Date: 21/09/2010

New digital signal processing algorithm from Fujitsu to compensate signal distortion over long distances

Fujitsu has developed a digital signal processing algorithm that compensates for waveform distortion in signals sent over hundreds of kilometers of fiber-optic lines, as part of a long-haul transmission system. Fujitsu says that they have also reduced the size of the required circuitry by approximately 70%. The release states that this advance will usher in long-haul fiber-optic transmission systems transmitting data at a rate of over 100 Gbps per wavelength at a lower cost than conventional 10 Gbps systems.

The new signal-processing algorithm used the following developments:
1)The new approach takes into account adjacent intervals, and this approach has been found to allow for fine-grained and accurate compensation using fewer circuit stages. This has been implemented using weighted-average processing.
2)The Fujitsu team's development included the ability to automatically determine the ideal weighting at the receiver based on the characteristics of the incoming wave.

Some of this research was conducted as part of the "Universal Link Project R&D" sponsored by National Institute of Information and Communications Technology (NICT, Japan).

The release says that this technology was employed in an experiment to transmit a 112 Gbps signal over 1,200 km. The signal quality using the new five-stage circuit was found to be comparable to that resulting from a conventional 20-stage circuit. By reducing the circuit size, it will be possible to commercialize the technology using 28-nm CMOS process technology, which is expected to be widely used by around 2013. By contrast, using existing technologies, it is anticipated that it would have been challenging to commercialize in less than 10 years.

This technology will allow ultra-high-speed networks using fiber-optic lines to be constructed at lower costs. This would enable, for example, high-definition 3D video to be accessed from anywhere in the world, as well as advanced distance learning and remote medicine technologies