1、 International Telecommunication Union ITU-T G.991.2TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Amendment 2(02/2005) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Access networks Single-pair high-speed digital subscriber line (SHD
2、SL) transceivers Amendment 2 ITU-T Recommendation G.991.2 (2003) Amendment 2 ITU-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-TRANSMISSION SYS
3、TEMS 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 RADIOTELEPHONY AN
4、D LINE TELEPHONY G.450G.499 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 G.910G.919 Digital sections at hierarchical b
5、it 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 section and digital transmission systems for custome
6、r 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 GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DIGIT
7、AL 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.991.2 (2003)/Amd.2 (02/2005) i ITU-T Recommendation G.991.2 Single-pair high-speed digital subscriber line (SHDSL) transceivers Amendment 2 Summary T
8、he following text reflects the agreed modification for a second amendment to ITU-T Rec. G.991.2 (2003). The text modifications are shown with revision marks. Source Amendment 2 to ITU-T Recommendation G.991.2 (2003) was approved on 22 February 2005 by ITU-T Study Group 15 (2005-2008) under the ITU-T
9、 Recommendation A.8 procedure. ii ITU-T Rec. G.991.2 (2003)/Amd.2 (02/2005) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications. The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-
10、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 every four years, establishes the topics for stud
11、y 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 purview, the necessary standards are prepared on a c
12、ollaborative 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. Compliance with this Recommendation is voluntary. However, the Recommendation may contain c
13、ertain mandatory provisions (to ensure e.g. interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requir
14、ements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right
15、. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual
16、property, protected by patents, which may be required to implement this Recommendation. However, implementors are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database. ITU 2005 All rights reserved. No part of this publicatio
17、n may be reproduced, by any means whatsoever, without the prior written permission of ITU. ITU-T Rec. G.991.2 (2003)/Amd.2 (02/2005) iii CONTENTS Page 1) Modifications to clause 2, References, and to Bibliography in Appendix V . 1 2) Addition to clause 3.2 “Abbreviations“. 1 3) Modification to claus
18、e 6.1.5 “Power backoff“. 1 4) Modification to clause 6.3.1 . 1 5) Modification to clause 6.3.2.1 “Signal Pri“ 2 6) Modification to clause 6.3.2.2 “Signal Pci“ 2 7) Modification to clause 6.4.3 “G.994.1 transactions“ . 2 8) Modification to clause 11.5 “Signal transfer delay“ 2 9) Modification to clau
19、se A.5.2 “Return loss“ . 2 10) New clause B.2.4 “Test loop measurement accuracy“ 3 11) Modifications to clause B.3.3.2.1 “Differential-mode noise calibration“ . 4 12) Edit to clause B.3.4 “Performance test procedure“ 5 13) New text for clause B.3.5.3.7 “Impulse noise generator G7“ . 5 14) Modificati
20、on to clause B.5.2 “Return loss“ . 7 15) Modifications to clause B.5.3.2 “Power feeding of the STU-R“. 7 16) Modification to clause B.5.3.3 “Power feeding of the interface for narrow-band services“ 7 17) Modification to clause B.5.3.4 “Feeding power from the STU-C“ . 8 18) Modification to clause B.5
21、.3.5 “Power available at the STU-R“ 8 19) New clauses B.5.3.6 “DC and low frequency AC termination of STU-R“ and B.5.3.7 “Wetting current“ 9 20) Modifications to clause D.3 “Symbol rates“ 11 21) Modification to clause D.4 “PSD masks“ 11 22) Modifications to clauses E.8.7, E.8.8 and E.8.9 . 12 23) Mo
22、difications to clause F.3. 21 24) Text for new Annex G 22 ITU-T Rec. G.991.2 (2003)/Amd.2 (02/2005) 1 ITU-T Recommendation G.991.2 Single-pair high-speed digital subscriber line (SHDSL) transceivers Amendment 2 1) Modifications to clause 2, References, and to Bibliography in Appendix V Add the follo
