University College London

UCL sets internet speed record of 178Tbps

20 August 2020 | Melanie Mingas

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University College London (UCL) has recorded the world’s fastest data transmission speed, reaching 178 terabits a second – or 178,000,000 megabits a second – by using a bandwidth of 16.8 THz.

At double the capacity of any system currently deployed in the world, the speed was close to the theoretical limit of data transmission set out by American mathematician Claude Shannon in 1949.

The record was achieved by a research team led by Dr Lidia Galdino (pictured), lecturer at UCL and Royal Academy of Engineering research fellow, in collaboration with Xtera and KDDI Research.

Not only did they achieve the speeds – outperforming the previous record set by researchers in Japan by one fifth – the team also found such speeds could be deployed on already existing infrastructure.

In “real terms”, 178 terabits a second is so fast it would be possible to download the entire Netflix library in less than a second. Or it would take less than an hour to download the data that made up the world’s first image of a black hole – an image so big that it had to be stored on half a ton of hard drives and transported by plane.

Dr Galdino said: “While current state-of-the-art cloud data-centre interconnections are capable of transporting up to 35 terabits a second, we are working with new technologies that utilise more efficiently the existing infrastructure, making better use of optical fibre bandwidth and enabling a world record transmission rate of 178 terabits a second.”

The record was achieved by transmitting data through a much wider range of colours of light, or wavelengths, than is typically used in optical fibre. While current infrastructure uses a limited spectrum bandwidth of 4.5 THz, with 9THz commercial bandwidth systems entering the market, for this project researchers used a bandwidth of 16.8 THz.

To do this, researchers combined different amplifier technologies needed to boost the signal power over this wider bandwidth and maximised speed by developing new Geometric Shaping (GS) constellations. These are patterns of signal combinations that make best use of the phase, brightness and polarisation properties of the light, manipulating the properties of each individual wavelength.

UCL said the benefit of the technique is that it can be deployed on already existing infrastructure cost-effectively, by upgrading the amplifiers that are located on optical fibre routes at 40km to 100km intervals. This would mean that upgrading an amplifier would cost £16,000, while installing new optical fibres can, in urban areas, cost up to £450,000 a kilometre.

Dr Galdino added: “Independent of the Covid-19 crisis, internet traffic has increased exponentially over the last 10 years and this whole growth in data demand is related to the cost per bit going down. The development of new technologies is crucial to maintaining this trend towards lower costs while meeting future data rate demands that will continue to increase, with as yet unthought-of applications that will transform people’s lives.”

This work was funded by the Royal Academy of Engineering, The Royal Society Research grant, and the EPSRC programme grant TRANSNET.