different types of speech codingalgorithms in G.768 DCME: G.729 CS-ACELP codec in 8/6.4 kbit/s operation for normal speechsignals, and G.728 Annex J LD-CELP codec in 40 kbit/s operation for voiceband data signals.Additionally, the use of G.726 ADPCM codec in 16 kbit/s operation for No. 5 signaling tonesignals was proposed. The same type of switchover between the different types of codecs shouldalso exist in I.733 VAME. The use of different speech codecs in a single piece of equipment can



result in differences of processing delay, which must be absorbed independently within the transmitunit and the receive unit. The theoretical algorithmic delays to be considered for encoding are:

• 8/6.4 kbit/s CS-ACELP: 15 msec (5 msec Look-ahead delay + 10 msec coding frame)• 40 kbit/s LD-CELP: 2.5 msec (2.5 msec coding frame)• 16 kbit/s ADPCM: 125 microsec (125 microsec coding frame)• The processing delay in decodings depends on the decoder design

D.82 proposes that this issue be explicitly addressed in the draft Recommendations G.768 andI.733.

TD-007(WP2/15) is a reply from SG16 to the SG15 liaison regarding external reset of a speechcodec used together with a DTX mechanism in circuit multiplication equipment. SG16 discussedthe issue; they prefer the existence of a synchronous reset capability in CME using the G.728algorithm. Aligning the internal status of the encoder and decoder of G.728 using an externalsynchronous reset will benefit speech quality, particularly at the transient from silence to activespeech when the codec is used under DTX condition in CME. SG16 expects no negative effects onspeech quality because of synchronous reset for G.729 under DTX function in CME. SG16intends to submit experimental results to SG15 showing the effect of synchronous reset on thespeech quality for G.729.

Q5/15 agreed to introduce the synchronous reset between the encoder and corresponding decoderon all the codecs used in G.768 DCME and I.733 VAME (G.726 ADPCM, G.728 LD-CELP, andG.729 CS-ACELP). It was also agreed to include synchronous reset capability of codecs into theexisting Recommendation G.767 at its next revision. It was agreed to send a liaison to SG16, tothank them for the information on the G.728 codec, to ask for formal input on the G.729 codec, andto advise them to publish this useful information as some type of formal document. This liaison(included in TD-036(Plen)) was sent jointly from Q5 and Q8/15.

All the agreements made at the January 31 – February 2, 2001 Geneva meeting to include newproposals into draft new Recommendation G.768 and I.733 , including the inclusion ofsynchronous reset of the codecs, were confirmed. The items to be included are:

• Inclusion of LRE codec synchronous reset capability in G.768 and I.733 (as stated above)• Criterion to select BCC or ECC in correspondence to the number of ITs belonging to the clique• Number of CC messages to be generated in G.768 DCME• Scheme for creating 40 kbit/s channels• Scheme for overload channel creation• Types of assignment messages to be used in 8k DCME• Compensation of processing delay between the different types of codecs• Use of G.726 16 kbit/s ADPCM codec for SS No. 5 tone signals

I.733, VAME

TD-029(WP2/15) (Y. Naito, Mitsubishi Electric, Rapporteur) is the latest draft of the newRecommendation I.733 v.4.0, Voice cell assembly/disassembly compression equipment. Thepurpose of a voice on ATM multiplication equipment (VAME) is to provide a means ofaugmenting the traffic capacity of ATM facilities operating between international switching centers(ISCs) and sources of ATM traffic. In addition to providing traditional DCME functions, theequipment will have additional capabilities such as ATM multiplexing to optimize bandwidthutilization.



IP-CME

TD-024(WP2/15) (H. Yamada, KDDI) provides the baseline document for RecommendationG.ipcme, IP-based circuit multiplexing equipment, in accordance with the scope issues discussed inthe WP2 September 2000 Munich meeting. IP-CME constitutes a general class of equipment thatpermits concentration of a number of IP ports on a reduced number of transmission channels overIP-based networks.

It was agreed to send the information regarding the drafting work currently done in Q5/15 forG.ipcme to SG12 and SG13 (liaison included in TD-036(Plen)).

Q6/15 WP2, Circuit Multiplication Equipment and Systems

B. Reeves (BT) is the Rapporteur. Q6/15 is a new Question combining the old Q6/15 and Q7/15work. TD-009(WP2/15) is the report of the Q6/15 September 2000 meeting in Munich. TD-025(WP2/15) is the report of the Q7/15 (old, Q6/15 new) January - February 2001 meeting inGeneva.

There is a new Q6/15 email exploder. A web discussion board has also been set up and has beenused for some discussion; it can be found at <http://www.skene.org/q6>.

Further work on the development of Recommendations G.168 (2002) and new RecommendationG.ved will be carried out during one interim meeting planned for April 2001.

Recommendation G.168 (2002), Digital Network Echo Cancelers

TD-043(Plen) (B. Reeves, BT) contains the Agreed text of the proposed Implementers Guide forRecommendation G.168; it was submitted for Approval at the Plenary. Appendix II of G.168(2002) was modified to include the non-intrusive measurement method discussed in COM15-26,Results of ECHO Return Loss (ERL) Measurements in European public switched telephonenetworks (Telia AB). A reference to the results contained in COM15-26 was added to Appendix II.A proposal to add a reference to COM15-146, Measurement Methods of Echo-Paths and TheirCharacteristics In North American Networks (Nortel Networks, Canada), which contains ERLmeasurements for North America, was not agreed.

D.04 (M. Givens, Tellabs) proposes a correction to Test 10a. Least-squares estimators minimizethe squared error by generating a solution to the normal equation

xyxx rh 1−= R

where Rxx is the auto-correlation matrix of the input signal vector, and rxy is the cross-correlationvector between the input signal vector and what is called the desired signal. In the case of the echocanceler, the desired signal is the echo. Least-squares estimators rely on an estimation of theinverse of the auto-correlation matrix of the input signal vector to form the so-called “optimal”solution represented by the above normal equation. A unique solution will exist if, and only if, theinverse of Rxx exists. When Rxx is singular, as is the case with deterministic (e.g., narrow-bandsinusoidal) signals, the inverse does not exist, and the solution to the normal equation is not unique.It has been shown that the traditional analysis of the LMS algorithm is not valid for deterministicsignals (J. R. Glover, “Adaptive noise canceling applied to sinusoidal interferences,” IEEE Trans.Acoust., Speech, Signal Processing, vol. ASSP-25, pp. 484 – 491, 1977). P. M. Clarkson,“Optimal and adaptive signal processing,” p. 186 – 192, CRC Press, Boca Raton, 1993) showedthat for an input signal of the form



)cos()( 0 += nTAkx

each element, r(n), of the auto-correlation matrix Rxx is given by

)cos(2

)( 0

2

nTA

nr =

This results in an adaptive filter whose filter coefficients attain a sinusoidal form and it functions asa notch filter. The response to a sinusoidal input signal is a well-known and understoodconsequence of the least-squares algorithm. It is precisely this behavior that is a problem with Test10a. When the echo of the CED (2100 Hz) signal ends, input samples remain in the input buffer ofthe adaptive filter. This remaining signal is convolved with the adaptive filter, and an anti-echo isproduced. With wideband signals, the adaptive filter coefficients would generate a model of theimpulse response. This model would have a zero value for those input buffer samples after theecho ceases.

