UPDATE Can BT’s Long Reach VDSL Fibre Broadband Help Rural Homes

Earlier this week BT announced plans to make a minimum broadband speed of 5-10Mbps universally available by around 2020 (here) and one part of that involved the use of Long Reach VDSL2 (FTTC), which could help bring “higher speed broadband to hard-to-reach communities“.

At the time of writing we still don’t know a great deal about the specific technology that Openreach have been playing with, although Thinkbroadband has today posted an interesting performance chart that depicts, albeit very hypothetically, what kind of difference it could make. Take with a pinch of salt.

Just to clarify. In the current ‘up to’ 40-80Mbps capable Fibre-to-the-Cabinet (FTTC) setup BTOpenreach runs a fibre optic cable from their telephone exchange to your local cabinet and then they use VDSL2 technology over the remaining copper wire that runs from the cabinet and into your home.

The length of that final copper run is crucial because signal attenuation and other environment factors or electrical interference will cause the performance to drop away sharply over distance (i.e. the shorter the copper cable, the better).

Generally speaking you need to live less than 300-400 metres (copper line length) from your street cabinet to get the best performance, while some people who reside just over 2000 metres (2km) away have reported speeds of 15Mbps and it dies away quickly after that (experiences will vary and it’s very difficult to know the true length of your line).

By comparison the new chart appears to suggest that at around 1.3km the current VDSL solution would deliver 30Mbps, yet with “long reach” you could get this same speed at around 1.6km to 1.8km from the cabinet. Similarly speeds of 10Mbps are achieved with VDSL at 1.8-1.9km, but “long reach” can apparently deliver the same at anything from 2.5km to 3.5km (this would put a lot of extra premises within reach).

Sadly not much accompanying content has been supplied for this illustration and our experiences of real-world FTTC / VDSL2 performance suggest that the predictions above are almost aggressively optimistic, although it’s not clear whether the Megabits per second (Mbps) rate is purely download speed or an aggregate of downloads and uploads combined.

In practical terms BT’s 5-10Mbps announcement doesn’t add much information to this, although they did specifically confirm that their plan would offer to “boost speeds for 400,000 customers currently getting under 3Mbps on their copper broadband.” This suggests a more targeted upgrade, rather than a general network-wide roll-out, but the details are still wafer thin.

In the past various upgrades have been suggested that could deliver a “longer reach” FTTC solution, such as VDSL Amplifiers or the similar SuperVector technology (here). But as Openreach told us earlier this year, they’re “just a nice idea and some simulations,” although we have asked for more details. It’s not even clear if Long Reach has been fully trialled yet, we’ve certainly seen no mention of it on their roadmap.

In the meantime BT has indicated that their future approach will depend upon the outcome of Ofcom’s Strategic Review and regulatory model, which by the end of this year may or may not cause a huge change in their plans and the market as a whole.

UPDATE 3:49pm

The illustration used above stems from Clive Selley’s (BT) speech on Tuesday and we’ve just been furnished with the relevant extract, which adds a bit more information.

Clive Selley said:

“My labs are also looking at new engineering solutions and we have some exciting new ideas to significantly raise broadband speeds on very long copper lines. We are going back to basics, revisiting the physics associated with high speed transmission over copper cables.

For example, at our labs up at Martlesham, Joe Garner and I recently reviewed a new technology that we are calling ‘Long-reach VDSL’. This demonstrated how we could take a 2km long copper line currently achieving 9Mb/s on standard VDSL, and increase this to 24Mb/s, and longer term, through standards changes, we could achieve even higher speeds.

The graph illustrates a recent lab measurement and some of the simulations we are carrying out. This is very exciting new technology and something that could play a key role in delivering Gavin’s [BT CEO] pledge.

Such new technology options are not without challenges: they may require new standards, they may require new products and they may require discussions with industry and the regulator alike regarding coexistence with legacy products. But the lab work proves that we can deliver technology enablers to materially uplift speeds for many customers on very long lines.”