Nokia Bell Labs (NYSE:NOK), Deutsche Telekom T-Labs and the Technical University of Munich say they have achieved 1 terabit per second (Tbps) transmission capacity over fiber in a field trial with a new modulation technique.
As part of the Safe and Secure European Routing (SASER) project, the experiment over a deployed optical fiber network of Deutsche Telekom achieved a net 1 Tbps transmission rate, close to the theoretical maximum information transfer rate of that channel and thus approaching the Shannon Limit of the fiber link.
The Shannon Limit was discovered in 1948 by Claude Shannon, Bell Labs pioneer and the "father of information theory."
The trial of the new modulation approach, known as Probabilistic Constellation Shaping (PCS), uses quadrature amplitude modulation (QAM) formats to achieve higher transmission capacity over a given channel to improve spectral efficiency.
PCS modifies the probability with which constellation points - the alphabet of the transmission - are used. Traditionally, all constellation points are used with the same frequency. PCS uses constellation points with high amplitude less frequently than those with lesser amplitude to transmit signals that, on average, are more resilient to noise and other impairments. This allows the transmission rate to be tailored to fit the transmission channel, delivering up to 30% greater reach.
Nokia Bell Labs will present the results of this joint experiment at the European Conference on Optical Communication (ECOC) 2016 in Dusseldorf, Germany on Sept. 19.