With a sinusoid, this is not the case; no filter coefficient has a zero value. An anti-echo is producedafter the echo ceases, and is seen as a signal on the output of the echo canceler. The CED in Test10a is followed by silence of nominally 75 ms. At the beginning of this silence period, the echocanceler will produce an anti-noise that will exceed the limits of the test in this area.

To eliminate this problem, D.04 proposes that the G.168 Implementers Guide modify Region II ofTest 10a so that it ends at the end of the CED signal, with Region III remaining as-is. Alternatively,the maximum level of the output signal can be increased to (–13 – Aecho ) dBm0 during the silenceperiod following the CED signal.

D.40 (H. Kullmann, Deutsche Telekom) discusses the performance of echo cancelers with ITU-Tlow-bit rate coders in the echo path, the proposed new Test 13 of G.168 that was agreed by Q7/15at the September WP2 Rapporteurs meeting in Munich. It shows that ADPCM coders in the echopath may influence the convergence characteristics of an echo canceler, such as convergence speedand residual echo attenuation. It reports on measurements that were carried out with two echocancelers including an ADPCM coder in the echo path. Comparative investigations were includedusing real speech and the composite source signal. It was found that the deterioration of theresidual echo level may exceed 8 dB and more. The convergence speed decreases as well.Enabling the non-linear processor will lead to increasing switching, which may influence the speechquality performance of an echo canceler and the network.

The current Test 13 states: “For the stated ITU-T coders, the residual echo power measured withthe echo canceler enabled should be equal to or less than the measured baseline with the echocanceler disabled. The coders for which this test is applicable are to be stated by the user.” Basedon the requirement of Test 13, and the measurement results presented, D.40 draws the followingconclusions:

The current Test 13 can be passed, but the “returned echo” may be disturbed by the switching ofthe NLP. Therefore, the speech quality performance of the network may be more degraded thanwith an echo canceler in the disabled mode. The impact on speech quality performance is stillunknown.

Regarding the current requirements of Test 13, the practical use is very limited. It seems to notmake sense to deploy echo cancelers in connections with low-bit rate coders in the echo path. If theERL value of a connection including echo cancelers with low-bit rate codecs in the echo path is low,for network planning purposes it is very useful to know what degradation low-bit rate coders may



cause, compared to the performance of the echo cancelers in the same connection but without thelow-bit rate codecs. An echo canceler should still provide a certain amount of echo return lossenhancement.

Based on these conclusions, D.40 proposes a number of changes for Test 13 and Appendix I.

Q6/15 agreed to make changes to Test 13 and the associated elements of Appendix I as discussedin D.40, but did not agree to the proposed use of a table to indicate performance requirements forindividual codecs. New text for Test 13 was agreed (given in TD-034(Plen)).

D.49 (V. Turbin, France Telecom) presents hybrid measurements performed in the France Telecomnetwork, and compares them to the models currently included in Annex D of G.168. Annex Dprovides echo path models for testing speech echo cancelers; the use of these models enables in-labtesting of the echo cancelers in conditions very close to those encountered in real networks.However, the models included in Annex D correspond to hybrids either computed with a networkhybrid simulator or measured in North American networks. Since network characteristics varyfrom network to network, each network provider is faced with the following question: Do thesemodels apply to my network? To answer this important question, France Telecom performedhybrid measurements in its network. D.49 asserts the following conclusions:

• Annex D with its eight models is quite complete and is adequate to the needs of FranceTelecom.

• If even only three types of impulse response emerged from the multiple tested configurations,for any given echo path model type, the echo return loss could be very different from oneconfiguration to another, with a difference as high as 10 dB. This clearly shows that echocancelers deployed in real networks are faced with a wide range of ERL values. This resultunderlines the fact that ERL values must not be specified in ITU-T Recommendation G.168.The statement ‘ERL > 6 dB’ has to remain the only valid one.

TD-006(WP2/15) is a liaison from ITU-T SG16 addressing (1) issues with Recommendation V.18text telephone transmission through network echo cancelers, and (2) issues with V.34 faxtransmission through network echo cancelers.

(1) At the February 2000 SG16 meeting, D.319 (USA) alerted Q9/16 to potential problems withV.18 text telephone communication through network echo cancelers. At that time, it wasrecommended that newly designed terminals use ANSam with phase reversals to avoid the problem.Text telephones are used by hearing-impaired people for communication via text messagesaccording to the protocols defined in ITU-T Recommendation V.18, Operational and interworkingrequirements for DCEs operating in the text telephone mode. Members of Q9/16 now report thatexisting terminals with legacy submodes of V.18 also experience difficulties; the problem occursboth intranationally and internationally. Many V.21 and V.23 based text telephones are currentlyused daily by hard-of-hearing, deaf, and speech-impaired users; it is important to avoid degradationof service for these users. The echo cancelers involved are of designs that should follow G.168,which contains a Test 14 defined to verify that low speed modem traffic is transmitted properlythrough the echo canceler. Q9/16 asks that SG15 review Test 14 to determine whether it needsredefinition to include testing for the types of text telephone communication described in ITU-TV.18 including all its annexes defining legacy modes. These matters will now be addressed byQuestion H/16 (old Q9/16).

(2) At the February 2000 SG8 meeting, a liaison received from Q7/15 described the progress of thestudy of the issue concerning the use of V.34 fax performance through network echo cancelers(TD-293, Y. Tao, Lucent). This issue was originally discussed at the SG8 meeting in March 1999.It is still open and requires a resolution for Q14/16 (Facsimile matters previously under Q1/8 arenow addressed by Q14/16).



SG15 studied this issue and performed a series of laboratory and network tests. Test resultsdemonstrated that a possible cause of these failures may be found in the operation of the non-linearprocessor (NLP) of the echo canceler at the called station side when there exists a significant levelimbalance in the network. Q7/15 felt that it would be beneficial for overall fax and dataperformance to amend Recommendation G.168 (2000). Such an amendment should include anoptional tone disabler capability that will turn off the NLP on the detection of a 2100 Hz tonewithout phase reversals and with or without amplitude modulation (ANSam). Further tests wereproposed to verify, before the April 2000 SG15 meeting, that this fix would cure the problem in thenetwork. These tests verified that this proposed fix in G.168 (2000) did resolve the problem. Then,at the April 2000 SG15 meeting it was proposed that the new tone disabler requirement be mademandatory in G.168 (2000).

At the February 2000 SG8 meeting, the amendment to Recommendation T.30 to make the phasereversal to ANSam for disabling the echo canceler mandatory was postponed, to wait for an answerfrom SG15. Q14/16 asks SG15 to inform them of their conclusions from their investigation onthis issue with regard to Recommendation G.168 (2000).

