Hi
true, I read a sales man's slide
g.fast one can argue is more future proof, but it does require shorter loop length's to shine.
I suppose the difference here is what the german telco has already commited to a proper FTTC rollout (aka vectoring), whilst BT did their's with only half commitment essentially deciding they dont like the tech enough to put further money into it and instead move onto what allows them to market higher speeds, even if it benefits less lines. Thats the nature of the market we have in the UK.
It's interesting to note that VDSL can match speeds of G.Fast, the new 35b version of VDSL certainly can. The bit-rates are mostly if not almost entirely decided by the frequency range used, so they don't tend to differ too much.
G.Fast was designed to be used close to the user premises, which is why it uses time division multiplexing (this works best when lines are a similar length and short), and time division multiplexing allows for easier power saving options (at the cost of latency) which was important if powering small G.Fast nodes by sending power back down the telephone line. G.Fast time division multiplexing also allows symmetrical download and upload speeds, like 100/100, but that is harder to achieve when you have 100 G.Fast connections all terminating back in the same cabinet as noise and crosstalk is at it's worst, a problem that was largely avoided using smaller nodes.
BT using G.Fast from the same VDSL locations so line lengths are not reduced means G.Fast is not the better technology to use, but VDSL 35b would be better.
Basically the money was spent looking at G.Fast with nodes closer to premises, they then decided they didn't want that investment so BT went for a cheaper option of using G.Fast from existing FTTC cabinets (or close by), so have ended up with the wrong technology for that. We now have the additional problem of co-existence of VDSL using frequency division and G.Fast using time division emanating from the same location at the cabinet.
It's a Frankenstein monster of a decision.
Regards
Phil