1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T G.992.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 1(03/2003) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Splitterless asymmetric digital subscriber line (AD
2、SL) transceivers Amendment 1: Revised Annex C ITU-T Recommendation G.992.2 (1999) Amendment 1ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGUE CARRIER-
3、TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDINATION OF R
4、ADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TESTING EQUIPMENTS G.500G.599 TRANSMISSION MEDIA CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 General G.900G.909 Parameters for optical fibre cable systems
5、 G.910G.919 Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.959 Digital sectio
6、n and digital transmission systems for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979 Optical line systems for local and access networks G.980G.989 Access networks G.990G.999 QUALITY OF SERVICE AND PERFORMANCE G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.600
7、0G.6999 DIGITAL TERMINAL EQUIPMENTS G.7000G.7999 DIGITAL NETWORKS G.8000G.8999 For further details, please refer to the list of ITU-T Recommendations. ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) i ITU-T Recommendation G.992.2 Splitterless asymmetric digital subscriber line (ADSL) transceivers Amendmen
8、t 1 Revised Annex C Summary This Amendment 1 to ITU-T Rec. G.992.2 revises Annex C for improved robustness and extended reach. It includes the changes introduced by G.992.2 (1999) Corrigendum 1 (07/2002). Source Amendment 1 to ITU-T Recommendation G.992.2 (1999) was prepared by ITU-T Study Group 15
9、(2001-2004) and approved under the WTSA Resolution 1 procedure on 16 March 2003. ii ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardizatio
10、n Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets
11、 every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts pu
12、rview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. INTELLECTUAL PROPERTY RIGHTS ITU draws at
13、tention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or oth
14、ers outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent th
15、e latest information and are therefore strongly urged to consult the TSB patent database. ITU 2003 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) iii CONTENTS Page C.1
16、 Scope 1 C.2 Definitions and abbreviations. 1 C.3 Reference models . 2 C.4 Operating modes (new) 6 C.5 ATU interfaces . 7 C.6 ATU functional characteristics (pertains to clause 7) 7 C.7 aoc on-line adaptation and reconfiguration (pertains to clause 9) 14 C.8 In-service performance monitoring and sur
17、veillance (pertains to clause 10). 15 C.9 Initialization 16 C.10 Fast retraining (supplements clause 12) . 36 C.11 Power management (pertains to clause 13) 41 Appendix IV Example Overlapped PSD Masks for use in a TCM-ISDN crosstalk environment 41 ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) 1 ITU-T Rec
18、ommendation G.992.2 Splitterless asymmetric digital subscriber line (ADSL) transceivers Amendment 1 Revised Annex C ADSL above POTS co-existing in the same binder as TCM-ISDN DSL C.1 Scope This annex describes those specifications that are unique to an ADSL system co-existing in the same binder as T
19、CM-ISDN as defined in Appendix III/G.961. The subclauses in this annex provide the additions and modifications to the corresponding clauses in the main body. The modifications described in this annex provide a performance improvement over the Splitterless ADSL system specified in main body in an env
20、ironment co-existing with TCM-ISDN. It is preferred that ADSL system implementing this annex also implements the main body. This annex defines several optional operating modes or “profiles“, negotiable through G.994.1, to allow limited independent control of: FEXT and NEXT period transmission in bot
21、h upstream and downstream directions overlapped and non-overlapped spectrum downstream during FEXT and NEXT periods These new optional profiles (defined in C.4 as Profiles 1 to 6) offer improved robustness and extended reach compared to the previously defined operating modes. NOTE References to figu
