Openreach UK in World’s First Trial of New Air-Blown Ribbon Fibre Cable

Openreach (BT) has claimed that they could boost the roll-out of their new 1Gbps capable Fibre-to-the-Premises (FTTP) broadband ISP network by using a new type of air-blown ribbon fibre cable, which can be deployed “five times faster” than conventional cabling and is now under trial in Leeds UK.

At present the operator is currently deploying their “full fibre” network to cover 3 million UK premises by the end of 2020 (so far they’ve already done over 900,000 premises – adding 13,000+ every week) and possibly reaching 10 million by around 2025. Naturally anything that can speed this process up would be a bonus to their plans and that’s where the “world’s first” trial comes into play.

The new cable “bonds individual ultrafast fibres together in a web-like pattern that allows increased packing density in a cable” and this enables engineers to blow the cables long distances without having to joint. The ribbon format also allows engineers to join up (splice) together 12 fibres simultaneously (much faster), rather than having to do them individually, as is the case with traditional cables.

On top of that the design creates additional space in the cable, which means you can fit more than 432 fibres into small diameter cable sheaths (in Openreach’s network it only takes 1 fibre to serve 32 FTTP connections). These cables can be used to feed large areas from Openreach’s telephone exchanges, helping to connect more homes and businesses, and in less time.

The other benefit from this is that they can be “blown” into underground ducting (i.e. using compressed air instead of the slow process of manual pulling), which thanks to the larger capacity means they’re utilising existing duct space more efficiently.

Andy Whale, Openreach Chief Engineer, said:

“The advantages of this clever technology to Openreach are that we can splice less often and when we do have to splice we can do it more quickly. This means we will be able to build the big fibre cables or ‘spines’ supporting all our city builds in less time, with a less labour intensive and disruptive approach.

As we build bigger fibre networks to support the roll out of FTTP – especially in cities – we need to install higher fibre count spine cables to our exchanges. With these new air blown cables, it means we no longer need to pull in a few hundred metres at a time.

Getting new larger fibre count cables through busy city centres where access is difficult and where ducts are already often nearly full is a real headache for our operational teams. We expect this cable to take a lot of their pain away. All this means we will be able to build our big fibre spine networks to support Full Fibre ambitions more quickly and more efficiently.”

The Air-Blown Wrapping Tube Cable™ (AB-WTC) itself has been created by Fujikura Europe, while the cable blowing machine (Tornado) comes from CBS Products. Apparently the latter machine can blow (and install) up to 60 metres of fibre per minute.

Openreach said they plan to scale-up the trial with a further deployment in other parts of the United Kingdom, before running an invitation to tender later this year.

Fujikura’s Summary of the Benefits

* Improved packing density & flexibility – cable diameters are much more economical on duct space and higher fibre counts can be achieved. Previously we have only been able to blow cables containing up to 276 fibres. As we build bigger and bigger fibre networks to support the roll out of FTTP to the cities we need to install higher fibre count spine cables to our exchanges of 432 fibres and above, but these can only be pulled in a few hundred metres at a time.

* The new air blown 432 fibre version of this cable is small in diameter (9.3mm) which means we can get more fibre installed when there is restricted duct space.

* With the air blown cable we are confident we can blow 2km or further through a sub duct without needing to joint, meaning cabling is quicker. We expect to joint typically around a quarter as often and when we do have to joint we can joint five times faster

* Longer lengths of cable can be accommodated on reels. This leads to greater installation efficiency

* Cables have a drier structure, meaning it is easier for engineers to handle during the installation process

* The speed of installation – when Spider Web Ribbon™ (SWR™) is used, engineers can splice 12 fibres at once. Traditional cables required fibres to be spliced individually.

* This increase in installation speed leads to a reduction in disruption to the general public on Highways and footpaths

* Fujikura has worked closely with Openreach to develop a range of cables that provide the benefits of SWR/WTC as described above while also being designed to be optimised for air-blown installation.

* The new higher capacity ribbonised cables are blown into underground ducting using the CBS Tornado blowing machine.