General Discussion
  >> Local Loop Unbundling & Regulation Issues


Register (or login) on our website and you will not see this ad.


Pages in this thread: 1 | 2 | 3 | (show all)   Print Thread
Standard User nemeth782
(newbie) Mon 08-Mar-10 17:18:10
Print Post

Is LLU Exchange based VDSL2 allowed or not?


[link to this post]
 
I've wondered about this question for a while, as it seems many LLU providers already have VDSL2 support at their DSLAM/ISAM.... *cough*Be*cough*

I've previously been lead to believe that Ofcom did not allow VDSL to be deployed from the exchange but I don't actually remember seeing any evidence for this being based on anything.

Reading the ANFP: http://www.niccstandards.org.uk/files/current/nd1602... it would seem that it is POSSIBLE for VDSL2 to breach the ANFP depending on power settings etc (page 27, section B.2), but this would not preclude it assuming the power levels were manually set, surely?

The ANFP also says that it will be revised when VDSL2 is standardised, yet as far as I'm aware there is no newer version yet?

Ofcom also seem to have looked at exchange based VDSL ( http://www.ofcom.org.uk/static/archive/ra/topics/int... ), and while this basically says "it will suck and have poor upload due to interference", it at no point precludes it being used and it should still be better than ADSL2+.

With the deployment and widespread use of VDSL2 via FTTC just around the corner, it seems senseless to disallow it from the exchange at this point!
Standard User nemeth782
(newbie) Mon 08-Mar-10 17:21:57
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: nemeth782] [link to this post]
 
In fact, those of us with exchange based lines with no cab between us and the exchange, must have (if I am reading this correctly) an "E/O Exchange outlet" rather than an E-side line....

And the Ofcom document I linked seems to say that while the market opportunity may be small, VDSL would be viable for us?
Administrator MrSaffron
(staff) Mon 08-Mar-10 22:14:42
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: nemeth782] [link to this post]
 
Personally I'd push for FTTH if close enough to not warrant a cabinet

Andrew Ferguson, andrew@thinkbroadband.com
www.thinkbroadband.com - formerly known as ADSLguide.org.uk
The author of the above post is a thinkbroadband staff member. It may not constitute an official statement on behalf of thinkbroadband.


Register (or login) on our website and you will not see this ad.

Standard User nemeth782
(newbie) Tue 09-Mar-10 07:11:25
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: MrSaffron] [link to this post]
 
Right, but that still requires investment.

This could be switched on tomorrow - the ISAMs already support it, all the hardware is there, just new CPE - a VDSL Router - would be needed. Those with EO lines have no prospect of FTTC EVER, and so whichever provider did it would have a captive audience across 1000+ unbundled exchanges, for no additional network investment.

Logically the interference impact, NEXT and REIN, on neighboring lines of having VDSL injected halfway down the bundle at the cabinet is far more significant than having it put on at the exchange, as the other lines have attenuated by the time the cabinet is reached....

So if VDSL is now allowed at cabs, there is no reason to disallow it from the exchange.

Edited by nemeth782 (Tue 09-Mar-10 07:12:47)

Standard User boggits
(knowledge is power) Thu 11-Mar-10 17:04:47
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: nemeth782] [link to this post]
 
Except for the fact that VDSL2 noise inside the exchange *may* cause interference with ADSL2+ in the exchange frown if there was no ADSL2+ in the exchange then you could use VDSL2 from the exchange

Standard User nemeth782
(newbie) Thu 11-Mar-10 17:42:00
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: boggits] [link to this post]
 
True, this is possible

But surely VDSL2 from the cabinet would cause even more interference on ADSL2+ from the exchange, as the ADSL2+ signals will be attenuated by the cabinet while the VDSL2 signals will be strong?

