Telecommunications Industry Association
TR41.9.1-08-11-006
Document Cover Sheet
Project Number
PN-3-0016-RV2 (to become TIA-968-B)
Document Title
Proposed corrections to VDSL2 requirements in dpANS TIA-968-B.
Source
Verizon
Contact
Trone Bishop
13100 Columbia Pike
Silver Spring, MD 20904
Distribution
TR-41.9.1, at Nov. meeting in Costa Mesa CA
Intended
Purpose of
Document
(Select one)
X
Phone:
301-236-3754
Email:
trone.t.bishop.jr@verizon.com
For Incorporation Into TIA Publication
For Information
Other (describe) Notices
The document to which this cover statement is attached is submitted to a Formulating Group or subelement thereof of the Telecommunications Industry Association (TIA) in accordance with the provisions
of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of which
provisions are hereby incorporated by reference.
This document has been prepared by Verizon to assist TIA Engineering Committee TR-41. It is proposed
to the TR41.9 subcommittee as a basis for discussion and is not to be construed as a binding proposal on
Verizon. Verizon specifically reserves the right to amend or modify the material contained herein and
nothing herein shall be construed as conferring or offering licenses or rights with respect to any
intellectual property of Verizon other than provided in the statement above.
Abstract
At the August meeting of TR41.9.1, the proposed requirements for the 21,000 to 23,000 kHz and
23,000 to 30,000 kHz bands associated with profile 17a were eliminated without a contribution
explaining the rationale or justification being noted in the August 2008 TR41.9.1 meeting report.
In addition, the VDSL2 transverse balance frequency spectrums for profile 17a were revised
without a contribution explaining the rationale or justification being noted in the August 2008
TR41.9.1 meeting report. This contribution proposes correcting the VDSL2 longitudinal output
voltage limits and transverse balance limits to provide consistency with the recommendations of
NIPP-NAI and the methodology for determining xDSL harms prevention criteria in T1.417-2003.
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Telecommunications Industry Association
TR41.9.1-08-11-006
VDSL2 Longitudinal Output Voltage Limits
As described more fully in contribution TR41.9.1-08-08-008R1, the methodology for determining
longitudinal output voltage requirements for xDSL in T1.417-2003 takes into consideration the
services of other customers that may use higher frequencies on twisted pairs in the same cable.
For other xDSL technologies, the LOV limits are applicable to a bandwidth that is four times the
operating bandwidth of the xDSL equipment. Since there currently is no xDSL technology using
frequencies higher than VDSL2, the LOV limits for VDSL2 do not need to be greater than 30
MHz. This may change in the future, but currently LOV limits are not needed beyond 30 MHz. At
the present time, all VDSL2 terminal equipment is subject to LOV limits up to 30 MHz.
Amendment 1 of G.993.2 created several VDSL2 profiles having significantly different frequency
spectrums than VDSL or VDSL2. Further study indicates that some VDSL2 profiles are more
likely to be used in specific subscriber loop cables than other VDSL2 profiles due to the
significant deployment range limitations of some VDSL2 profiles. In view of this, contribution
TR41.9.1-08-08-008R1 proposed a significant reduction in the LOV test frequency range for
VDSL2 profiles that are not likely to be used in the same cables as VDSL2 equipment operating
at substantially higher frequency spectrums.
For example, the 8a, 8b, 8c, and 8d VDSL2 profiles might be used in the same loop cable as
VDSL2 equipment operating with the 12a or 12b profile but it is not likely that VDSL2 equipment
using the 8a, 8b, 8c, and 8d profiles will be used in the same loop cables as VDSL2 equipment
using the 17a or 30a profiles. For this reason, contribution TR41.9.1-08-08-008R1 proposed
limiting the LOV frequency range for profiles 8a, 8b, 8c, and 8d to 12,000 kHz maximum.
Likewise, since VDSL2 equipment with the 12a and 12b profiles might be used in the same cable
as VDSL2 equipment with the 17a profile, but is not likely to be used in the same loop cables as
VDSL2 equipment using the 30a profile, contribution TR41.9.1-08-08-008R1 proposed limiting the
LOV frequency spectrum for profiles 12a and 12b to 21,000 kHz maximum (which is frequency at
which that particular downstream band of profile 17a drops to -80 dBm/Hz.
The issue involves the VDSL2 17a profile. Contribution TR41.9.1-08-08-008R1 indicated that the
17a profile might be used in the same cable as VDSL2 equipment (from the same or a
competitive carrier) that is using the 30a profile. For that reason, contribution TR41.9.1-08-08008R1 proposed keeping the existing LOV requirements for profile 17a in the 21,000 kHz to
30,000 kHz range.
At the August meeting of TR41.9.1, the LOV requirements for profile 17a in the 21,000 to 23,000
Hz and 23,000 to 30,000 Hz bands were eliminated from dpANS TIA-968-B without a contribution
explaining the changes or justification being noted in the meeting report. This contribution
proposes restoring the LOV requirements for profile 17a in the 21,000 to 23,000 Hz and 23,000 to
30,000 Hz bands based on the rationale provided above and in contribution TR41.9.1-08-08008R1.
VDSL2 Transverse Balance Limits
The methodology for determining transverse balance requirements for xDSL in T1.417-2003
takes into consideration the operating frequency spectrum of the equipment. At the August
meeting of TR41.9.1, the VDSL2 transverse balance frequency spectrum for profile 17a was
revised without a contribution explaining the changes or justification being noted in the TR41.9.1
meeting report.