22、res or tables of Appendix IV will be defined when Appendix IV is made available. C.2 Definitions and abbreviations C.2.1 Definitions C.2.1.1 Dual Bitmap: The Dual Bitmap method has dual bit rates under the FEXT and NEXT noise from TCM-ISDN. C.2.1.2 FEXT Bitmap: Similar to the Dual Bitmap method; how
23、ever, transmission only occurs during FEXT noise from TCM-ISDN. C.2.1.3 Hyperframe: Five Superframes structure which synchronized TTR. C.2.1.4 Bitmap-FR: ATU-C transmitter bitmap under TCM-ISDN FEXT noise generated at ATU-R. C.2.1.5 Bitmap-NR: ATU-C transmitter bitmap under TCM-ISDN NEXT noise gener
24、ated at ATU-R. C.2.1.6 Bitmap-FC: ATU-R transmitter bitmap under TCM-ISDN FEXT noise generated at ATU-C. C.2.1.7 Bitmap-NC: ATU-R transmitter bitmap under TCM-ISDN NEXT noise generated at ATU-C. C.2.1.8 FEXTRduration: TCM-ISDN FEXT duration at ATU-R estimated by the ATU-C. 2 ITU-T Rec. G.992.2 (1999
25、)/Amd.1 (03/2003) C.2.1.9 NEXTRduration: TCM-ISDN NEXT duration at ATU-R estimated by the ATU-C. C.2.1.10 FEXTCduration: TCM-ISDN FEXT duration at ATU-C estimated by the ATU-R. C.2.1.11 NEXTCduration: TCM-SDN NEXT duration at ATU-C estimated by the ATU-R. C.2.1.12 FEXTRsymbol: DMT symbol transmitted
26、 by ATU-C during TCM-ISDN FEXT. C.2.1.13 NEXTRsymbol: DMT symbol transmitted by ATU-C during TCM-ISDN NEXT. C.2.1.14 FEXTCsymbol: DMT symbol transmitted by ATU-R during TCM-ISDN FEXT. C.2.1.15 NEXTCsymbol: DMT symbol transmitted by ATU-R during TCM-ISDN NEXT. C.2.1.16 NSWF: Sliding window frame coun
27、ter. C.2.2 Abbreviations TTR TCM- ISDN Timing Reference TTRCTiming Reference used in ATU-C TTRRTiming Reference used in ATU-R UI Unit Interval C.3 Reference models C.3.1 ATU-C transmitter reference model (replaces figure in 4.2) G.992.2_FC.1ATM0NTROAMTTRCell TCAS0Mux/synccontrolcrcscramandFECInter-l
28、eaverRateconverterNaturaltoneorderingConstel-lationencoderandgainscalingIDFTOutputparallel/serialbufferV-CMuxdata frameFEC outputdata frameCABConstellation encoderinput data framei = 1 to 127Reference pointsDAC and analogprocessingU-CNOTE The TTR may be generated in the ATU-C without being provided
29、from the V-C reference point TCM-ISDN clock.n = 1n = 0240254255ZiFigure C.1/G.992.2 ATU-C transmitter reference model for ATM transport ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) 3 C.3.2 ATU-R transmitter reference model (replaces figure in 4.2) G.922.2_FC.2ZiATM0OAMCell TCLS0Mux/synccontrolcrcscrama
30、ndFECInter-leaverRateconverterNaturaltoneorderingConstel-lationencoderandgainscalingIDFTOutputparallel/serialbufferMuxdata frameFEC outputdata frameCA BConstellation encoderinput data framei = 1 to 31Reference pointsDAC and analogprocessingU-RT-RTTRRNOTE The TTRRshall be generated in the ATU-R from
31、the received TTRC, and shall be locked to 690 periods of upstream sampling clock (276 kHz).n = 1n = 0596263Figure C.2/G.992.2 ATU-R transmitter reference model for ATM transport 4 ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) C.3.3 ATU transmitter timing model (new) C.3.3.1 TCM-ISDN crosstalk timing mod
32、el (new) Figure C.3 shows the timing chart of the crosstalk from TCM-ISDN. G.992.2_FC.3transmit ISDNFrame FrameFrame Frametransmit ISDNreceive ISDNFEXTRand NEXTRare estimated by the ATU-Creceive ISDN1 UI = 3.125 s 6-7.5 UIFEXTCand NEXTCare estimated by the ATU-R0 propagation delay 18.5 UI 0 propagat
33、ion delay 16 UI ReceivedTTRCTTR TCM-ISDN Timing referenceTTRCTiming reference used in ATU-CReceived TTRCReceived TTRCat ATU-RTTRRTiming reference used in ATU-RSC 55 0.9058 s: Offset from TTR to TTRCSR42 0.9058 s: Offset from received TTRCto TTRR ATU-C TxATU-R TxCORTTTRFEXTRNEXTRNEXTCFEXTC377 UI377 U
34、ISCSRTTRCTTRRFigure C.3/G.992.2 Timing chart of the TCM-ISDN cross-talk The data stream of TCM-ISDN transmitted in a TTR period. The TCM-ISDN CO transmits the symbols in the first half of the TTR period and the TCM-ISDN RT transmits in the second half of the TTR period. The ATU-C receives NEXT noise
35、 from ISDN in the first half of the TTR period and FEXT noise from ISDN in the second half of the TTR period. On the other hand, the ATU-R receives FEXT noise from the TCM-ISDN in the first half of the TTR period and NEXT noise from the ISDN in the second half of the TTR period. ITU-T Rec. G.992.2 (
