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Author Topic: xDSL FDD Bands  (Read 232 times)

burakkucat

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xDSL FDD Bands
« on: May 23, 2019, 09:44:58 PM »

For ADSL/ADSL2/ADSL2+ (ITU-T G.992.1, G.992.3, G.992.5) circuits I always use the following definition for the FDD (frequency division duplex) bands --

DS > 32 > US > 6

Where DS & US are the "receive" & "transmit" (or "return from" & "go to") bands relative to the CPE and the numbers are the sub-carrier (or tone) index. (The observant will note that I ignore sub-carrier index 32 and leave it as a sort of no-man's-land between the two bands.)

For profile 17a VDSL2 (ITU-T G.993.2) circuits I have not been able to find a definitive statement of the sub-carriers for each FDD band. I have looked at many ITU-T recommendations without success. Could somebody point me in the right direction, please?

I have many data sets, for VDSL2 circuits, archived and decided to extract the "Discovery Phase (Initial) Band Plan" (rather than the "Medley Phase (Final) Band Plan") from each and look to see if there was commonality across all the data sets. A rather surprising result was obtained --

Discovery Phase (Initial) Band Plan

US: (0,95) (696,1183)
US: (0,95) (868,1207) (1972,2783)
US: (0,159) (876,1199) (1980,2775)
US: (6,31) (882,1193) (1984,2770)
US: (7,32) (871,1205) (1972,2696)
US: (7,32) (871,1205) (1972,2782)

DS: (32,687) (1192,1627)
DS: (32,859) (1216,1963) (2792,3939)
DS: (32,859) (1216,1963) (2792,3959)
DS: (33,857) (1218,1959) (2795,4083)
DS: (33,859) (1216,1961) (2793,3863)
DS: (33,859) (1216,1961) (2793,3959)
DS: (33,859) (1216,1961) (2793,3970)
DS: (40,863) (1212,1963)

Hmm . . . :hmm:
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Weaver

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Re: xDSL FDD Bands
« Reply #1 on: May 24, 2019, 12:32:14 AM »

I am reading, but the morphine is making the words wander in the window…
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burakkucat

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Re: xDSL FDD Bands
« Reply #2 on: May 24, 2019, 09:34:59 PM »

Thinking about this some more, I suspect I am asking if anyone would be able to point me towards the specification for Profile 17a VDSL2, please.  :-\
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ejs

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Re: xDSL FDD Bands
« Reply #3 on: May 26, 2019, 07:22:02 PM »

The European band plans are defined in Annex B of the ITU-T G.993.2 document. They are specified with the edge frequencies in kHz for the bands, not tone numbers. The variant of band plan 998ADE17 that has US0 compatible with ADSL Annex A upstream will be the one Openreach is using.
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burakkucat

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Re: xDSL FDD Bands
« Reply #4 on: May 26, 2019, 10:20:31 PM »

Thank you, that is most helpful. Once again, I am guilty of not seeing what is right in front of my nose.  :-[

Having looked at Table B.1 and then divided the given frequencies by 4.3125 kHz per sub-carrier (a.k.a. tone), I will use the following definition --

4096 >  DS3 >= 2783
2782 >= US2 >= 1972
1971 >= DS2 >= 1206
1205 >= US1 >=  870
 869 >= DS1 >    32
  32 >  US0 >=    6
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