This is more of a random fun question I'm throwing out to everyone on the forum. Wondering if one of the VM Tech guys or one of the well informed forum members may be able to answer/speculate.
My question is.........How high can Virgin download/upload speeds go in the years ahead?
BT started with fixed rate ADSL of 0.5/1/2 Mb. Then ADSL max which capped at 8Mb then ADSL2 which capped at up to 20Mb. Now FTTC which started at up to 40down/10up and now 80down/20up and in some areas they are trialling 120Mb down on FTTC. Now they're rolling out FTTP on demand with speeds of up to 330Mb down.
Same with Virgin. I started with 0.5Mb in 2001 then moved up over the years from 1/2/10/50/60/100/120 and now 160Mb!
Anyone have any ideas what the max possible speeds we will see in the next 5-10 years without Virgin having to dig up the last leg (coaxial) part of the network and relying on exchange/node upgrades alone?
Also, can anyone explain why Virgin upload speeds still lag begind BT infinity? I'm currently getting 160Mb down and 12-13Mb up compared to 20Mb on BT infinity. I'm not complaining in the slightest! I'm just curious.
Not sure if I was dreaming or not, but I am sure I read somewhere just before Christmas, that VM were trialling 400Mbs in the I think Canterbury area. Maybe one of the enlightened members here will have the details.
We're on the EuroDocsis system, whereas the USA use Docsis, so data rates (and other important technicalities) are slightly different.
This gives you a good idea of the maximum data rates on the current Docsis/EuroDocsis system, just multiply by the number of channels you expect to have.
The figure in () is the one to look at as it's the useable ethernet speed after overheads have been taken out, but that's still shared by all users on that cable/node, so you personally don't get all that speed. You get a share of it.
e.g. On the current EuroDocsis 3.0 system if your hub modem has 8 downstream channels locked, then 400Mbps in total is bonded together over 8 x 256 QAM channels @ a symbol rate of 6.952 MSyms/s, which is shared between a few hundred users allowing a few of those users to max out to 120-161Mb for a short period of time.
How to work out data rates for channels:
Raw data rate (before overheads) = bits per symbol x number of symbols. Simple.
16 QAM = 4 bits per symbol of data
64 QAM = 6 bits per symbol of data.
256 QAM = 8 bits per symbol of data.
1024 QAM = 10 bits per symbol of data.
If you have two 16 QAM upstreams @ 5.12MSym/s that means:
4 bits x 5.12 = 20.48 Mbps raw data (17 Mbps after overheads) per 16 QAM upstream channel.
Or 6 bits x 5.12 = 30.72 Mbps (27 Mbps) per 64 QAM upstream channel.
So the upstream rates in the table above are based on 4 x 64 QAM channels, which none of us have yet. Some people have 2 x 64 QAM upstreams and other like me still have 2 x 16 QAM upstreams.
Why is it important to understand this? Because of the next bit...
So the figures above are obviously based on the Docsis rather than EuroDocsis system.
The current Docsis 3.0 modems we have (SH1, SH2) support a maximum of 400Mb down, 120Mb up as you can see. So we'd need new Docsis 3.0 modems with 24-32 channels or Docsis 3.1 modems (available 2015-2016).
A single 1024 QAM downstream would yeild around 69.52 Mbps (62 Mbps). So 24 channels x 62 = 1.5 Gbps.
1 Gbps requires a minimum of 16-18 downstream channels (maxed out with just one user on those channels not sharing), but more likely 24 downstream channels to distribute the load. So a Puma 6 or BCM 7145 chipset based modem.
As with the 400Mbps example, VM might be able to give users less than 30-40% (120Mbps-160Mbps on the current system) as throughput for a short period of time once it's shared between a large pool of users. Based on 1 Gbps total that would be 300-400Mbps per user.
Infrastructure upgrades to the CMTS's and throughout the network to "free up" and support these channels would be necessary as well as the capacity upgrades and noise busting to enable these higher modulation schemes to work.
So more likely to get lower data rates than these initially and less channels. Remember, these are just the maximums.
Because of the extensive work necessary for these upgrades, the fact the hardware isn't available yet for Docsis 3.1 and that VM is still rolling out the last two sets of upgrade programmes phase 1 will be a few years away at least, if it comes in that form.
What we might see in-between are higher down stream and upstream rates either based on the current or with a new modem that can support more Docsis 3 channels.
For example, as an intermediate step, Com Hem in Sweden are currently offering a 500/50 Mbps service with a Docsis 3 hub that supports 16 downstream channels and 4 upstream channels.
They state their service as 300-500 Mbps down and 30-50 Mbps up.
Can't be bothered to look up their symbol rate and frequency allocation but assuming it's similar to ours based on their modem:
16 DS @ 256 QAM = 16 x 50 Mbps = 800 Mbps.
4 US @ 64 QAM = 4 x 27 Mbps = 108 Mbps.
4 US @ 16 QAM = 4 x 17 Mbps = 68 Mbps which wouldn't really be enough support many users without implementing harsh upstream traffic management like VM has. Since they give a speed guarantee that's unlikely.
So it's more likely something like:
2 x US @ 64 QAM + 2 x US @ 16 QAM at a minimum = 88 Mbps total upstream.
Which is similar to our ratio of 3 users maxing out an upstream port, but in this case @ 30 Mbps, with a burst up to 50 Mbps when available.
Note: Lots of speculation here about the upstream.
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