UPDATE BT Prep Trial of Long Reach VDSL Broadband to Hit 10Mbps USO

In a predictable development Openreach (BT) has confirmed that their “very exciting” Long Reach VDSL (FTTC) broadband technology, which could be used to help deliver the future 10Mbps Universal Service Obligation (USO), will soon be leaving the labs and becoming a targeted network-based trial.

At present BTOpenreach’s dominant ‘up to’ 40-80Mbps capable Fibre-to-the-Cabinet (FTTC) technology works by running a fibre optic cable from the telephone exchange to your local street cabinet and then they using VDSL2 technology over the remaining copper wire (this runs from the cabinet and into your home).

The length of that final copper line is crucial because signal attenuation and other environment factors, such as external electrical interference or water damage, will cause the performance to drop away sharply over distance (i.e. the shorter the copper cable, the faster your broadband).

Generally speaking you need to live less than 300-400 metres (copper line length) from your street cabinet to get the best VDSL performance on Openreach’s existing 17MHz spectrum profile, while some people who reside just over 2000 metres (2km) away have reported speeds of 10-15Mbps and it dies away quickly after that (experiences will vary).

Openreach first started talking about the potential for Long Reach VDSL (LR-VDSL) last year (example) and CEO Clive Selley later confirmed that their lab simulations “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.”

However we still know very little about the technology and until now it has remained little more than a lab test and some simulations, although Openreach now seem to be progressing it towards a practical trial and this week we’ve also learnt a little more about how the service will work.

An Openreach Spokesperson said:

“Long Reach VDSL operates at higher power levels and utilises additional frequencies in order to increase broadband speeds and the distance over which they can be delivered. As a result, Long Reach VDSL has the potential to increase broadband speeds significantly over long copper lines, typically found in remote parts of the UK.

Long-reach VDSL could potentially double the length of copper line over which 10Mbps broadband speeds are available; it could be key to delivering a 10Mbps universal service.

However, such new technology options are not without challenges. The innovations involved may well require discussion with industry and the regulator on coexistence with legacy products (given the need to manage potential interference issues).

Nevertheless, to be clear: the laboratory work proves that we can deliver technology to increase speeds significantly for many customers on very long copper lines.”

At present existing VDSL services are very low power and only use a small amount of spectrum, although there are higher profiles (30MHz) available but not all hardware in the network supports that and elsewhere you can also run into other challenges when trying to increase the power. The issue of cost may also become a factor.

One of the reasons for VDSL to have its own street cabinet and run at a low power is to avoid causing problems for other broadband technologies, such as ADSL that is delivered from the telephone exchange. We also wonder if VDSL Vectoring (reduces cross-talk interference) will end up playing a greater role in the Long Reach service (so far Vectoring has only been deployed in a very limited number of busy areas).

In either case we should learn more as soon as Openreach has established a firm plan and time-scale for the trial, which they’ll want to progress quite quickly because the Government now plan to introduce the USO by “the end of 2017 or 2018” (here). We expect Long Reach VDSL, if it is deployed, will be tightly focused on helping only the most remote areas to get a faster connection (i.e. just those bits in the final 5% of UK premises that need help to achieve the USO via fixed lines).

UPDATE 3rd May 2016

We got a tiny bit of new information to add on top of the above. Apparently Openreach’s small-scale Proof of Concept (PoC) trial, which is set to last for 3 months, will involve a maximum of 200 lines and should begin early this very month.

The PoC is open to ISPs with existing FTTC lines in the PoC area with qualifying target lines (likely to mean sub-24Mbps lines and those at a certain distance from their street cabinet) and Openreach are currently working with impacted providers. We are still trying to find out precisely where the trial will take place.