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NTT Network Innovation Laboratories


The NTT Network Innovation Laboratories was established in 1999 and gathers a wide range of researchers conducting research that contributes to creating new communications industries in areas such as optical, wireless, networks, and software technologies, and ranging from the physical to the application network layers. In the Japanese name for the organization, "Mirai NET", expressing the aim of the laboratories, to "Contribute to a new era of communications through the free creativity and activities to stretch current capabilities of a diversity of researchers."

Within the organization, the technology and experience gained in each of these fields through many years of NTT R&D is continuously carried forward.

Development of the Network Innovation Laboratories

When "Digitization of communication" was the goal during our INS concept period, the lab was producing leading-edge, practical developments in areas including fiber-optic and microwave relay transmission. Also, technologies we addressed in the VI&P conception period, when we were promoting our "21st Century Services Vision", are now in full bloom, such as SDH/SONET transmission protocols, WWW, and mobile phones. Further, in our Mega-media concept period, we conducted leading-edge R&D in technologies that are now indispensible in modern society, such as amplified optical relay, wavelength-division multiplexed (WDM) transmission, FTTH, and wireless LAN.

Even today, we are still focusing this technology and experience to advance R&D on new means of communication that will revolutionize daily life.



■Fiber-optic transmission

Optical fiber is capable of communications with higher volume over longer distances than coaxial cable because it has higher bandwidth and produces lower losses. Research on optical transmission at NTT laboratories began in 1976 with transmission at 32 Mbps, and by 1982 we had achieved F400M transmission at 400 Mbps using a single-mode optical fiber. Later, speeds were increased to 1.6 Gbps, 2.4 Gbps, and 10 Gbps using dispersion-shift fiber and DFB lasers, and currently we are conducting R&D on optical transmission systems capable of 40 Gbps and higher, and these are starting to be introduced.

■SDH/SONET (Synchronous Digital Hierarchy / Synchronous Optical NETwork)

A standard for high-speed digital transmission using optical fiber. As suggested by the word "hierarchy" in the name, it is a scheme in which low-speed channels are aggregated in levels, allowing high-speed networks with excellent reliability to be built. It is widely used as the optical interface for long-distance communications networks. NTT and other communications operators in Japan, U.S. and Europe that have state-of-the-art optical communications technology gathered together with the International Telecommunications Union (ITU) and produced the SDH international standard (1988). Note that the ITU discussion is also reflected in the American SONET standard, which was created in parallel, and the two standards are effectively the same.

■Amplified optical relay transmission

Transmitted signals become weaker as they propagate, so for long-distance transmission, a regenerative relay is needed. Such a relay receives, corrects and retransmits the signal. Losses are low with optical fiber, attenuating by only 5% over 1 km, but this results in signals reduced to 1/100 or less over a distance of 100 km, so eventually they are too weak to receive. However, transmission distances can be extended if the light can be simply amplified. The Erbium-Doped Fiber Amplifier (EDFA) is an optical amplifier developed for this purpose. It uses optical fiber as an amplifying medium through addition of the element erbium. NTT Laboratories have lead with pioneering R&D in this area, including conducting the world's first long-distance EDFA relay transmission test (1989), developing the world's first compact, laser-diode-excitation EDFA, and implementing the FA10G scheme, capable of transmitting over 320 km using only optical amplifiers (1996). This is currently one of the main technologies supporting data communications in Japan.

■WDM transmission (Wavelength Division Multiplexing)

WDM is a technology for increasing transmission capacity by transmitting different wavelengths (colors) of light on a single optical fiber at the same time. NTT has implemented transmission of 80 wavelengths at 10 Gbps, and in the laboratory, has achieved simultaneous transmission of over 1,000 wavelengths. Controlling 1,000 lasers in parallel is a difficult task, so we are also developing a single laser able to emit 1,000 or more wavelengths at a time. We are also advocating a "wavelength path" concept which portrays each wavelength as a virtual fiber. This will be used to build a base for current photonics networks. We are also conducting R&D on an optical GMPLS router that unites IP and optical switching and other devices.

■Optical access

Also called fiber-to-the-home (FTTH), this refers to the provision of high-speed access lines to users using optical fiber. Researchers associated with the Network Innovation Laboratories have conducted practical testing since 1992, refining this technology. Optical access began in 2001 with the B-Flets service, and the technology developed at the time persists. NTT announced plans to have 30 million subscribers using FTTH by 2010 and is racing toward realization of a full-fledged, "optical society".

