1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T G.9701 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 4 (12/2017) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Access networks Metallic access networks Fast Access to Subscriber Termin
2、als (G.fast) Physical layer specification Corrigendum 4 Recommendation ITU-T G.9701 (2014) Corrigendum 4 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 ANALO
3、GUE CARRIER-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 COORD
4、INATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND U
5、SER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 Metallic access networks G.9700G.9799 Optical line systems for local and access networks G.9800G.9
6、899 In premises networks G.9900G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.9701 (2014)/Cor.4 (12/2017) i Recommendation ITU-T G.9701 Fast Access to Subscriber Terminals (G.fast) Physical layer specification Corrigendum 4 Summary Corrigendum 4 to Recomm
7、endation ITU-T G.9701 (2014) adds several clarifications, and fixes various errors and inconsistencies. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T G.9701 2014-12-05 15 11.1002/1000/12090 1.1 ITU-T G.9701 (2014) Cor. 1 2015-11-22 15 11.1002/1000/12541 1.2 ITU-T G.9701 (2
8、014) Cor. 2 2016-05-07 15 11.1002/1000/12817 1.3 ITU-T G.9701 (2014) Amd. 1 2016-05-07 15 11.1002/1000/12542 1.4 ITU-T G.9701 (2014) Amd. 2 2016-07-22 15 11.1002/1000/12816 1.5 ITU-T G.9701 (2014) Cor. 3 2017-04-06 15 11.1002/1000/13069 1.6 ITU-T G.9701 (2014) Amd. 3 2017-04-06 15 11.1002/1000/13068
9、 1.7 ITU-T G.9701 (2014) Cor. 4 2017-12-07 15 11.1002/1000/13332 1.8 ITU-T G.9701 (2014) Amd. 4 2017-12-07 15 11.1002/1000/13331 * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/
10、handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T G.9701 (2014)/Cor.4 (12/2017) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standar
11、dization 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), whic
12、h meets 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 IT
13、U-Ts purview, 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. Compliance with this Recommendatio
14、n is voluntary. However, the Recommendation may contain certain 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 “mu
15、st“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation ma
16、y 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 others outside of the Recommendation development process. As of the date of approval of thi
17、s Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database
18、 at http:/www.itu.int/ITU-T/ipr/. ITU 2018 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.9701 (2014)/Cor.4 (12/2017) iii Table of Contents Page 1) Clause 3.2.30 1 2) Clause 10.2.2.2 . 1 3) Clause
19、 10.3.2.3.1 1 4) Clause 10.3.2.5.2 3 5) Clause 11.2.2.10 . 4 6) Clause 11.3.1.1 . 5 7) Clause 11.3.1.3 . 5 8) Clause 11.3.1.4 . 6 9) Clause 11.4.1.2.1 6 10) Clause 11.4.1.2.3 6 11) Clause 11.4.1.2.4 7 12) Clause 11.4.4.6 . 7 13) Clause 12.3.3.3.2.1 . 7 14) Clause 12.3.3.3.5.1 . 7 15) Clause 12.3.3.3
20、.7.3 . 8 16) Clause 12.3.4.2.2 8 17) Clause 12.3.4.2.7 8 18) Clause 12.3.4.2.8 9 19) Clause 12.3.7 9 20) Clause 13.2.1.1.5 11 21) Clause 13.2.2.1.1.2 . 12 22) Clause 13.3.1.1.1.1 . 13 Rec. ITU-T G.9701 (2014)/Cor.4 (12/2017) 1 Recommendation ITU-T G.9701 Fast Access to Subscriber Terminals (G.fast)
21、Physical layer specification Corrigendum 4 1) Clause 3.2.34 Revise the text of clause 3.2.34 “subcarrier group“ as follows: 3.2.34 subcarrier group: A group of G (where G = 1, 2, 4 or 84) adjacent subcarriers. NOTE Subcarrier groups are used to reduce the number of test parameter data points that ne
22、ed to be stored by and communicated between the FTU-O and FTU-R. Each subcarrier in a subcarrier group is characterized by the same value of a test parameter (see clause 11.4.1). 2) Clause 10.2.2.2 Revise the text of clause 10.2.2.2 “Initialization symbol encoder“ as follows: 10.2.2.2 Initialization