Given that, and we are still allowing VDSL2 from the cabinet, why not allow it from the exchange?
Standard User chewystuey
(knowledge is power) Thu 11-Mar-10 22:33:14
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: nemeth782] [link to this post]
 
it's late, I am not thinking straight, but...

if you're a cabinet, whilst noise and interference may be strong so is the signal.

by the time you get back to the exchange the signal is severely weakened but noise from VDSL2 lines would still be strong.

lastly you state that people could turn up exchange based VDSL2 with no CAPEX, which is clearly wrong.

Whilst ISAMs do support VDSL2 it is, to my knowledge only some of the newer models that support a VDSL2 line card that is backwards compatible with ADSL.
Older ISAMs do, I believe, continue to run a separate line card for separate technologies.

Even if it were you'd have to reconsider your backhaul costs as you're opening the path for a doubling of access speeds.
Standard User nemeth782
(newbie) Fri 12-Mar-10 22:42:03
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: chewystuey] [link to this post]
 
ok...

E is exchange, C is cab, H is home. Numbers are signal strength, F is fibre.

ADSL2+
E 9 9 9 9 8 8 8 8 C 7 7 7 7 6 6 6 6 5 5 5 5 4 4 4 4 H
VDSL2
E 9 9 9 9 8 8 8 8 C 7 7 7 7 6 6 6 6 5 5 5 5 4 4 4 4 H

With exchange based VDSL, at least the ADSL is of the same strength.
Now FTTC:


ADSL2+
E 9 9 9 9 8 8 8 8 C 7 7 7 7 6 6 6 6 5 5 5 5 4 4 4 4 H
VDSL2 FTTC
E F F F F F F F F C 9 9 9 9 8 8 8 8 7 7 7 7 6 6 6 6 H

Here the ADSL2+ is suffering from having to "compete" with a stronger VDSL signal at the cabinet.

So surely crosstalk and interference is more of an issue with FTTC than exchange based VDSL2?
Standard User Ignitionnet
(fountain of knowledge) Sat 13-Mar-10 10:11:53
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: nemeth782] [link to this post]
 
And in the upstream direction, noting that the two don't follow the exact same split...?

Have a nose at http://www.broadbandreports.com/r0/download/1456040~...

Stuck on the One Way Internet?

Edited by Ignitionnet (Sat 13-Mar-10 10:24:23)

Standard User dslamdunk
(regular) Sun 21-Mar-10 10:09:48
Print Post

Re: Is LLU Exchange based VDSL2 allowed or not?


[re: chewystuey] [link to this post]
 
I agree the ANFP is ambiguous regarding VDSL in the exchange.

However Capex would be minimal for us - our DSLAM chassis already operational in the exchange takes multiple cards (EFM, ADSL2, VDSL)

You have to take into account the CAL in SLU/FTTC so as not to interfere with the lines in the PCP still connected back at the exchange so you don't get the full capabilities of VDSL anyway (although we are working on getting every house in the village on our VDSL service leaving none linked back to the exchange and then asking Ofcom for an exemption to ANFP for that PCP since there would be no lines to interfere with!!)

So far we have found that VDSL2 at the cabinet gives, as expected, superior speeds over ADSL2 for quite some distance from the cabinet.
We haven't tried ADSL2 in the cabinet (the above compares effect over copper distance from exchange for ADSL2 with from cab for VDSL).
The advantage, in SLU/FTTC could be beyond say 2km from the cab when VDSL and ADSL2 give similar speeds: you then have the possibility of line bonding on ADSL2 (which you can't do on VDSL) meaning those houses still far from the cabinet could be rewarded further - although they would have to pay for 2 lines.

We have done bonding in ADSL2 at the exchange and it works very well - doubling speeds. e.g. one premises is on 42Mbps sync (1.6Mbps upload).

We could try VDSL2 in the exchange as an experiment - I will ask OFCOM for further guidance - because this would avoid having to use 2 lines (ADSL2 bonding) for an EO customer, or a customer not on an FTTC PCP, wanting more than 20Mbps.

Whilst FTTH is not yet realistic on cost (and no demand for it yet) in our small deployment, these things are worth exploring using the copper.
Pages in this thread: 1 | 2 | 3 | (show all)   Print Thread

Jump to