D.57 (B. Reeves, BT) reports on the performance of text telephones when used in connections withnetwork echo cancelers. Three different network echo cancelers were used in the tests described,each stating compliance with Recommendation G.168. Seven different network conditions wereused that were designed to represent a range of different network scenarios. A test procedureaccording to G.168 Test 14 was followed to perform the tests, where the performance with andwithout the network echo canceler was compared.

The text telephones used in the tests covered the range of protocols defined in RecommendationV.18. These protocols are: V.18, V.21, V.23, EDT, Baudot, Bell 103, and DTMF. With no echocanceler in the connection, all but one of the calls were successful (245 total), indicating a highsuccess rate over the range of network conditions tested. With the echo canceler enabled, thesuccess rate went down. Echo canceler C performed the best with only four failures in 245 calls.Echo canceler A was significantly worse with 116 failures out of 210 calls, and echo canceler Bgave 83 failures out of 175 calls. All three echo cancelers performed well with Baudot and EDTprotocols, where 100% success rate was obtained.

Test 14 of Recommendation G.168 covers the performance of echo cancelers with V-series low-speed data modems. D.57 proposes that the following wording be added to this test inRecommendation G.168 (2002) to ensure that in the future echo canceler manufacturers andnetwork operators will be reminded to test performance with V.18 compatible text telephones:

This test is meant to ensure that echo cancelers will not impair the performance of V.-serieslow-speed (< 9.6 kbit/s) modems, including V.22.bis modems, and V.18 compatible texttelephones, which do not send a 2100 Hz disable tone with phase-reversals. The bit-error rate ismeasured while the echo cancelers operate in a simulated network with low-speed data modems.

Q6/15 agreed to include wording in Test 14 to reference the testing of V.18 text telephones, and toadd Recommendation V.18 to the list of references. During the discussion, it was noted that sometext telephones that implement legacy modulation schemes may not issue a 2100 Hz answer tone.It was agreed to send a liaison to SG16 (included in TD-036(Plen)) informing them of the changesagreed to Recommendation G.168 with respect to the performance of echo cancelers with V.18 texttelephones.

D.89 (M. Givens, Tellabs) provides a clarification of Figure 15/G.168. Figure 15/G.168 hascaused confusion among some users. The legends in the figure can be ambiguous. For example,does the legend “N = -55 dBm0” apply to the upper graph or the middle graph? Since Part C of



the test does not refer to the Test 2B steady-state requirements, the lower graph seems unnecessary.D.89 proposes a figure to replace the current figure, and proposes that the new figure be included inthe Implementers Guide.

New Voice Enhancement Device (VED) Recommendation

TD-028(WP2/15) (B. Reeves, BT, Rapporteur) is the draft Recommendation G.ved (voiceenhancement devices). This Recommendation applies to the characteristics, performance, andtesting of voice enhancement devices (VED) intended for use in digital network-based equipmentfor mobile applications. A VED is defined as any signal processing in the digital transmission paththat performs voice enhancement functions on voiceband signals that traverse mobile networks.Voice enhancement functions include the control of acoustic echo generated by wireless handsets,noise reduction, and the recognition and accommodation of tandem free operation (TFO) andinterworking function (IWF) signals.

The purpose of this Recommendation is to define certain performance constraints for VEDs and,where appropriate, to define laboratory tests that may be performed on a VED to verify that theseconstraints are met. A VED that satisfies all the constraints and passes all of the tests in thisRecommendation should ensure, but will not guarantee, that the pre-existing standard of overallnetwork performance, e.g., the transmission of speech, voiceband data and other voiceband signals,ISDN, etc., is not degraded when the VED is installed in the network.

Rec. G.ved describes the general characteristics of VEDs and indicates what characteristics areimportant to provide acceptable performance in the network. It also discusses issues related to theinteraction of VEDs with other network and subscriber equipment. It does not define a standardalgorithm, nor does it apply to either electrical echo control (governed by G.168) or automatic levelcontrol (governed by G.169). Note that the VED may be incorporated into other networkequipment such as the transcoder or the electrical echo canceler. In this case, the performancerequirements of Rec. G.ved refer to the performance of the VED only.

D.05 (M. Givens, Tellabs) proposes editorial changes to the text of the scope for the newRecommendation on network voice enhancement devices (VED) for mobile applications that waspresented at the September 2000 WP2 Rapporteurs meeting in Munich (MUN7-24R1).

Q7/15 WP2, Transport Network Equipment for Interconnecting GSTNand IP Networks

J. Skene (Tellabs) is the Q7/15 (previously Q21/15) Rapporteur. TD-026(WP2/15) is the agendafor this meeting of Q7/15, Transport network equipment for interconnecting GSTN and IPnetworks; TD-027(WP2/15) is the document list. Eleven people attended this meeting. TD-011(WP2/15) is the report of the old Q21/15 (now Q7/15) September 2000 meeting in Munich.Q7/15 liaisons were covered in the Q8/15 meeting (below).

A Q7/15 interim meeting is planned for April 2001 to prepare Recommendation G.799.1 forDetermination at the next SG15 meeting in October, 2001.

G.799.1, TIGIN

TD-016(WP2/15) contains the draft Recommendation G.799.1 v3.5, Functionality and interfacespecifications for GSTN transport network equipment for interconnecting GSTN and IP networks;it incorporates the changes agreed at the September 2000 Munich meeting. In discussion, thefollowing agreements were made:



• Add a discussion thread for section 3.5, Management interface, to the Q7 discussion site.Contributions are encouraged.

• Include reference in section 4.1.1.3 on direct control of non-associated SPNEs via direct H.248control links.

• After a discussion on silence compression/comfort noise generation, it was agreed to send aliaison requesting text for inclusion into G.799.1 Section 4.1.3 to SG16, where work isprogressing on this topic.

• Make mention in Section 4.1.6 that speech coders in a TIGIN gateway should followestablished rules for speech reconstruction under conditions of lost packets.

• Split Section 4.2, Voiceband quality, into two subsections, one for voice quality and one forvoiceband data quality, and subdivide the latter into voiceband data modems, facsimile, and texttelephones. It was also agreed to send a liaison to SG12 asking for suggestions for text to beincorporated into the section on voice quality. Corresponding discussion threads will be addedto the Q7 web-based discussion site.

• Include in the appropriate subsection of Section 4 the information on synchronous coder resetfrom liaison TD-007(WP2/15).

• Add a definition of a TIGIN gateway to Section 1.3.• Clarify the use of the terms “voice” and “speech.”• Add the abbreviations: RTP, AVR, TMN, SNMP, SCN, and VBD.• Change the Scope to indicate that specific coverage of ATM on the TDM interface is not

covered by this first release of Recommendation G.799.1.• Update Section 1.1, Normative references, to include all appropriate references in the document.• Add SIP to Figure 2• Add reference to ITU-T Recommendation E.370, when this is approved.• Send a liaison to SG16 requesting guidance on procedures to be followed under conditions of

IP network congestion requiring codec re-negotiation. It was not clear whether this was coveredin H.323.