23、 symbol encoder SOC symbols are transmitted on the first s symbol positions of each logical frame (sds symbols for the downstream and sus symbols for the upstream); the value of sds is determined during the ITU-T G.994.1 handshake and the value of sus is communicated to the FTU-R in the O-SIGNATURE
24、message (see clause 12.3.3). However, if one of these s symbol positions is a sync symbol position, a sync symbol shall be transmitted in this position (not an SOC symbol), as described above. Bits of initialization data shall be modulated on the subcarriers of initialization symbols using 2-bit con
25、stellation mapping defined in clause 10.2.1.4. Cyclic extension and windowing of all initialization symbols shall be the same as applied for symbols of active lines during showtime. Constellation points on all subcarriers shall be rotated based on 2-bit numbers provided by the quadrant scrambler des
26、cribed in clause 10.2.2.4. The scrambler shall be used in the reset mode or in free running mode, depending on the stage of initialization (see clauses 12.3.3-12.3.5). In the reset mode, the scrambler shall be initialized at the beginning of each symbol with an 11-bit initialization seed. The seed f
27、or each line is determined by the VCE and communicated to the FTU-R during the ITU-T G.994.1 handshake. The VCE shall define the same seed for sync symbols and all initialization symbols transmitted over a particular line. In free-running mode, the scrambler shall be initialized with the selected se
28、ed at the beginning of the corresponding stage of the initialization. The downstream SOC symbols may be repeated (see clause 10.2.2.2.3) and may be modulated afterwards by an identification sequence (IDS) (see clause 10.2.2.2.2). 3) Clause 10.3.2.3.1 Revise the text of clause 10.3.2.3.1 “Control par
29、ameters for vectoring feedback reporting“ as follows: 10.3.2.3.1 Control parameters for vectoring feedback reporting The VCE communicates to the FTU-O a set of control parameters for vectoring feedback reporting defined in Table 10-9. 2 Rec. ITU-T G.9701 (2014)/Cor.4 (12/2017) Table 10-9 Control par
30、ameters for vectoring feedback reporting Parameter name Definition Vectored bands The downstream frequency bands for which the FTU-R shall send VF samples for the subcarriers through the vectoring feedback channel. The vectored bands shall be defined by indices of the lowest frequency and the highes
31、t frequency subcarriers. N_band denotes the number of vectored bands configured. No more than eight bands shall be configured (i.e., N_band 8). The configured bands shall be identified by their numbers: vb = 0, 1, 2, 3, 4, 5, 6, 7 assigned in the ascending order of subcarrier indices associated with
32、 the band. N_carrier(vb) denotes the number of subcarriers in frequency band number vb, and can be computed as the index of the stop subcarrier minus the index of the start subcarrier plus one. The vectored bands shall not overlap one another. F_sub The sub-sampling factor to be applied to the vecto
33、red bands. For every vectored band, the VF sample of the subcarrier with the smallest starting index shall be transmitted first, followed by the VF sample of every F_subth subcarrier within the vectored band. Selection of the starting index is specified in clause 10.3.2.5.1 for frequency identificat
34、ion and in clause 10.3.2.5.2 for time identification. Configured by the VCE and applied for each vectored band separately. F_block The block size (number of subcarriers) for grouping of VF samples. Configured by the VCE. The same block size configuration shall be used for all vectored bands (see Tab
35、les 10-10 and 11-41). B_min Lower bound of the bit index for reporting of a VF sample component (see clause 10.3.2.3.2). Configured by the VCE for each vectored band separately. B_max Upper bound of the bit index for reporting of a VF sample component (see clause 10.3.2.1). Configured by the VCE for
36、 each vectored band separately. L_w Maximum number of bits for reporting of a VF sample component. Configured by the VCE for each vectored band separately. If L_w is set to zero for a particular vectored band, that band shall not be reported. L_w shall be set to a non-zero value for at least one vec
