The operator is testing the new type of optical fibre cable at its R&D labs, suggesting they could reduce latency by up to 50%

Today, BT has announced that it is now trialing a new type of fibre optic cable that includes a hollow, air-filled core.  

The idea behind the hollow core is simple enough. Currently, optical fibre uses a transparent solid glass core, allowing light to pass through it and thus convey information. However, despite using the clearest glass possible, the material’s inherent, miniscule opacity will ultimately interfere with the light’s transmission, especially over long distances. 

Hollow core fibre can theoretically overcome this challenge by allowing light to travel directly through air within a glass casing. 

This concept has been being developed for a number of years, though various technical challenges remain. 

Now, BT is directly trialling the technology, installing a 10km hollow fibre cable at the company’s R&D facilities in Adastral Park, Ipswich. Working alongside Luminosity, a Southampton University spin out company, and Mavenir, the operator intends to explore various use cases, including those related to 5G networks and ultra-secure communications, like Quantum Key Distribution (QKD).

In their work with Mavenir, BT has already demonstrated that hollow core fibre can increase the distance between street antennas and the back-end processing in exchanges, with the low latency provided meaning that more 5G antennas could be served from one exchange or cabinet.

In total, BT suggests that the hollow core fibres could reduce latency by up to 50%.

“This new type of fibre cable could play an important role in the future of the world’s communications infrastructure, heralding a step-change in capability and speed, to keep up with the demands for high-speed, low latency communications driven by 5G networks, streaming, and more,” said Professor Andrew Lord, BT’s Head of Optical Network Research.

While existing fibre will suffice for conventional mobile and fixed broadband demand for many years to come, these hollow fibre trials will offer valuable insight into what could be the future of low latency, fixed connectivity.


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