23、wing reference to the list in clause 2: 12 ITU-T Recommendation I.430 (1995), Basic user-network interface Layer 1 specification. Add the following references to the Bibliography in Appendix V: B17 ETSI TBR 021 (1998-01), Terminal Equipment (TE); Attachment requirements for pan-European approval for
24、 connection to the analogue Public Switched Telephone Networks (PSTNs) of TE (excluding TE supporting the voice telephony service) in which network addressing, if provided, is by means of Dual Tone Multi Frequency (DTMF) signalling. B18 ETSI EN 300 012-1 V1.2.2 (2000-05), Integrated Services Digital
25、 Network (ISDN); Basic User-Network Interface (UNI); Part 1: Layer 1 specification. B19 ETSI EN 300 001 V1.5.1 (1998-10), Attachments to the Public Switched Telephone Network (PSTN); General technical requirements for equipment connected to an analogue subscriber interface in the PSTN. B20 ETSI EG 2
26、01 185 V1.1.1 (1999-02), Terminal support interface for harmonized analogue PSTN terminals. 2) Addition to clause 3.2 “Abbreviations“ Insert the following items to the Abbreviations list in clause 3.2: BRA Basic Rate Access e-SHDSL Enhanced SHDSL 3) Modification to clause 6.1.5 “Power backoff“ Add t
27、he following text to the end of clause 6.1.5 after Table 6-2: In the four-wire mode or M-pair mode, power backoff value PBO-1 shall be assigned to the pair on which the final G.994.1 transaction is conducted. Power backoff value PBO-2 shall be assigned to the remaining pair or pairs. 4) Modification
28、 to clause 6.3.1 Add the following Note at the end of clause 6.3.1: NOTE For 3 and 4 pairs, the current G.994.1 Annex B method of doing transactions on only one pair has some shortcomings when different parameter values, such as for PBO, might be required on each pair. 2 ITU-T Rec. G.991.2 (2003)/Am
29、d.2 (02/2005) 5) Modification to clause 6.3.2.1 “Signal Pri“ In the last paragraph of clause 6.3.2.1, add new text as follows: In the optional M-pair mode, Prishall be sent in parallel on all wire pairs. The assignment of power backoff values in 4-wire/M-pair mode shall be as specified in 6.1.5. 6)
30、Modification to clause 6.3.2.2 “Signal Pci“ In the last paragraph of clause 6.3.2.2, add new text as follows: In the optional M-pair mode, Pcishall be sent in parallel on all wire pairs. The assignment of power backoff values in 4-wire/M-pair mode shall be as specified in 6.1.5. 7) Modification to c
31、lause 6.4.3 “G.994.1 transactions“ Insert the following new paragraph prior to the last paragraph in clause 6.4.3: The assignment of power backoff values in 4-wire/M-pair mode shall be as specified in 6.1.5. 8) Modification to clause 11.5 “Signal transfer delay“ Add the following new paragraph to th
32、e end of the text in clause 11.5: The STU shall be capable of providing PMD-layer one-way, single-span latency of 500 s or less for user data rates of 1.5 Mbit/s and above, and 1.25 ms or less for user data rates below 1.5 Mbit/s as measured between the and interfaces. M-pair (more than one pair) op
33、eration shall add no more than 0.25 ms to the single span latency. 9) Modification to clause A.5.2 “Return loss“ Revise the text in clause A.5.2 to read as follows: A.5.2 Return loss For devices supporting Annex A functionality, return loss shall be specified based on the methodology of 11.3 and the
34、 limitations of Figure 11-6. The following definitions shall be applied to the quantities shown in Figure 11-6: RLMIN= 12 dB f0= 12.56 kHz f1= 50 kHz f2= fsym/2 f3= 1.99fsymwhere fsymis the symbol rate. For all Annex F symbol rates greater than 770.67 ksymbol/s, the minimum return-loss requirement s
35、hall be identical to the one defined for 770.67 ksymbol/s. The leakage inductance of the line transformer is not a function of the symbol rate. The limitation of the return-loss requirement does not change the performance targets. ITU-T Rec. G.991.2 (2003)/Amd.2 (02/2005) 3 10) New clause B.2.4 “Tes
36、t loop measurement accuracy“ Add new clause B.2.4 as follows: B.2.4 Test loop measurement accuracy The different cable sections of the test loops are specified by two-port cable models that represent real twisted pair cables. Cable simulators as well as real cables can be used to construct these tes
