Unprecedented Internet Bandwidth Reached at UCL

A group of scientists spearheaded by Lidia Galdino, Ph. D. in electronic and electrical engineering working currently as a researcher and lecturer at UCL, partnered with KDDI Research and Xtera for testing advanced data transfer technology. The team’s joint expertise warranted a spectacular speed of 178 Tbit/s, that is 178 million Mbit/s. Applied to Internet connexion, that would mean you are now theoretically able to get yourself Netflix library in its entirety in under 1 second. But let’s not get ahead of ourselves: no system in the today’s global IT infrastructure can provide even a half of this capacity yet, so the implementation of the innovation is still to come.

What is interesting to understand is how did the team achieve this record. The IT experts transferred the data over a fiberglass cable, which is of little wonder today — but they used a wavelength range (a spectrum of light) considerably larger than the usual one. If we convert that into frequency terms, the UCL team was able to secure a 16.8 THz bandwidth, while only 4.5 THz systems are being widely used today, and 9 THz ones just appearing in the market.

The signal power had to be amplified over such an expanded bandwidth, which required Lidia and her teammates to join several technologies available. The researchers handled the properties of specific wavelengths by using the newly developed technique Galdino et al. called ‘Geometric Shaping (GS) constellations’. The delusively esoteric name means that individual signals are combined using patterns that follow various properties of the light: its brightness, phase and polarisation.

This pioneering approach was honoured by an article appeared in IEEE Photonics Technology Letters journal, and this is unsurprising knowing that the innovation can be used on available infrastructure in a saving manner by only upgrading amplifiers along fibre lines. These are generally spaced 40…100 kilometres apart, and one upgrade would come to £16,000 expense, while running new fibre lines in cities and towns may cost as high as £450,000 a km.

As we have said above, the UCL laboratory witnessed an all-time high Internet speed that beat the previous record achieved by Japanese researchers by 20 percent and got really close to the limit of data transfer rate theorized by Claude Shannon, a mathematician from the U.S., back in 1949.

To give the reader an idea of how high this speed is, let’s take the example of the first-ever image of a black hole: the image obtained in 2019 was so big that it required half a tonne of hard disks for storage, and a plane was hired only to deliver it elsewhere. But today, with the record bandwidth, the said image could be sent over the Internet in under an hour!

Lidia Galdino, who is also a Royal Academy of Engineering Research Fellow, highlighted the fact that compared to 178 Tbit/s manageable with upgrades of the infrastructure already in use, the fastest of the existing cloud datacentre routes can only reach speeds as high as 35 Tbit/s.

The outbreak of COVID-19 pandemic brought a kick in demand for broadband connectivity: operators witness up to 60 percent rise in web traffic over the past six months. This translates into unmatched demand for ever-robust and capable broadband routes. But even without considering the current crisis, says Galdino, web traffic went exponential during the last decade, so traffic cost per bit of data is going down constantly. In this context, innovations such as the described technology are vital for preserving the trend and keeping up with tomorrow’s demands “that will continue to increase, with as yet unthought-of applications that will transform people’s lives,” concludes Galdino.

Funding for the work of Galdino’s team has been secured by the British Royal Society Research grant, the Royal Academy of Engineering, and the TRANSNET grant by the Engineering and Physical Sciences Research Council programme (EP/R035342/1).