37、tored band. Padding Indicates whether or not the FTU-R shall pad VF samples through sign extension or zero padding (Note) to maintain using L_w bits for reporting of a VF sample component if S 1: 0, 2, , 126, 127, 128 If q 1: 0 All valid values. 5) Clause 11.2.2.10 Revise the text of clause 11.2.2.1
38、0 “Inventory commands and responses“ as follows: 11.2.2.10 Inventory commands and responses The initialization flags request and the initialization flags reset request eoc commands shall only be supported from the FTU-O to the FTU-R. The initialization flags response and the initialization flags res
39、et response shall only be sent from the FTU-R to the FTU-O and shall contain the current value of the initialization flags. The following initialization flags are defined: The “previous-loss-of-power“ (PLPR) flag: This flag shall be set to 1 after a power-up of the FTU-R due to an interruption in th
40、e FTU-R electrical supply (mains) power. The flag shall be set to 0 after sending the initialization flags reset response. The “previous host reinit“ (PHRI) flag: This flag shall be set to 1 after an power-upexit from showtime of the FTU-R triggered by the NT host (e.g., FTU-R software reboot or L3
41、request by FTU-R). The flag shall be set to 0 after sending the initialization flags reset response. Rec. ITU-T G.9701 (2014)/Cor.4 (12/2017) 5 The value of the initialization flags shall be formatted as one byte 0000 00ba where “a“ is the value of the PLPR flag and “b“ is the value of the PHRI flag
42、. NOTE The FTU-O may first use the initialization flags request eoc command to read the PLPR and PHRI flags, and then, once the FTU-O manages to correctly read these flags, use the initialization flags reset request eoc command (see Table 11-29) to reset the values of these flags. 6) Clause 11.3.1.1
43、 Revise the text of clause 11.3.1.1 “Near-end anomalies“ as follows: 11.3.1.1 Near-end anomalies Loss-of-power interruption (lpr_intrpt): Excluding reinitializations triggered by the ME-O (see clause 12.1.2), this anomaly occurs upon entry into showtime when the time between the exit from the showti
44、me of the FTU-O and the first successful reception of an ITU-T G.994.1 message is less than 120 seconds and at least one of the following conditions is met: a far-end loss-of-power (flpr) primitive (see clause 11.3.3.2) is was declared before the exit from showtime, or the PLPR flag (retrieved from
45、the FTU-R) is set to ONE at the entry into showtime (see clause 11.2.2.10). This anomaly is only defined at the FTU-O. Host-Reinit interruption (hri_intrpt): Excluding reinitializations triggered by the ME-O (see clause 12.1.2), this anomaly occurs upon entry into showtime ifwhen the PHRI flag (retr
46、ieved from the FTU-R) is set to ONEat the entry into showtime (see clause 11.2.2.10). This anomaly is only defined at the FTU-O. Spontaneous interruption (spont_intrpt): Excluding reinitializations triggered by the ME-O (see clause 12.1.2), this anomaly occurs upon entry into showtime, after a succe
47、ssful fast initialization, after a successful full initialization, if the following three conditions are met: between the exit from showtime and the first successful reception of an ITU-T G.994.1 message a failed fast initialization occurred, and when the time between the exit from showtime of the F
48、TU-O and the first successful reception of a ITU-T G.994.1 message is less than 120 seconds, and neither an lpr_intrpt nor an hri_intrpt occurs at the entry into showtime. This anomaly is only defined at the FTU-O. 7) Clause 11.3.1.3 Revise the text of clause 11.3.1.3 “Near-end defects“ as follows:
49、11.3.1.3 Near-end defects Loss of signal (los): A reference power shall be established by averaging the ITU-T G.9701 receive power over the RMC symbol over a 0.1 s period interval and over a subset of subcarriers used for showtime, and a threshold shall be set 6 dB below this level. An los shall occur when the level of the ITU-T G.9701 receive power averaged over a 50 ms period interval (where these 50 ms intervals are contiguous) and over the same subset o
