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developed a new, simplified receiver to be used in optical access networks:
the links connecting internet subscribers to their service providers.
“To maximise the capacity of optical fibre links,
data is transmitted us-
ing different wavelengths, or colours, of light. Ideally, we’d dedicate a
wavelength to each subscriber to avoid the bandwidth sharing between the
users. Although this is already possible using highly sensitive hardware
known as coherent receivers, they are costly and only financially viable in
core networks that link countries and cities. Their cost and complexity has
so far prevented their introduction into the access
networks and limits the
support of multi Gb/s (1 Gb/s=1000 Mb/s) broadband rates available to sub-
scribers,” said co-author and Head of the Optical Networks Group, Profes-
sor Polina Bayvel (UCL Electronic & Electrical Engineering).
The new, simplified receiver retains many of the advantages of coherent
receivers, but is simpler, cheaper, and smaller, requiring just a quarter of the
detectors used in conventional receivers.
Simplification was achieved by adopting a
coding technique to fibre
access networks that was originally designed to prevent signal fading in
wireless communications. This approach has the additional cost-saving
benefit of using the same optical fibre for both upstream and downstream
data.
“This simple receiver offers users a dedicated wavelength, so user
speeds stay constant no matter how many users are online at once. It can co-
exist with the
current network infrastructure, potentially quadrupling the
number of users that can be supported and doubling the network's transmis-
sion distance/coverage,” added Dr Erk
ı
l
ı
nç.
The receiver was tested on a dark fibre network installed between Tele-
house (east London), UCL (central London) and Powergate (west London).
The team successfully sent data over 37.6 km and 108 km to eight users
who were able to download/upload at a speed of at least 10 Gb/s. This is
more than 30 times faster than the fastest broadband available in the UK,
today.
“BT Openreach recently announced that fibre
access is a key focus and
must improve. With high-capacity broadband a priority for the UK govern-
ment, we will be working to reduce the electrical power requirements of this
technique to make this commercially viable in the nearest future. We be-
lieve that it has real potential to provide high-speed broadband connectivity
95
to every home, which will support the growing digitally enabled economy in
the years to come,” concluded Professor Bayvel.
Materials provided by University College London:
https://www.sciencedaily.com/releases/2017/10/171019101002.htm
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