• Add an arrow to Figures 3, 4, 5, and descriptive text in Section 4.1.1.1 indicating the source anddirection of echo.

• Move the second paragraph of Section 4.1.1.3 on Q.115 to Section 4.1.1.• Add a comment on the acceptability of tandeming echo cancelers to Section 4.1.1.• Add a note asking for contributions on the implications of tandeming TIGIN gateways to

Appendix III, and add this to the living list.• Remove the word “optional” from Figure 5.• Change the word “coder” to “codec” in Section 4.1.2.• Check H.232 to see if it refers to coding or transcoding, and change G.799.1 accordingly.• Add a note requesting contributions to the text of Section 4.1.2, and add this to the living list.• Add a statement in Section 4.1.2 advising that voice coding should impose the minimum delay

possible.• Add a new subsection within Section 4.6 on maintenance testing. Contributions on this section

were requested, and a thread on this topic will be added to the Q7 discussion site.• Change the abbreviation VOIP to VoIP.• Change reference in G.799.1 to TIGIN, and to always refer to TIGIN gateway rather than just

TIGIN.

TD-014(WP2/15) contains the living list of open issues for Recommendation G.799.1, it wasupdated December 15, 2000. The main points of this list have been entered on the Q7 discussionsite as independent threads.

Q7/15 discussed the Q7/15 workplan (Working document 7-4) . Several items (items 5, 6, 7, 8, 9,and 13) were considered to be associated with the interaction of signal processing in the IP gatewaywith other elements of the network, and therefore more suitable to be addressed by the new Q8/15.The Q8 and Q7 Rapporteurs agreed to determine which items fall into this category; the workplan



will be updated accordingly. A joint meeting of Q7 and Q8 at the next meeting will discuss theseissues.

Item 10 includes a discussion of facsimile traffic in a voice gateway. G.799.1 currently containslittle reference to fax traffic. It was agreed that the Rapporteur will find out where fax over IP isbeing handled, and Q7/15 will send a liaison asking for suggested text to be included in G.799.1.

Item 13 includes a discussion on evolving terminal equipment; it was decided that text telephonesshould be included here. Q7/15 agreed to send a liaison, requesting information on text to beincluded in G.799.1 on this topic, to QH/16 where there are experts in this field.

It was pointed out that, as H.248 is used to control a G.799.1 gateway, additional H.248 packagesmay be required to support the various features of a TIGIN gateway. Contributions on this wererequested.

Items 15, 16 and 17 were considered to be redundant; it was agreed delete them.

It was pointed out that the workplan does not specifically mention support of wireless interfaces,although the TIGIN gateway supports GSTN interfaces that implicitly includes wireless. This willbe included in the next version of the workplan. In addition, the Rapporteur will send liaisons toappropriate, recognized standards organizations informing them of the work being done in thisquestion. Possible organizations include 3GPP and ITU-T SSG. The status of contact with 3GPPwill be checked before a liaison is sent. In addition, a liaison will be sent to ITU-T SG13 asking fortheir guidance with respect to UMTS as the lead study group on IP.

EDH Issues

TD-015(WP2/15) (J. Skene, Tellabs, Rapporteur) addresses EDH Issues for Q7/15. The ITU ingeneral, and Q7/15 in particular, is making more use of electronic data handling (EDH) to speed upits work; TD-015(WP2/15) describes these tools.

To sign up as a subscriber to the Question 7/15 email exploder list, send an email to<[email protected]> with the following in the message body: Subscribe tsg15q7

The ITU provides an informal FTP Area (IFA), which serves as a central repository for documents.All general meeting documents are available here just before a Geneva meeting. Workingdocuments for interim meetings are also kept here. An attempt is made to keep the home page forQ7/15 up to date, with notes on the next interim meeting, pointers to directories, etc.

The informal FTP Area (IFA) home page for Q7/15 is located at:

<http://ftp.itu.int/u/tsg15/sg15/wp2/q7/q7_index.htm>. A valid TIES account with userID and TIESpassword is required to access this site.

A mirror site has been created that may provide faster access. This is located at:<ftp://tellabs_itu:[email protected]/tellabs_itu/ITUMirror/SG15/wp2/q7/q7_index.htm>. NoTIES password is required.

A new discussion group forum has been created to help promote interim discussion and drafting oftext. This forum is open to all, available at: <http://skene.org/q7>.

TD-016(Plen) (J. Skene, Tellabs) describes the relationships between Q7/15 and the IETF. Q7/15is developing Recommendation G.799.1 that describes the functions and characteristics of a voice



gateway used to interconnect GSTN and IP networks. The IETF, in co-operation with ITU-TSG16, is currently developing H.248/MGCP. This protocol is used to communicate between thevoice gateway and the media gateway controller. H.248 is now complete, but additional“packages” that describe how specific defined messages are sent through H.248 are continuallybeing developed. One example is a new package that allows control of signal processing functionsthat may be integrated into the G.799 gateway, such as echo cancellation and automatic levelcontrol. Additional packages may be needed. It is expected that liaison will be needed with theConfiguration Management with SNMP (snmpconf ) WG when the management interface for theG.799.1 gateway is specified. This section of the Recommendation is still under development.Similarly, Q7/15 will work with the Remote Network Monitoring (rmonmib) group to determine therequirements and nature of fault, configuration, and performance management monitoring.

TD-019(Plen) (J. Eaves, Tycom) contains information supplementary to TD-016(Plen); it providesthe text of the WG charters for three new IETF activities: IP over Optical (ipo), Common Controland Measurement Plane (ccamp), and IP over Resilient Packet Rings (iporpr).

Q8/15 WP2, Interaction Aspects of Signal Processing NetworkEquipment

H. Kullmann (Deutsche Telekom) is the Q8/15 Rapporteur. TD-017(WP2/15) is the agenda; TD-018(WP2/15) is the list of documents. TD-020(WP2/15) is the Q8/15 work program.

This meeting was the first meeting after the approval of Q8/15 at WTSA 2000. To organize thework within the question, an overview about the work within Q8/15 was given, and a work programwas discussed for the 2001 – 2004 ITU-T study period. It was agreed to develop a newRecommendation G.167.bis, Interaction aspects of signal processing network equipment, to expandG.167 to include interactions also between other SPNEs. The need for a revision ofRecommendation G.167 was recognized because G.167 currently covers only Section 6 that dealswith any interaction between terminal-based acoustic echo controllers and network-based signalprocessing equipment (e.g., echo cancelers, DCME). Responsibilities of the Sections 1-5 of G.167were taken over in P.340 of SG12. Contributions addressing interaction aspects of SPNEs wererequested.

