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parrelium
join:2005-07-31

parrelium to TierX

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Re: High Speed 50/Optik 50 FAQs

Even so, with the attainables around 120/50, doesnt that mean the lines are capable of ~100 down and 40 up? Another tier to compete with shaw..
BadMagpie
join:2011-02-05

BadMagpie

Member

I read somewhere on here that the highest attainable sync rate with PhyR turned on (with the V1000h's current firmware) is actually 76/12. Without PhyR, errors increase and ping times get ruined (i.e. going from 5 to 15+ ms).
I'm left wondering though if you can still have PhyR on with a more upload-weighted sync rate, like 40/25.
TierX
join:2009-01-20
Canada

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to parrelium
said by parrelium:

Even so, with the attainables around 120/50, doesnt that mean the lines are capable of ~100 down and 40 up? Another tier to compete with shaw..

No unfortunately; 76/12 is the most we can with physical layer retransmission via PhyR. G.inp will let us squeeze out another 10mbps or so, but that'll have to wait.
TierX

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said by BadMagpie:

I read somewhere on here that the highest attainable sync rate with PhyR turned on (with the V1000h's current firmware) is actually 76/12. Without PhyR, errors increase and ping times get ruined (i.e. going from 5 to 15+ ms).
I'm left wondering though if you can still have PhyR on with a more upload-weighted sync rate, like 40/25.

In theory yes, that 90mbps aggregate with PhyR could be weighted any way we like. However in practice this would be very difficult, as offering much higher upstream rates gets risky due to upstream power back off.

Essentially, if we uncapped upstream rates, the subscribers on shorter loops who could get 30-40mbps upstream would completely knock out the U1 upstream band for subscribers on medium or longer loops; reducing those subscribers to only 1mbps upstream (just using the U0 upstream band, like with ADSL2+).

This is unfortunately due to the effects of far-end crosstalk, and while there is a way to fix this, you'll have to wait =).
BadMagpie
join:2011-02-05

BadMagpie

Member

Make sense. Though from this document:

»www.google.ca/url?sa=t&r ··· &cad=rja

it looks like the 30a bandplan has an upstream channel going from 22 MHz all the way to 30 MHz. How much far-end crosstalk would there be if this entire band were used, with little of the other upstream bands, given that its frequencies are beyond anything 17a uses? (Feel free to feed me technical documents and explanations, I have a background in engineering)
TierX
join:2009-01-20
Canada

TierX

Member

said by BadMagpie:

It looks like the 30a bandplan has an upstream channel going from 22 MHz all the way to 30 MHz. How much far-end crosstalk would there be if this entire band were used, with little of the other upstream bands, given that its frequencies are beyond anything 17a uses? (Feel free to feed me technical documents and explanations, I have a background in engineering)

30A wouldn't help at all, it has the same problems as 17A (which has an additional upstream band that 8B doesn't). 30A's U3 band goes from 23-30mhz, which sounds great, but because the frequencies are so high they get no bitloading past about 150m (30A is only 100mbps symmetric at up to around 130m). At which point the upstream performance deteriorates to 'slightly better' than 17A.

30A uses a wider tone spacing (8.625khz) and twice the symbol rate (8 ksymbol/second), this coupled with the wider bandwidth causes the line card density to be reduced by 50% (additional FFT/iFFT logic is required on the line card DSP's). Thus reducing a 192 port DSLAM to 96 port. On the CPE side, the BCM6368 chipset supports 30A, but it requires an additional AFE and a different line driver to support single-line 30A mode. Hopefully, it's clear why 30A is almost never deployed in practice =).

If you want to learn how to remove far-end crosstalk, read some of John Cioffi's papers on vectoring:

»www.stanford.edu/group/c ··· pub.html

The ITU-T has standardized on G993.5 as a method to use linear precoding to remove far-end crosstalk on VDSL2.
BadMagpie
join:2011-02-05

BadMagpie

Member

Real-time QR decompositions to remove crosstalk? That isn't going to help the DSLAM's power requirements is it?

How can vectoring be managed if there are one or more lines on the same cable are being offered by another ISP?
TierX
join:2009-01-20
Canada

TierX

Member

Thanks to process fabrication improvements, the additional power requirement from crosstalk cancellation isn't that bad.

The DSLAM's themselves will manage the vectoring automatically, the only requirement is wholesale ISP's will need to have G.vector compliant VDSL2 modems. In a situation where the ISP has their own DSLAM sharing a binder with another ISP's DSLAM, then vectoring won't be possible. Thankfully that doesn't happen on TELUS's FTTN network, as wholesale ISP's have always had access to our FTTN DSLAM's.

NorthVan
@telus.net

NorthVan

Anon

Called in yesterday and was upgraded to the 50mb service today, over the air (technician not required). Don't know how our complex is wired but the townhouse is brand new. Router is the ActionTec V1000H. Here are my speedtest results, over wireless:



Promotional price is $35 for the first six months, then $70/month. I also asked where I could view my usage online, and the rep told me that Telus doesn't enforce caps so not to worry. I've since discovered that the usage is printed on your monthly bill.