Gigabit-over-copper VDSL successor G.fast signed off at last

Big buildings like blocks of flats are way above Ethernet distance unless you go with fibre or add repeaters. Also, phone cables are already in - nobody likes to re-cable a building if they don't have to, especially a residential one where each property is owned by a different person.

Physics

Probably there isn't much more reach possible at 100Mbps. So they experiment with shorter distances which inherently allows more speed.

Shannon-Nyquist.

The future is fibre. Even VDSL2 is becoming a Niche for existing apartment blocks, hotels, guest houses etc that don't have Cat5e or similar. At about 900m to 1200m (depending on cross talk, noise, cable condition etc) the ADSL2+ becomes better than VDSL2. Most VDSL gear will fall back to ADSL2+ on poorer / longer lines.

Another aspect also is RFI production as you increase power and bandwidth for higher speeds.

It's Worse Than That It's Physics Jim

Probably best to complain to the person who invented physics on that one. Bloody inverse square law :P

I'd encourage reading up on this to understand why developments have followed the course that they have.

However, my quips aside, while there's only so much that can be done about boosting signal over line length in ideal theoretical conditions, in reality much interesting work has been done on compensating for cross talk with a technology known as vectoring. That's probably the best you'll get for your request. In the mean time you could always lobby for increased signal power and spend your life dodging angry hoards of radio hams. Don't forget though, every time you pump twice the energy into the phone line you'll get a 3 dB increase in signal and you quickly hit a situation of diminishing returns.

As an alternative you could push for line bonding, but if BT have to go out and install an extra new line for everyone, the economics of it quickly go down the toilet, you might as well just get them to roll out fibre.

As others have pointed out, a large part of the market are things like shopping centres, hotels, apartment blocks etc etc. There, it's about potential to re-use existing cabling, cabling distance, subscriber density, contention and all that good stuff. Plus avoiding OAM costs.

So wiring up Ethernet would mean installing additional ducts, cabling, wiring closets. Costs may vary depending on property type and building regs. So depending on building size, closet may need an Ethernet switch trunked back to one or preferably more main switches. Then each subscriber would need their own VLAN and some way to be able to point that VLAN at their chosen provider.. Unless you're not intending to give them any choice. And then it becomes a question of who'll manage and support that lot, especially if they're trying to manage multiple properties.

Then the ability to slap on a G.fast modem and having it work much the same way as a regular xDSL subscriber starts to look attractive. It's also a way to improve on existing pseudo-FTTH deliveries where the 'F' is really copper and the ASA lets ISPs get away with it. Where properties are dense enough, G.fast can aggregate subscriber connections back to a street cab & fibre conversion can happen there.