The VDSL2 technical criteria in dpANS TIA-968-B were provided by the NIPP-NAI subcommittee
based on Amendment 1 of ITU-T G.993.2 and the principles for determining spectrum
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Telecommunications Industry Association
TR41.9.1-08-11-006
compatibility in the Loop Spectrum Management standard T1.417-2003 (R2007).1 Any significant
changes to the VDSL2 technical criteria should have come from, or at least been coordinated
with, NIPP-NAI.
The methodology in section A.2.3 of T1.417-2003 for determining the frequency spectrum for
transverse balance testing includes all upstream and downstream frequencies where equipment
is allowed to generate power within 20 dB of the peak power in that part of the PSD mask.
The current frequency spectrum for transverse balance testing associated with VDSL2 profile 17a
is specified out to 18,000 kHz which does not take into consideration a portion of the profile 17a
PSD mask that is allowed to have significant power, i.e., the spectrum from 18,000 kHz to 21,000
kHz. For profile 17a, the peak PSD value of the third downstream band (-56.5 dBm/Hz) extends
out to 17,664 kHz and then the PSD mask gradually slopes down to a -80 dBm/Hz limit at 21,000
kHz. The upper frequency limit proposed by NIPP-NAI for transverse balance testing was 21000
kHz. The frequency at which the PSD mask is 20 dB lower than the peak PSD in that band is
calculated to be 20,466 kHz.2
To provide consistency with methodology for determining xDSL harms prevention criteria in
T1.417-2003, this contribution proposes changing the upper frequency for transverse balance
testing associated with VDSL2 profile 17a from 18,000 kHz to 20,466 kHz.
1 T1.417-2003 (2007), Spectrum Management for Loop Transmission Systems.
2 The breakpoint frequency is equal to 10 x, where x is equal to [ 20 (log10 fint - log10 foh) / PSDfint – PSD1 ]
+ log10 foh. For VDSL2 profile 17a, fint is 21000 kHz, foh is 17664 kHz, PSDint is -80 and PSD1 is -56.5. For
these values, the breakpoint frequency equals 20,466 kHz (when rounded to the nearest kHz).
a. -56.5 – (-80.0) = 23.5
b. If foh is 17,644,000 Hz, then log10 foh = 7.247089056
c. If fint is 21,000,000 Hz, then log10 fint = 7.322219294
d. log10 fint - log10 foh = 7.247089056 - 7.322219294 = 0.075130238.
e. 20 x 0.075130238 = 1.50260476.
f. 1.50260476 ÷ 23.5 = 0.063940628
g. 0.063940628 + 7.247089056 = 7.311029684
h. 10 7.311029684 = 20,465,845 (which rounded to the nearest kHz is 20466 kHz)
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Telecommunications Industry Association
TR41.9.1-08-11-006
Proposals
1. In Table 5.3.8-7, insert a -80 dBVrms maximum longitudinal output voltage requirement in the
21,000 to 23,000 Hz and 23,000 to 30,000 Hz bands for VDSL2 TE operating with profile 17a.
New text is underlined. The table notes remain the same.
Table 5.3.8-7 – Maximum longitudinal output voltage for VDSL2 TE
Frequency
Maximum longitudinal output voltage
Band
(dBVrms) in all 4 kHz bands averaged over
(kHz)
a minimum period of 1 second (see note 3)
(see notes 1 and 2)
Profiles 8a,
8b, 8c, and 8d
Profiles
Profile
Profile
12a and 12b
17a
30a
fa (note 1) to fb (note 2)
-50
-50
-50
-50
fb (note 2) to 3,750
-80
-80
-80
-80
3,750 to 5,200
-50
-50
-50
-50
5,200 to 8,500
-80
-80
-80
-80
8,500 to 12,000
-80
-50
-50
-50
-80
-80
-80
21,000 to 23,000
-80
-80
23,000 to 30,000
-80
-50
12,000 to 21,000
2. In Table 5.3.8-12, change the upper frequency of the transverse balance frequency range for
VDSL2 over POTS profile 17a and VDSL2 all digital mode profile 17a from 18,000 kHz to 20,466
kHz.
Table 5.3.8-12 – Frequency ranges of transverse balance requirements for SMC6, VDSL and VDSL2 equipment
Interface
Frequency range
(kHz)
Longitudinal
termination
(RL) (ohms)
Metallic
termination
(RM) (ohms)
SMC6
13.6 to 12,000
90
100
VDSL over POTS
13.6 to 12,000
90
100
VDSL2 over POTS profiles 8a, 8b, 8c, and 8d
13.6 to 8,500
90
100
VDSL2 over POTS profiles 12a and 12b
13.6 to 12,000
90
100
VDSL2 over POTS profiles 17a
13.6 to 20,466
90
100
VDSL2 over POTS profiles 30a
13.6 to 30,000
90
100
VDSL2 all digital mode profiles 8a, 8b, 8c, and 8d
0.2 to 8,500
90 or 500
100
VDSL2 all digital mode profiles 12a and 12b
0.2 to 12,000
90 or 500
100
VDSL2 all digital mode profiles 17a
0.2 to 20,466
90 or 500
100
VDSL2 all digital mode profiles 30a
0.2 to 30,000
90 or 500
100
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