37、t loops. The associated models and line constants are specified in Appendix II. The characteristics of each test loop, including those with cascaded sections, shall approximate the models within a specified accuracy. This accuracy specification does not apply to the individual sections. The magnitud
38、e of the test loop insertion loss shall approximate the insertion loss of the specified models within (0.4 dB + 5% of insertion loss) on a dB scale, up to a maximum of 2.1 dB, between F1 and F2, where F1 and F2 are given in Table B.2a. The Mean Error (ME) of the test loop insertion loss shall be les
39、s than 0.3 dB, and at the same time the Mean Absolute Error (MAE) shall be less than 1.5 dB, between F1 and F2 for transmission in one direction for SHDSL, where F1 and F2 are given in Table B.2a. The Mean Error (ME) of the test loop insertion loss shall be less than (for further study), and at the
40、same time the Mean Absolute Error (MAE) shall be less than (for further study), between F1 and F2 for transmission in one direction for Enhanced SHDSL, where F1 and F2 are given in Table B.2a. To verify compliance with these ME and MAE requirements, the simulated loop shall be measured over the freq
41、uency band from Frequency 1 to Frequency 2 (F1 to F2), where F1 shall be the lowest frequency in the transmission band and F2 shall be the frequency at which the nominal loop attenuation reaches a value at which no signal can be received, or the upper transmission frequency, (as defined in Table B.2
42、a) whichever is lower. Measurements shall be made at N frequencies, separated by equal frequency increments of not more than 10 kHz. Table B.2a/G.991.2 Measurement frequency boundaries F1 F2 SHDSL 1 kHz Fsym e-SHDSL 1 kHz TBD The ME and MAE of the measured channel attenuation values in dB, relative
43、to the theoretical loop attenuation values in dB, shall be calculated for the N points measured. Theoretical values of loop attenuation shall be calculated using the RLGC parameters in Appendix II assuming source and load impedances of RVas defined in B.3.3.2.1. ME is given by (Attenuation values in
44、 dB): ()NonlAttenuatiTheoreticanuationActualAtteNiii=1ME 4 ITU-T Rec. G.991.2 (2003)/Amd.2 (02/2005) MAE is given by (Attenuation values in dB): NonlAttenuatiTheoreticanuationActualAtteNiii=1ME The magnitude of the test-loop characteristic impedance shall approximate the characteristic impedance of
45、the specified models within 7% on a linear scale, between frequencies F1 and F2, as given in Table B.2a. The group delay of the test loop shall approximate the group delay of the specified cascaded models within 3% on a linear scale, between frequencies F1 and F2, as given in Table B.2a. The electri
46、cal lengths (insertion loss at specified test frequency) of the test loops, specified in B.2.3, are normative. If the physical length of a test loop implementation is such that electrical length is out of specification, its total physical length shall be adjusted accordingly to correct this error. T
47、his adjustment to the loop-insertion loss by scaling of the physical length should also be used to correct for extra attenuation caused by the noise-injection circuit. 11) Modifications to clause B.3.3.2.1 “Differential-mode noise calibration“ Amend the text in clause B.3.3.2.1 to read as follows: B
48、.3.3.2.1 Differential-mode noise calibration The differential-mode noise injection is calibrated using the configuration shown in Figure B.2b. During calibration the RX side of the noise injector is terminated by the design impedance RV(= 135 ) and the LX (Test Loop interface) side of the noise inje
49、ctor is terminated by an impedance ZLX. The noise levels given in B.3.5 specify the PSD dissipated in RVon the RX side when ZLXon the LX side is equal to the calibration impedance Zcal. The impedance Zcalis defined in Figure B.2c. Figure B.2b/G.991.2 Configuration for noise level calibration G.991.2AMD.2_FB-2C120 150 750 47 nF 150 nFFigure B.2c/G.991.2 Calibration impedance ZcalITU-T Rec. G.991.2 (2003)/Amd.2 (02/2005) 5 When calibrating