36、1999)/Amd.1 (03/2003) 5 As defined in C.6.2.2 and in C.9, the ATU-C shall estimate the FEXTRand NEXTRduration at ATU-R, and ATU-R shall estimate FEXTCand NEXTCduration at ATU-C taking propagation delay on the subscriber line into consideration. The ATU-C shall transmit any symbol by synchronizing wi
37、th the TTRC. The ATU-R shall transmit any symbol by synchronizing with the TTRRgenerated from received TTRC. C.3.3.2 Sliding Window (new) Figure C.4 shows the timing chart of the downstream transmission. G.992.2_FC.4CrosstalkperiodATU-CTx frameFEXTRsymbolNEXTRsymbolSliding WindowHyperframe = 345 sym
38、bolsTTRC(400 Hz)SWBFEXTRNEXTRFEXTR FEXTRNEXTRFEXTRFigure C.4/G.992.2 Sliding Window The “Sliding Window“ operation defines the procedures to transmit symbols under the crosstalk noise environment synchronized to the period of the TTR. The FEXTC/Rsymbol represents the symbol completely inside the FEX
39、TC/Rduration. The NEXTC/Rsymbol represents the symbol containing any NEXTC/Rduration. Thus, there are more NEXTC/Rsymbols than FEXTC/Rsymbols. The ATU-C decides which transmission symbol is a FEXTRor NEXTRsymbol according to the Sliding Window and transmits it with the corresponding bit table. Simil
40、arly, ATU-R decides which transmission symbol is a FEXTCor NEXTCand transmits it with the corresponding bit table. Although the phase of the Sliding Window is asynchronous with the TTRC/R, the pattern is fixed to the 345 frames of the hyperframe (see C.6.2.2). C.3.3.3 ATU-C symbol synchronization to
41、 TTRC(new) The time duration of 345 symbols is equal to 34 cycles of TTRC(or 32 cycles of TTRCfor symbols without a cyclic prefix). This implies a PLL lock at the ATU-R. C.3.3.4 Dual Bitmap switching (new) The ATU-C transmits FEXTRsymbols using Bitmap-FR(in FEXTRduration), and transmits NEXTRsymbols
42、 using Bitmap-NR(in NEXTRduration) according to the result of initialization. The ATU-R transmits FEXTCsymbols using Bitmap-FC(in FEXTCduration), and transmits NEXTCsymbols using Bitmap-NC(in NEXTCduration) in the same manner. The ATU-C shall have the capability to disable Bitmap-NCand Bitmap-NRtran
43、smission during NEXTC/R(see Table 11-i/G.994.1 C.6.7), In this case, the ATU-C shall transmit only the pilot tone as NEXTRsymbol, and ATU-R shall transmit silence as the NEXTCsymbol (see C.5.5 and C.5.7). 6 ITU-T Rec. G.992.2 (1999)/Amd.1 (03/2003) During FEXT Bitmap mode, the ATU-C shall transmit o
44、nly the pilot tone as NEXTRsymbol As an option, an ATU-C may have the ability to enable or disable Bitmap-NCindependently of Bitmap-NR. This is controlled by way of the profiles negotiated through G.994.1. C.3.3.5 Loop timing at ATU-R (new) The phase relation between received symbol and transmitted
45、symbol of ATU-R at reference point U-R shall meet the phase tolerances as shown in Figure C.5. G.992.2_FC.5(point U-R)ATU-R receiveDMT symbolATU-R transmitDMT symbol4.5 s + SRFigure C.5/G.992.2 Loop timing for ATU-R C.4x Operating modes (new) The following profiles are defined to support independent
46、 control of FEXT and NEXT bitmaps in the upstream and downstream direction, as well as independent control of the downstream spectrum for each downstream bitmap: Profile 1 For Profile 1, upstream transmission only uses Bitmap-FC, and downstream transmission only uses Bitmap-FRwith non-overlapped spe
47、ctrum. Profile 2 For Profile 2, upstream transmission uses both Bitmap-FCand Bitmap-NC, and downstream transmission uses both Bitmap-FRand Bitmap-NR. Non-overlapped spectrum is used with both downstream bitmaps. Profile 3 For Profile 3, upstream transmission only uses Bitmap-FC, and downstream trans
48、mission only uses Bitmap-FRwith overlapped spectrum. An example of a downstream PSD mask for this operating mode is shown in Figure IV.3. Profile 4 For Profile 4, upstream transmission uses both Bitmap-FCand Bitmap-NC, and downstream transmission uses both Bitmap-FRand Bitmap-NR. Overlapped spectrum
49、 is used with both downstream bitmaps. Profile 5 For Profile 5, upstream transmission only uses Bitmap-FC, and downstream transmission uses both Bitmap-FRand Bitmap-NR. Non-overlapped spectrum is used with Bitmap-NR, and overlapped spectrum is used with Bitmap-FR. An example of a downstream PSD mask for use with Bitmap-NRis shown in Figure IV.1 and described in Table IV.1 in Appendix IV. An example of a downstream PSD mask for use with Bitmap-FRis shown in Figure IV.2 and described in Table IV.2 in Appendix
