21st September 2016
1 terabit per second achieved in optical fibre trial
Terabit-per-second data transmission using a novel modulation approach in optical fibre has been announced by researchers in Germany.
Nokia Bell Labs, Deutsche Telekom T-Labs and the Technical University of Munich have achieved unprecedented transmission capacity and spectral efficiency in an optical communications field trial with a new modulation technique. This breakthrough could extend the capability of optical networks to meet surging data traffic demands in the future.
Their research has shown that the flexibility and performance of optical networks can be maximised when adjustable transmission rates are dynamically adapted to channel conditions and traffic demands. As part of the Safe and Secure European Routing (SASER) project, the experiment over a deployed optical fibre network achieved a net 1 terabit (TB) transmission rate. This is close to the theoretical maximum information transfer rate of that channel and thus approaching the Shannon Limit discovered in 1948 by Claude Shannon, the "father of information theory."
The trial of this novel modulation approach – known as Probabilistic Constellation Shaping (PCS) – uses quadrature amplitude modulation (QAM) formats to achieve higher transmission capacity over a given channel, to significantly improve the spectral efficiency of optical communications. PCS modifies the probability with which constellation points (the alphabet of the transmission) are used. Traditionally, all constellation points use the same frequency. However, PCS cleverly uses constellation points with high amplitude less frequently than those with lesser amplitude, sending signals that are overall more resilient to noise and other potential disruption. This allows the data transmission rate to be tailored to ideally fit the transmission channel, delivering up to 30% greater reach.
This research is a key milestone in proving that PCS could be used in the future to improve optical communications. With 5G wireless technology forecast to emerge by 2020, today's optical transport systems must evolve to meet the exponentially growing demand of network data traffic, increasing at a cumulative annual rate of 100%. PCS is now part of this evolution, allowing increases in optical fibre flexibility and performance that will move data traffic faster and over greater distances without increasing the network complexity.
Marcus Weldon, President of Nokia Bell Labs and the Chief Technology Officer, commented: "Future optical networks not only need to support orders of magnitude higher capacity, but also the ability to dynamically adapt to channel conditions and traffic demand. Probabilistic Constellation Shaping offers great benefits to service providers and enterprises, by enabling optical networks to operate closer to the Shannon Limit to support massive datacentre interconnectivity and provide the flexibility and performance required for modern networking in the digital era."
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