Vol.5 No.1 (February, 2010)

Special Issue on Optical Submarine Cable System

Fundamental Technologies and Devices

INOUE Takanori

As one of the foundations of the global network, the submarine cable system is required to achieve large-capacity transmissions of the Tbps class and long-distance transmissions at the transpacific level and both of these at high quality. This paper describes the technology for achieving long-distance transmissions and the associated efforts being applied by NEC.

YAMAGUCHI Shohei ・MIKAMI Satoshi ・AIDA Ryuji ・NAGASAWA Toshihide

The key to meeting the increasing needs of submarine cable systems (increase in capacity, increase in distance, multipoint connections, etc.) is how to incorporate and implement designs for optical submarine repeaters, gain equalizers and the branching units installed in the submarine sections. This paper introduces the functions of different types of equipment and the technologies applied to them.

NISHIDA Takato ・NAGATOMI Osamu

This paper describes the technical features and characteristics of the OCC-SC300 cable as used in the latest optical submarine cable systems. It also introduces DMF optical fiber, as applied to recent ultra-long distance D-WDM systems. In addition, a sea trial conducted for the integrated evaluation of the final stage of development of the OCC-SC300 cable is reviewed.

SATO Yoshiro ・NAKADA Tatsuhiro

The global growth of IP data traffic has been driving the need for increasing the capacities and transmission distances of optical submarine cable systems year by year.This paper introduces the features and configurations of the T640SW LTE optical submarine cable system terminals. This equipment features an ultra-large transmission capacity of 1.32 Tbps (10 Gbps transmission speed × 132 waves) and an ultra-long transmission distance of over 9,000 km.

KANEKO Tomoyuki ・CHIBA Yoshinori ・KUNIMI Kaneaki ・NAKAMURA Tomotaka

A submarine cable system is fed power from power feeding equipment that supplies constant current. Such power feeding equipment is expected to enable an ultra-high voltage output to supply power for long-distance submarine cable systems, as well as supporting long-period operations. This paper introduces power feeding equipment for application to NEC’s submarine cable systems that achieves compact, high voltage and high reliability characteristics.

NOMURA Kenichi ・TAKEDA Takaaki

The introduction of large-capacity wavelength-division multiplexing and OADM (Optical Add/Drop Multiplexing) technologies in optical submarine cable systems has led to an increase in the number of stations and complications in system configurations with regard to the necessity for connection management per wavelength band, etc. This trend has increased the need for submarine monitoring equipment that can control an entire network by crossing over the barriers of traditional management systems. This paper describes the requirements of operations management systems that are capable of dealing with complicated optical submarine networks together with discussion of some of NEC’s solutions.

MIWA Daiki

Following the expansion of IP networks led by a rapid increase in recent data traffic, the needs of SLTE (Submarine Line Terminal Equipment) used in optical submarine cable systems are being diversified. In order to meet this trend, NEC has developed the integrated optical terminal equipment based on MSP (Multi-Service Platform) and is applying this solution to various systems. This paper introduces the features and achievements of the integrated optical terminal equipment and its future development prospects together with trends in the market environment that surrounds it.

Systems and Construction Technologies

YONEYAMA Kenichi ・SAKUYAMA Hiroshi ・HAGISAWA Akira

In terms of capacity, distance and number of connecting points, the requirements for submarine cable systems have been increasing every year. The key to the implementation of the most advanced ultra-long distance transoceanic submarine cable system of large capacity lies in how to introduce and apply the latest optical signaling technology to the actual systems design and construction. This paper introduces the construction technologies that are being applied to large-capacity, ultra-long distance submarine cable systems from the perspectives of system design, equipment fabrication, system assembly and system construction.

OHTA Tsutomu ・NISHIYAMA Tomohisa

Submarine cable systems will carry traffic for long-term over 25 years after entered into service. In order to construct a submarine cable system that can withstand for such a long period of time, it is required to conduct a marine route survey to identify the condition of the seabed in which the system is to be installed and to design the cable route based on the survey results. The assembled cable system is installed by a cable ship between the terminal stations to configure a communication system. This paper introduces how a submarine cable system installation is implemented by following the project flow step by step.

INADA Yoshihisa

The recent increased traffic accompanying the rapid dissemination of broadband communications has been increasing demand for the optical submarine cable systems that form the backbones of international networks. Considering the capability of the repeaterless optical submarine cable system to significantly reduce construction costs compared to the repeatered optical submarine cable system, an increase in the span length of repeaterless submarine cable systems should be regarded as an extremely important research topic.This paper introduces NEC’s long span repeaterless optical cable system technologies, describes the latest repeaterless terminal equipment and puts forward ideas for the direction of future trends.

FUJIWARA Noriyuki ・HISHIKI Kenji ・KATAYAMA Takeshi

Since the first offshore installation at Omaezaki, Shizuoka-ken, in August 1978, a total of eight “cable-based” ocean-bottom seismographic observation systems (In-Line type systems) have been installed for use in the real-time observation of earthquake and tsunami data on the Pacific side of the Japanese Archipelago. These systems are applying a digital communication technology and a high reliable technology of the submarine cable system. On the other hand, development of the “NODE type system” featuring two dimensional observations by seismometer and tsunami sensors deployed planarly was started in the USA, Japan and European countries around the year 2000. This paper introduces the technologies applied to the earlier In-Line type systems as well as outlining the most advanced system technologies used in the currently deployed NODE type systems.