Infrastructure, software

■Artificial intelligence

In the past, in this field we focused on creating network expert systems for distributed environments connecting computers to networks, or games like shogi (Japanese chess) and go. We also developed a sophisticated artificial intelligence workstation from a basic research level to a commercial product. This workstation was for use in artificial intelligence research itself, and also as an environment for development and execution of artificial intelligence applications. Recently, we are also conducting R&D on a multi-agent system that is able to interact with the real world, through the coordinated action of multiple agents created for individual sensors and actuators.


At the dawn of the Internet age in 1984, we quickly connected with USENET in the USA and implemented a computer network environment. At that time, the NTT domain name was, and this was used for email and Web pages until it expired in July 1998. We have also proposed a distributed-parallel, object-oriented language for use in development from the network layer to the middleware application level. The language enables programs that cooperate across separate computing systems to be coded without concern for the distributed aspect of the code. In 2001, we developed the world's first system spanning multiple Internet Service Providers (ISPs) and able to automatically diagnose network path faults. This was installed on the OCN service operated by NTT Communications, starting in April 2004.


In December 1993, more than a year before June 1995, when NTT announced its "Basic Multimedia Plan" and adopted a proactive stance toward the Internet, some young researchers independently set up an NTT Web site ( At the time, it was the most popular Web site, with the most page views. Then, for one year starting in April, 2001, we operated an experimental search engine Web site. From the search history obtained in this experiment, we analyzed the structure of the Web space and advanced R&D on effective information search and provision technology within such an enormous information space.


■Microwave relay

The multiple antennas seen mounted facing in opposite directions on towers near the tops of mountains are for microwave transmission. They are used for relaying telephone calls and television signals, supporting data communications in Japan. NTT developed and implemented the world's first digital microwave system in 1968, and the world's first system using 256QAM modulation in 1989.

■Satellite transmission

In 1983, Japan launched its first commercial communications satellite, CS-2, and it was the world's first implementation of a satellite using the quasi-millimeter band (30/20 GHz). It also achieved a stable means of communication with the Ogasawara islands. Till that time, long distance calls between the Ogasawara islands and the mainland were all by short-wave radio, and took an average of ten minutes to connect after contacting the switchboard. With satellite lines, connection became immediate and automatic, and calls to the mainland could be dialed directly. This development completed implementation of immediate calling throughout Japan. In 1995, the N-STAR satellite owned by NTT was launched. It uses multi-beam satellite transmission technology, increasing the capacity of satellite communications and making it more economical. Currently satellite communications is used to increase network reliability, and for disaster mitigation. In activity recovering from the Great Hanshin-Awaji Earthquake in Kobe, the communications provided by approximately 70 specially installed public phones were provided via satellite. We are currently advancing R&D on infrastructure to implement broadband for mobile satellite communications.

■Mobile phones/PHS

Our R&D on mobile communications began in the latter half of 1950, and in 1979, we implemented an 800 MHz-band automobile phone. Mobile phones in 1980 were large, with a volume of 1500 cc, but by 1989 this was reduced to 400 cc and 600 g. With LSI and decreases in size of all parts, this decreased dramatically to 150 cc with development of the mova, the smallest and lightest in the world at the time. These developments lead to the explosive growth in the mobile phone market. Also, in response to demand from users to take cordless phones with them outside the home, the Personal Handy-phone System (PHS) was developed and services began in 1995. This made it possible to call "anytime, from anywhere, and to anyone." Mobile phone and PHS technology was taken over by NTT DOCOMO.

■Wireless access

As the Internet continues to spread, users increasingly demand easy network access as the need arises without regard to time or place. Broadband wireless access systems are needed to provide this. One typical technology for providing such systems is high-speed wireless LAN. In 1999, the IEEE 802 committee, which is an American standards organization, released the IEEE802.11a standard for high-speed wireless LAN using the 5 GHz band. This specification adopted a wireless transmission technology called OFDM, which is based on joint proposals by NTT and other companies. We are currently advancing R&D to further increase the bandwidth of wireless access methods like wireless LAN and to develop infrastructure for achieving ubiquitous wireless networking.

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