Researchers at Fujitsu have achieved 100 Gbps optical transmission by running Discrete Multi-Tone (DMT) modulation/demodulation on digital signal processors (DSPs) originally intended for 10 Gbps per channel rates.
The DMT modulation/demodulation format, which is used in xDSL, divides the data into multiple subcarriers (carrier waves), and multi-level modulation is used for each subcarrier to achieve high transmission speeds. To optimize each subcarrier’s power and number of multiple values, an algorithm was developed that checks receiving conditions between optical transceivers at the time the system is started up and optimizes power and the number of multiple values to suit the transceivers and line conditions.
Fujitsu said this approach could be scaled up to achieve 400 Gbps Ethernet transceivers suitable for data center applications.
http://www.fujitsu.com/global/news/pr/archives/month/2013/20130314-02.html