Because of the overlap of study items between Q7/15 and Q8/15 (Items 6, 8, 9, and 10 of the Q7/15workplan), Q7 and Q8 agreed to discuss these items jointly in the future. An interim Q8/15meeting is planned for April to draft the new G.167.bis.

TD-019(WP2/15) (H. Kullmann, Deutsche Telekom, Rapporteur) is the text for Q8/15, Interactionaspects of signal processing network equipment. Signal processing network equipment (SPNE) isan integral part of communication networks. SG15 has developed Recommendations on circuitmultiplication, speech enhancement (network echo cancelers and automatic level control), andGSTN/IP gateway equipment. Q8/15 deals with the study of interoperability of SPNE betweendifferent SPNE and between SPNE and existing and/or new voice-band traffic technologies,including interactions between acoustic echo controllers and network equipment. Its main purposeis to ensure the correctness of Recommendations in the area of signal processing networkequipment, and to provide a discussion platform for interoperability and interaction concerns.Responsibility under this Question includes those signal processing recommendations not coveredby Questions 5, 6, and 7/15. TD-019(WP2/15) also outlines the study items, specific tasks, andrelationships of Q8/15.



Liaisons

TD-002(WP2/15) is a liaison from ITU-R WP4B providing comments on the liaison from ITU-TSG15 to ITU-T SG12 on the method for deciding on codec type and packet size. WP4B confirmstheir interest in the Q21/15 work in developing Recommendation G.799.1, which describes issuesassociated with voice over IP gateways. Noting that these gateways must select a preferred codeccombination and packet size, WP4B is interested in minimizing the delay in the terminals andgateways to preserve as much as possible for the transmission system. Many countries, includingthose that are only accessible via satellite, are looking to packet transmission techniques to squeezemore capacity out of their relatively narrow bandwidth satellite links; the flexibility of being able tohandle congestion by dropping back to a lower speed codec would be very desirable. On the issueof packet size, the extra overhead introduced by packetization should be minimized to optimizeusage on narrow bandwidth links, but not to the extent of adding too much delay. Finally, WP4Bnotes that the SG15 liaison did not mention the QoS control that might be exercised by thecustomer, and the probability that the customer’s request for a particular QoS will determine thechoice of codec.

TD-004(WP2/15) is a liaison from SG12 in response to the liaison from Q21/15 on the method fordeciding on codec type and packet size. SG12 is pleased to provide information to Q21/15 ontrade-offs between codec type, number of speech frames per IP packet, and delay; it notes that logicfor codec selection is the mandate of ITU-T SG16.

With respect to delay values for combination of codec and number of speech frames per packet,SG12 notes that it has just completed revisions to Recommendation G.114, One-way transmissiontime. Appendix I/G.114 includes many tables that address this issue. TD-004(WP2/15) includes acopy of a SG12 delayed contribution which might be useful in this context: D.117, “Someconsiderations regarding effectiveness, packet size, and delay for speech codecs in VoIP gatewaysand terminals” (U. Brunner, J. Pomy, Robert Bosch, Germany, Geneva, May 2000). SG12 notesthat Recommendation G.177 Section 7.4.1.1 provides general information on how to calculate delayfor a given combination of codec and packetization strategy.

Q8/15 discussed TD-002(WP2/15), and TD-004(WP2/15), regarding the selection of codec typesand packet size in IP gateways. Q7/15 also discussed TD-004(WP2/15) at the September Q7/15meeting in Munich; it was agreed to include the last paragraph of page 1 (below) into Section 3.3.1of draft Recommendation G.799.1:

The delay associated with codec processing and packetization should be kept as short aspossible. To accomplish this objective when G.729 or G.729A is used, two frames per packetshould be considered as the maximum packet size. Similarly, G.711 may be used with packetsizes of 10 ms (80 frames) or 20 ms (160 frames) to achieve this objective. Finally, whenG.723.1 is used, only one frame should be included in each packet. The 30 ms frame size ofG.723.1 results in speech collection and coding delay of at least 60 ms, contributing todifficulty of interactive communications.

TD-003(WP2/15) is a liaison from SG12 thanking SG15 for their liaison on RecommendationP.340, and for the information SG15 provided on the future of Recommendations G.167 (Acousticecho controllers, AEC) and G.168, Digital network echo cancelers. SG12 has Approved revisedRecommendation P.340, Transmission characteristics of hands-free telephones. SG12 added toSection 10.1 of Recommendation P.340 a reference to Recommendation G.168, Appendix I,Section I.6.6, with the following text:

NOTE: Interactions between terminal AEC and network signal processing equipment areconsidered in section I.6.6 of Appendix I of Recommendation G.168.

Q8/15 agreed to draft a liaison to SG12 to inform them of the new Recommendation G.167.bis.



TD-006(WP2/15) is a liaison from ITU-T SG16 addressing issues with Recommendation V.18text telephone transmission through network echo cancelers and issues with V.34 fax transmissionthrough network echo cancelers. Q8/15 agreed to send a liaison to SG16, to inform them of theresults of these tests. See report of Q6/15, above.

D.57 (B. Reeves, BT) reports on the performance of text telephones when used in connections withnetwork echo cancelers. It was discussed together with TD-006(WP2/15), the liaison from ITU-TSG16 addressing issues with Recommendation V.18 text telephone transmission through networkecho cancelers and issues with V.34 fax transmission through network echo cancelers. Q8/15agreed to add text to Test 14 in Recommendation G.168 (2002) to ensure that in the future echocanceler manufacturers and network operators will be reminded to test performance with V.18compatible text telephones. See report of Q6/15, above.

TD-008(WP2/15) is a liaison from ITU-T SG11/Q10 in response to the SG16 liaison discussingecho control in VoIP. This was presented for information; no action was proposed. Q10/11 pointsout the following:

Echo control logic, as described in Q.115 (Logic for the control of echo control devices) inconjunction with an Implementers Guide, should be part of the call feature functions of any MGC.This will allow for the optimum placement of the echo control devices and will avoid cascading ofecho control devices. The echo control signaling information conveyed in the signaling does notindicate which type of echo control device may have been provided in the PSTN/ISDN; therefore, ingeneral, cascading of echo control devices should be avoided. Furthermore, in scenarios whereecho control devices are arranged in a pool, providing an additional echo control device would be awaste of resources.

Voice-band data calls originating at a POTS terminal are not necessarily recognized as such; noappropriate information is available from the access. They are therefore treated by call control asvoice calls. The network may provide echo control devices, if routing data in one or more networknodes indicates “long haul route” or if the propagation delay exceeds a threshold of 20 – 25 ms.It is the called-modem that, by sending the “answer/disabling tone,” disables only echosuppressors or both echo suppressors and echo cancelers, depending on the type ofanswer/disabling tone used.

