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[gt94sss2]

Openreach are planning to run a new technical trial of Long Reach VDSL (LR-VDSL) across a number of exchange areas. This trial will run from August 2016.

BT have published STIN 522 (http://www.btplc.com/sinet/sins/pdf/STIN522v1p0.pdf) which gives the usual technical details.

ISP Review also cover this at http://www.ispreview.co.uk/index.php/2016/08/bt-reveal-tech-details-expanded-long-reach-vdsl-broadband-trial.html

[j0hn]

just had a we quick read, few interesting bits and pieces. vectoring must be used. g.inp on both up and downstream.no dlm in effect, entirely manual during trial.
an interesting part is...

In order to prevent  exchange  based ADSL  or ADSL2plus customers served via a  cabinet selected for  LR-VDSL  being  adversely  affected, these lines must be migrated to  an FTTC GEA  service  (either VDSL  or  LR-VDSL, depending on D-side  insertion loss measured  at 300kHz).   This means that  LR-VDSL  can be  safely deployed without  adversely  impacting  exchange  based services.   

does that mean anyone on a trial cab who has an adsl service must switch to vdsl?

[Weaver]

I wonder if this could some day help me? I'm around 5 miles from the exchange (66 dB downstream attenuation). Reading speeds off the graphs doesn't give great encouragement. However G.INP and SRA would be great, good additions even to a basic underlying service that is hardly any faster at my kind of length.

[renluop]

...does that mean anyone on a trial cab who has an adsl service must switch to vdsl?

Does the EU have to pay; why should he if satisfied currently?

[Chrysalis]

I take it as meaning they are going to switch all adsl customers to FTTC and then enable the low tones for the VDSL service.

[Weaver]

And if they get rid of ADSL entirely and switch to VDSL, what happens to customers who are five miles away? Is it the case that no-one is worse off on VDSL2 (maybe appropriately retuned if necessary) than in ADSL2+?

[Chrysalis]

in my view yes once those low tones are enabled, vdsl can cover the same distance.

[renluop]

Embarrassed to ask, but what is the insertion loss (12 to 40 db) the paper mentions; something like attenuation? What sort of distance from the cabs would that be?

[WWWombat]

Yes, insertion loss is the same as attenuation.

When measured at 300kHz, it is around 11dB per km on 0.5mm copper, or 14.6dB per km on 0.4mm copper.

I guess BT are aiming at this being used for lines between 1.1km and 3.6km where standard 0.5mm copper is in use.

[WWWombat]

The STIN itself thinks the shortest line is 1.25km, so perhaps their own spec of 0.5mm copper has an insertion loss of 10dB per km.

[WWWombat]

Ooh. An interesting snippet...

Profiles are used by the Element Management System (EMS) to configure various parameters on each DSLAM port (e.g. speed, noise margin, transmission mode etc.).  Although there are in excess of 10,000 profiles available for GEA-FTTC, the LR-VDSL trial will only use a  single profile. 

I wonder if all 10,000 profiles are used by DLM?

[Black Sheep]

The STIN itself thinks the shortest line is 1.25km, so perhaps their own spec of 0.5mm copper has an insertion loss of 10dB per km.

  Yup. 

[renluop]

Yes, insertion loss is the same as attenuation.

When measured at 300kHz, it is around 11dB per km on 0.5mm copper, or 14.6dB per km on 0.4mm copper.

I guess BT are aiming at this being used for lines between 1.1km and 3.6km where standard 0.5mm copper is in use.

As from the cabinet I guess?

[WWWombat]

As from the cabinet I guess?

Yes. The document specifies the insertion loss of the D-side.

Strictly, I think BT counts the D-side as the cabinet to DP, and measures the loss of this section in their cable records. I think the dropwire is considered separately, but perhaps BS can confirm what is likely to apply...

[S.Stephenson]

Seeing as ECI doesn't support upstream G.INP I don't suppose this will be any use in ECI.

They should get some sort of Behemoth cabinet that does ADSL/VDSL and G.Fast all in a single PCP or if you run G.Fast at 0-106 does it have the range of ADSL2+?