Fixed Speed Drop Since PlusNet Offer £2.99 Unlimited

[#1]

apollo1:
FTTC only suffers from crosstalk that can affect upstream performance, if you are having downstream issues this is not due to crosstalk, please use google and do some your own research too and you will find that the technology used for FTTC (VDSL) is not susceptible to crosstalk affecting downstream rates.

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Although I can understand your reasoning behind crosstalk, VDSL only suffers significant performance degradation from FEXT (Far-End CrossTalk) and this problem does not exist in the downstream direction and would not cause my downstream issues. (frequency division multiplexing with four frequency bands (two for upstream and two for downstream) in the138-kHz-to-12-MHz frequency range where FEXT noise is the major crosstalk impairment. It requires power-back off in the upstream direction.)

Also.. bump bump bump...
I've posted rather shocking speed test results can someone from PN get back to me?

[#2]

I'm not sure where you've got the idea that crosstalk only affects upstream from, but the G.993.5 vectoring ITU recommendation quite clearly refers to both downstream and upstream, including:

Quote from: Rec

5.2 Downstream vectoring For relatively short lines and high-bandwidth systems such as VDSL, self-FEXT is the limiting factor for downstream data rates. This Recommendation defines multi-line pre-coding at the AN to mitigate FEXT in the downstream direction ...

[#3]

bump again - can someone from PlusNet support get back to me regarding my speed. I resubmit my last two speed tests (7mb and 27mb):
#1
http://imgur.com/Hdn53lg
#2
http://imgur.com/Mp5ydIJ
ejs, some reading for you:
http://www.analog.com/library/analogdialogue/archives/34-05/vdsl/

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The far-end crosstalk (FEXT) noise is generated between signals travelling in the same direction in a cable. FEXT is the dominant crosstalk noise source in VDSL. Its power spectral density: PSDFEXT = kLƒ2 |Hch(ƒ)|2 Approx. Equal kLƒe-(2La(ƒ)) depends on the frequency, f, the length of the cable segment, L, that the two signals run in parallel, and the channel transfer function Hch(f). Because the channel transfer function is an exponential function of L, the power spectral density of the FEXT noise is small for large values of L and is relatively high for low L. In the upstream direction (Figure 4), transmitter Tx4US is much closer to ONU than Tx2US and Tx3US. Tx4US will inject a relatively high level of FEXT noise in pairs2 and 3. The upstream signals from these pairs are heavily attenuated at the point where the FEXT noise is injected. The result is that in the upstream direction the FEXT noise from sources close to the ONU (CO) will degrade significantly the SNR of the sources far away from ONU, collocated in the same binder. The solution consists in reducing the transmit power, depending on the distance from the transmitter location to the ONU(CO). This problem does not exist in the downstream direction (all the transmitters are located at ONU/CO).

[#4]

Yes I did read that earlier. I think the part you highlighted in bold is only referring to a particular aspect of crosstalk - that crosstalk from the upstream of a short line would significantly affect a longer line because the signal from the short line would be stronger, and upstream power back-off avoids that aspect. It doesn't mean crosstalk doesn't exist for downstream.

[#5]

@DaveA - I can't see a Ticket open on your account. If you've a fault with your service, we'd need you to raise a fault at http://faults.plus.net so our Faults Team can investigate this for you.