TD-005(WP2/15) is a liaison from Q13/16 and Q14/16 in response to a SG15 liaison requestinginformation and guidance on the deployment and control of echo cancelers used in association withvoice over IP connections, which emanated from the January - February, 2000 Punta del Este WP2Rapporteurs meeting. Q13/16 and Q14/16 agree that H.248 can be used to provide the necessaryecho cancellation control; the required capability is included as part of the TDM package in H.248Annex E section E.13. They report that Q9/11 is modifying the detail of H.248 control of off-board signal processing equipment and will likely soon provide SG15 the details. An architecturalrefinement may arise in H.323 operation: H.248 messages may originate with the H.323 gatekeeperand pass to the H.323 gateway control (MGC) function for transmission to the H.323 gatewaymedia gateway (MG) function. H.323 Annex L (stimulus signaling) sets a precedent for such anarchitecture.

Q8/16 discussed TD-005(WP2/15). The diagram on page 2 of this liaison shows the Q.115(Logic for the control of echo control devices) logic process residing in the H.323 Gatekeeper,whereas in G.799.1 this function is shown as being in the MGC. Q7/15 discussed this documentat the September 2000 meeting in Munich (TD11(WP2/15), and sent a liaison to SG13 to ask theiradvice on where this function should be located. Q7/15 is not concerned with where Q.115 islocated; they would like to properly illustrate it in the documentation.



TD-007(WP2/15) is a reply from SG16 to the SG15 liaison regarding external reset of a speechcodec used together with a discontinuous transmission (DTX) mechanism in circuit multiplicationequipment. SG16 discussed the issue; they prefer the existence of a synchronous reset capabilityin CME using the G.728 algorithm. Aligning the internal status of the encoder and decoder ofG.728 using an external synchronous reset will benefit speech quality, particularly at the transientfrom silence to active speech when the codec is used under DTX condition in CME. SG16 expectsno negative effects on speech quality because of the synchronous reset for G.729 under DTXfunction in CME. SG16 intends to submit experimental results to SG15 showing the effect ofsynchronous reset on the speech quality for G.729.

Q8/15 agreed to send a liaison to SG16 to request formal input also on the usage of synchronousreset for G.729 codec. TD-007(WP2/15) was considered by Q8/15 to provide importantinformation about interaction aspects of signal processing network equipment.

Q8/15 discussed COM15-26, Results of echo return loss (ERL) measurements in European publicswitched telephone networks (Telia), and D.49, Hybrid measurements in France Telecom network.These contributions were presented for information. The discussion of COM15-26 raised thequestion of how can useful information easily be made available. It was agreed to insert a link onthe Q8/15 home page to give access to all important documents, and to add this document underthis link.

Q8/15 discussed D.40 (H. Kullmann, Deutsche Telekom), which shows that ADPCM coders in theecho path may influence convergence characteristics of an echo canceler, e.g., convergence speedand residual echo attenuation. Q8/15 saw this document as providing important information aboutinteraction aspects of signal processing network equipment. See also the Q6/15 report, above.

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SG15 WP1 & 2 Meeting Roster, February 5 – 9, 2001, Geneva

Peter Wery (Canada) SG15 ChairGastone Bonaventura (Italy) SG15 Vice-ChairHaruo Okamura (Japan) SG15 Vice-ChairStephen Trowbridge (US) SG15 Vice-ChairAndrew Nunn (UK) Chair, WP1/15Duncan Sparrell (USA) Chair, WP2/15

Austria Telekom Austria Helmut Fabian [email protected] Telekom Austria Gerhard Hadaier [email protected] Administrations Frank Van Der Putten [email protected] Alcatel Bell Michael Beck [email protected] Alcatel Bell François Fredricx [email protected] Alcatel Bell Peter Reusens [email protected] Alcatel Bell Edwin Ringoot [email protected] Alcatel Bell Danny Van Bruyssel [email protected] Alcatel Bell Ivo Van Gelder [email protected] Administrations Peter Wery [email protected] Administrations Silas Zhou [email protected] Alcatel Canada Charles Storry [email protected] Catena Technologies Andrew Deczky [email protected] Nortel Networks Dominique Ho [email protected] Administrations Yunzhi Chen [email protected] Administrations Gang Cheng [email protected] Administrations Ming Cheng [email protected] Administrations Yi Da HeChina Administrations Zeng Hui Liu [email protected] Administrations Qian Mao [email protected] Administrations Shunyao Ren [email protected] Administrations Junhua Wang [email protected] Administrations Leping Wei [email protected] Administrations Xiao Feng WuChina Administrations Yong Hong Xu [email protected] Administrations Shirong YangChina Administrations Yusen Yang [email protected] Administrations Cheng Liang Zhang Zcl.bupt.edu.cnDenmark Tele Danmark Arne Kyhn [email protected] Elisa Communications Seppo Tormala [email protected] Nokia Corporation Jouko Tormamen [email protected] Tellabs Oy Maurice Givens [email protected] Tellabs Oy Jerry Skene [email protected] France Telecom Renee Le Viol [email protected] France Telecom Hubert Mariotte [email protected] France Telecom Helene Quere [email protected] Administrations Lionel Guingo [email protected] Administrations Gilles Joncour [email protected] France Telecom Tayeb Ben Meriem [email protected] IBM Europe Sedat Oelcer [email protected] Administrations Reinhold Feigel [email protected] Administrations Hans L. Koffler [email protected] Administrations Harald Kullmann [email protected] Administrations Gunther Zedler [email protected]



Germany Alcatel SEL Günter Grüell [email protected] Alcatel SEL Volker Haegele [email protected] Alcatel SEL Hans J. Matt [email protected] Alcatel Sel Kerstin Skerra [email protected] Deutsche Telekom Andreas Templin [email protected] Infineon Technologies Dirk Daecke [email protected] Infineon Technologies Neal King [email protected] Siemens Juergen Heiles [email protected] Siemens Hagen Henniger [email protected] OTE George Bathas [email protected] OTE Panayiotis Verrios [email protected] Administrations Laszlo Barna [email protected] Administrations Ujjal Bose [email protected] Administrations Ajay Kumar Goyal [email protected] Administrations Ashok Gupta [email protected] Administrations Atul Gupta [email protected] Administrations Vijay Kumar [email protected] Sasken Comm. Jagadish Kumar Dasari [email protected] Administrations Erez Bashan [email protected] Administrations Idan Kaspit [email protected] Administrations Oleg Litvak [email protected] Administrations Thomas Maudoux [email protected] Administrations Ilan Sharfer [email protected] Administrations Eyal Shraga [email protected] Administrations Ronen Sommer [email protected] Administrations Moshe Topman [email protected] Tioga Technologies Yoram Malka [email protected] Administrations Sergio Cascelli [email protected] Administrations Roberto Flaiani [email protected] Alcatel Italia Giovanni Paoli [email protected] CSELT Marco De Bortoli [email protected] CSELT Pietro Di Vita [email protected] CSELT Antonio Manzalini [email protected] CSELT Rosaria Persico [email protected] CSELT Fabio Randone [email protected] Marconi Segio Lanzone [email protected] Marconi Mauro Molinari [email protected] Pirelli Cavie Sistemi Paolo Boero [email protected] STMicroelectronics Christophe Del Toso [email protected] Telecom Italia Gastone Bonaventura [email protected] Administrations Yoichi Maeda [email protected] Administrations Haruo Okamura [email protected] CLPAJ Masahiko Dazai [email protected] CLPAJ Ryuichi Sugizaki [email protected] CLPAJ Daiichiro Tanaka [email protected] DDI Yukio Horiuchi [email protected] DDI Hideaki Yamada [email protected] Fujitsu Kazuo Yamane [email protected] Fujitsu Haruo Yamashita [email protected] Fujitsu Shoji Yoshida [email protected] Hitachi Tohru Kazawa [email protected] Hitachi Masaki Ohira [email protected] Hitachi Yoichi Tsukioka [email protected]



