Contents

The Prize of the Commissioner of the Japan Patent Office, 2012 National Commendation for Invention
"Efficient Mapping and Time Division Multiplexing for Large Capacity Optical Transport Networks" (PAT. No. 3529713)

[Summery]

This invention is related to high-speed and large capacity optical transport networks (OTNs) where a high volume of communications traffic is transmitted across a long distance. Since the middle of 1990s, broadband services have rapidly proliferated, leading to the massive communications traffic to be transported. In order to meet the demand to transport such massive amounts of traffic, network operators require Dense Wavelength Division Multiplexing (DWDM) based high-speed optical transport networks having the bit-rate of higher than 10 Gbit/s per channel, which was the fastest at that time. Furthermore, various types of data communication services as well as traditional telephone services have emerged with the penetration of the Internet. The technological issues of efficient mapping and time division multiplexing have become crucial to support such various communication services.

The inventors had foreseen the issues to be apparent in the future at an early stage. They invented a digital frame format for next generation high-speed and large capacity OTNs, including the function of Forward Error Correction (FEC) that improves the signal quality because the signal quality deteriorates with an increase in the bit-rate and the function of frequency justification that enables transparent multiplexing of various communication service signals (Fig.1).

The International Telecommunication Union – Telecommunication (ITU-T) standardized this new digital frame format that is partly covered by this invention as the international standard "OTN" (G.709), which is suitable for achieving high-speed optical transmission at the bit-rate of 40 Gbit/s/ch or more. Subsequently, the standard facilitated development of technical components and systems. For example, the OTN-framer LSI for processing the OTN digital frame format was commercialized in 2006 (Ph.1), driving the market of 40 Gbit/s based DWDM systems, and 40 Gbit/s/ch transport service were initiated in Japan in 2007.

Currently, this invention is considered as an indispensable technology for the infrastructure that supports our current broadband society, where OTN deployment activities can be seen among the variety of network operators in the world. In the near future, the deployment of 100 Gbit/s/ch OTN is anticipated, where this invention will continuously contribute to society.