Japan Matsushita ElectricIndustrial

Keiichi Tomita [email protected]

Japan Mitsubishi Electric Hirashi Ichibangase [email protected] Mitsubishi Electric Yushi Naito [email protected] Mitsubishi Electric Tetsuya Yokotani [email protected] NEC Shigekazu Harada [email protected] NEC Kurenai Murakami [email protected] NEC Hiroshi Okado [email protected] NEC Tsutomu Tajima [email protected] NTT Koji Kikushima [email protected] NTT Naohide Nagatsu [email protected] NTT Kazuhiro Oda [email protected] NTT Masaharu Ohashi [email protected] NTT Takako Sato [email protected] NTT Shigeru Tomita [email protected] NTT Masahito Tomizawa [email protected] Oki Electric Industry Satoru Karasawa [email protected] Oki Electric Industry Toshiaki Mukojima [email protected] Oki Electric Industry Toshio Nakamura [email protected] Oki Electric Industry Akihiro Takahashi [email protected] Sumitomo Electric

IndustriesMasami Ueda [email protected]

Japan Toshiba Takanao Amatsubo [email protected] Toshiba Hiroyuki Inamura [email protected] Korea Telecom Chae-Sub Lee [email protected] Administrations Lucio Adame [email protected] Administrations Viacheslav Biryukov [email protected] Administrations Dimitry Cherkesov [email protected] Administrations Dimitry MazurenkoRussia Rostelecom Alexandr Kushtuev [email protected] Arabia S.T.C. Ahmed Yamani [email protected] L.M. Ericsson Per-Erik Eriksson [email protected] L.M. Ericsson Anders Gavler [email protected] L.M. Ericsson Zere Ghebretensae [email protected] L.M. Ericsson Albin Johansson [email protected] L.M. Ericsson Jörgen Karlsson [email protected] L.M. Ericsson Tönu Trump [email protected] Telia Niklas Johansson [email protected] Administrations Rene Koch [email protected] Administrations Hassane Makki [email protected] ArabRepublic

Administrations Nabil Kisrawi

Thailand Administrations Damri AnopasUkraine Administrations Nikolai Biryukov [email protected] Administrations Viktor Katok [email protected] Acterna Peter Huckett [email protected] Administrations Mike Bexon [email protected] Administrations Andrew Nunn [email protected] Agilent Technologies Niall Brown [email protected] Agilent Technologies Walter Grieve [email protected] Agilent Technologies Jim McIntyre [email protected] BT John Cook [email protected] BT David Faulkner [email protected] BT Kevin Foster [email protected]



UK BT Keith James [email protected] BT Robert Reeves [email protected] Cable & Wireless Rodney Hamblion [email protected] Document Tech. Research

Lab. EuropeAlan Pugh [email protected]

UK Fujitsu Europe Martin Andrews [email protected] Fujitsu Europe Vincent Barker [email protected] Lucent Technologies John Magill [email protected] Nortel Networks (Europe) Leslie Humphrey [email protected] Tektronix UK Ermanno Moscheni [email protected] Virata Limited Bijit Halder [email protected] 3Com Joseph Mueller [email protected] 3Com Richard Stuart [email protected] Administrations Steven Blackwell [email protected] Administrations John Chen [email protected] Administrations Daun Langston [email protected] Administrations James E. Matthews [email protected] Administrations John McDonough [email protected] Administrations Stephen Miller [email protected] Administrations Ed Underwood [email protected] Administrations Benson Wang [email protected] Adtran Marc Kimpe [email protected] Advanced micro Devices Terry Cole [email protected] Alcatel USA Lane Moss [email protected] Analog Devices Vladimir Friedman [email protected] AT&T Deborah Brungard [email protected] AT&T Duncan Sparrell [email protected] Aware Aron Friedmann [email protected] Aware Patrick Kelliher [email protected] Aware Marcos Tzannes [email protected] Bell South Brian Ford [email protected] Broadcom Corp. Arthur CarlsonUSA Broadcom Corp. Stephen Palm [email protected] Broadcom Corp. Miguel Peeters [email protected] Centillium Comm. Syed Abbas [email protected] CIENA Corp. Rajender Razdan [email protected] CIENA Corp. Jerry Shrimpton [email protected] CIENA Corp. Alan Weissberger [email protected] Cisco Systems Jay Shah [email protected] Compaq Rabah Hamdi [email protected] Conexant Systems Les Brown [email protected] Conexant Systems Keith T. Chu [email protected] Conexant Systems Jack Douglass [email protected] Conexant Systems George Eisler [email protected] Conexant Systems Shrenik Patravali [email protected] Copper Mountain Networks Rick O’Connell [email protected] Corning Robert S. Carlisle [email protected] Corning Thomas A. Hanson [email protected] Corning Felix P. Kapron [email protected] Ditech Comm. Thomas Oshidari [email protected] ESS Technology Jordan Cookman [email protected] Fujitsu Network Comm. Emir Catovic [email protected] GlobeSpan Massimo Sorbara [email protected] Intel Chris Hansen [email protected]



USA Intel Barry O’Mahony [email protected] Legerity Vijay Davar [email protected] Lucent Technologies Bernard Eichenbaum [email protected] Lucent Technologies Geoffrey Garner [email protected] Lucent Technologies Nevin Jones [email protected] Lucent Technologies Kam Lam [email protected] Lucent Technologies Harry Mildonian [email protected] Lucent Technologies Steve Strauss [email protected] Lucent Technologies Stephen Trowbridge [email protected] Motorola Bernard Dugerdil [email protected] NEC USA Donovan Nak [email protected] Next Level Comm. Todd Pett [email protected] Nortel Networks Astrid Lozano [email protected] Nortel Networks Michael Mayer MgmWnortelnetworks.comUSA Nortel Networks Ludovico Prattico [email protected] Paradyne Corporation William Pechey [email protected] PC-TEL Khashayar Mirfakhraei [email protected] Quantum Bridge Comm. Frank Effenberger [email protected] SBC Communications John Erickson [email protected] SBC Communications Renee EstesUSA SBC Communications Kent McCammon [email protected] SBC Communications B. Sambasivan [email protected] SBC Communications Tom Starr [email protected] Sprint Corporation Mark Jones [email protected] Telcordia Tech. Tobey Trygar [email protected] Terawave Comm. Siddhartha Devadhar [email protected] Terawave Comm. Christophe Pfistner [email protected] Texas Instruments James Carlo [email protected] Texas Instruments Tom Harley [email protected] TyCom John Eaves [email protected] VoCal Technologies Juan Alberto Torres [email protected] WorldCom Robert Born [email protected] BDT Fidelia AkpoITU TSB Paolo Rosa [email protected]

EUTELSAT Malcolm Jones [email protected]

ACRONYM DEFINITIONS

3GPP Third Generation Partnership Project (ETSI)AAP Alternative Approval ProceduresACELP Adaptive CELPADPCM Adaptive Differential PCMADSL Asymmetric Digital Subscriber LineAM Amplitude ModulationAPON ATM PONATM Asynchronous Transfer ModeATU-C ADSL Transceiver Unit - Central Office EndATU-R ADSL Transceiver Unit - Remote Terminal EndB-ISDN Broadband-ISDNBC Bearer ChannelBCC Basic Control ChannelBPON Broadband Passive Optical NetworkCAS Channel Associated SignalingCC Control Channel



CCS Common Channel SignalingCCT Channel Check TestCED Called Station Identification (T.30)CELP Code Excited Linear PredictionCISPR International Special Committee on Radio InterferenceCME Circuit Multiplication EquipmentCPE Customer Premise EquipmentCRC Cyclic Redundancy CodeCS-ACELP Conjugate Structure ACELPDCE Data Circuit terminating EquipmentDCME Digital Circuit Multiplication EquipmentDMT Discrete MultiToneDSI Digital Speech InterpolationDSL Digital Subscriber LineDTMF Dual Tone Multi FrequencyDTX Discontinuous TransmissionECC Expanded Control ChannelEDH Electronic Document HandlingEDT European Deaf TelephoneEMC ElectroMagnetic CompatibilityERL Echo Return LossETSI European Telecommunications Standards InstituteEXOR Exclusive ORFEC Forward Error CorrectionFEXT Far End Cross TalkFSAN Full Service Access NetworksGSTN General Switched Telephone Network (i.e., PSTN)HDLC High level Data Link ControlHDSL High-rate Digital Subscriber LineIEC International Electrotechnical CommissionIEEE Institute of Electrical and Electronic EngineersIETF Internet Engineering Task ForceIF Isolation FunctionIMT International Mobile Telecommunications (IMT-2000)IP Internet ProtocolISDN Integrated Services Digital NetworkIT Intermediate TrunkITU-R ITU Radiocommunications SectorITU-T ITU Telecommunications SectorLD-CELP Low Delay CELPLMS Loop Management SystemLRE Low bit Rate EncodingMCM Multi-Carrier ModulationMF Multi-tone FrequencyMGC Media Gateway ControllerMGCP Media Gateway Control ProtocolNEXT Near End Cross TalkNLP Non-Linear ProcessorNTR Network Timing ReferenceOFTEL British Office of TelecommunicationsOLT Optical Line TerminationONT Optical Network TerminationPCM Pulse Code ModulationPHY Physical Layer



PLOAM Physical Layer Operations, Administrations and MaintenancePMD Physical Media Dependent layerPMS-TC Physical media Specific - Transmission ConvergencePN Project Number (TIA)PNT Phone-line Network TransceiverPON Passive Optical NetworkPOTS Plain Old Telephone ServicePRBS Pseudo-Random Bit SequencePSD Power Spectral DensityQAM Quadrature Amplitude ModulationRF Radio FrequencyRFI Radio Frequency InterferenceRTP Real Time Transport Protocol (IETF)S/N Signal-to-NoiseSCM Single-Carrier ModulationSCN Switched Circuit NetworkSG Study Group (ITU)SNMP Simple Network Management Protocol (IETF)SPNE Signal Processing Network EquipmentSS#5 Signaling System 5SSG Special Study Group (ITU)STM Synchronous Transmission ModeSTU-R SHDSL Transceiver Unit - Remote Terminal EndTBD To be DeterminedTC Transmission Convergence LayerT-CONT Traffic Container (G.983.dba)TDM Time Division MultiplexTIA Telecommunications Industry AssociationTIGIN Transport Network Equipment for Interconnecting GSTN and IP NetworksTMN Telecommunication Management NetworkTPS-TC Transport Protocol Specific-Transmission ConvergenceTS Time Slot (Q6/15)TSAG Telecommunication Standardization Advisory Group (ITU)UMTS Universal Mobile Telecommunications SystemVAME Voice on ATM Multiplication EquipmentVBD Voice Band DataVDSL Very high speed DSLVED Voice Enhancement DevicesVoDSL Voice over DSLVoIP Voice Over Internet ProtocolWDM Wavelength Division MultiplexingWG Working GroupWTSA World Telecommunications Standardization Assembly (ITU)xDSL all the different Digital Subscriber Line technology

Visit the CSR Web Pages: http://www.csrstds.comThe Web Pages include an on-line store (order subscriptions and reports), an updatedTelecom Acronym Definitions list, updated meeting schedules, background material ontelecom standards and CSR (the company), data sheets on both CSR technical journals, andmore.



COMMUNICATIONS STANDARDS REVIEW COPYRIGHT POLICY

Copying of individual articles/reports for distribution within an organization is not permitted, unlessthe user holds a multiple copy license from CSR. The single user electronic version may bemounted on a server whose access is restricted both to a single organization and to one user at atime. You are welcome to forward your single user electronic copy (deleting it on your system) toanother user in your organization. CSR offers an Intranet subscription which permits unlimitedcopies to the subscribing organization.

Year 2001 Standards Committee Meeting SchedulesPlease see the updated calendar at http://www.csrstds.com/mtgs.html.

Communications Standards Reviewregularly covers the following committee meetings:

TIA TR-30 Data Transmission Systems &Equipment

TR-41 User Premises Telephone EquipmentRequirements

ITU-T SG15 WP1 Network AccessSG15 WP2 Network Signal ProcessingSG16 Multimedia

ETSI AT Access and TerminalsTIPHON Voice over InternetTM6 Transmission & Multiplexing

DSL Forum xDSL, Access Technologies

Communications Standards Review (ISSN 1064-3907) reports are published within days after the relatedstandards meetings. Publisher: Elaine J. Baskin, Ph.D. Technical Editor: Ken Krechmer. Subscription Manager:Denise Hylen Lai. Copyright © 2001, Communications Standards Review. All rights reserved. Subscriptions:$795.00 per year worldwide, electronic format; $995.00 paper format. Corporate Intranet subscriptions (Corporatelicense for unlimited copies) are $2,150.00. Submit articles for consideration to: Communications StandardsReview, 757 Greer Road, Palo Alto, CA 94303-3024 USA. Tel: +1-650-856-9018. Fax: +1-650-856-6591.e-mail: [email protected]. Web: http://www.csrstds.com. 12693