NTT Network Innovation Laboratories (NIL), founded in 1999, continues to pursue new innovative IT industries. It integrates a wide variety of researchers ranging from the physical layer to the application layer including the fields of optical, wireless, network, and software technologies. "Mirai-Net," the Japanese name of NIL, stands for "future network," which means pioneering a new era through innovative ideas from a diverse array of researchers.
In the 1980's, the predecessor of NIL was a global R&D leader in digital communication technologies, such as fiber-optics SONET/SDH or microwave-relay communications. In the 1990's, technologies such as wavelength division multiplexing(WDM), asynchronous transfer mode (ATM), and mobile communications made great progress through our research activities. Since the 2000's, we have continually generated brand-new achievements in fields of such as digital coherent transmission, space division multiplexing, network virtualization, edge-computing, wireless LANs and IoT wireless access. By leveraging these accomplishments, we are continuing to generate "innovations."
Research and development of optical communications at NTT Laboratories began in 1976 with a transmission speed of 32 Mb/s, which was increased to 400 Mb/s through the practical implementation of F400M transmission using single-mode optical fiber in 1982. Following this, the use of dispersion-shifted fiber and distributed feedback (DFB) lasers raised transmission speeds to 1.6 Gb/s, 2.4 Gb/s, and 10 Gb/s. At present, NTT is developing practical optical transmission systems featuring speeds of 100 Gb/s and greater. These systems are starting to be deployed.
In long-distance optical transmission, a regenerative relay is needed to receive, shape, and retransmit the signal before it becomes too weak. Although loss in optical fiber is small, signals can drop to 1/100 their original strength over a distance of 100 km preventing them from being received. With this being the case, the Erbium-Doped Fiber Amplifier (EDFA) was developed to amplify light itself within the optical fiber. NTT Laboratories has performed groundbreaking R&D in this area, conducting the world's first long-distance EDFA relay transmission test (1989) and developing the world's first compact, laser-diode-excited EDFA. It also led the way in achieving a practical FA10G system capable of signal transmission over 320 km using only optical amplifiers (1996).
WDM technology increases transmission capacity by simultaneously passing light of different wavelengths (colors) through a single optical fiber. NTT has achieved transmission of 80 wavelengths at 100 Gb/s in a practical system and WDM transmission of more than 1 Tb/s per wavelength in the laboratory.
To achieve flexible allocation and efficient use of wide transmission bands made possible by WDM transmission, NTT advanced the concept of a "wavelength path" that treats each wavelength as a virtual fiber thereby laying the foundation for today's photonic network. As part of this effort, NTT researched and developed an optical Generalized Multiprotocol Label Switching (GMPLS) router that merges IP and optical switches.
Aiming for a large-capacity optical transmission system of the order of 100 Tbps per optical fiber, work proceeds on the research and development of digital-coherent optical transmission technology that can extract to the fullest a key property of optical waves (coherency) through large-scale digital signal processing technology and dramatically improve transmission efficiency. As a key device toward practical implementation, NTT is developing a large-scale Digital Signal Processor (DSP) having more than a hundred million gates featuring ultra-high-speed digital signal processing and low power consumption.
Aiming to overcome existing limitations in single-mode optical fiber (saturation of spectrum efficiency, limits to optical input power) and increase capacity beyond one petabit per second (Pbps) per fiber over a transmission distance of 1000 km or greater, we are researching multicore transmission that arranges multiple cores in a single fiber and multimode transmission that uses multiple transmission modes within a single core. We are also investigating system and component technologies to this end.
Synchronous Digital Hierarchy (SDH) is a standard for high-speed digital transmission using optical fiber. As the word "hierarchy" implies, this standard specifies a mechanism for hierarchically stacking low-speed channels to construct a high-speed, high-reliability network. It has found widespread use as an optical interface in long-distance transmission networks. NTT and other telecom carriers in Japan, United States, and Europe possessing advanced optical communications technologies came together at the International Telecommunications Union (ITU) to draft an international standard for the SDH scheme (1988).
In contrast to the conventional SDH transmission scheme featuring synchronous transmission over the entire network, NTT developed and deployed a transmission system using Asynchronous Transfer Mode (ATM) that enables data of diverse formats typical of the multimedia age to be transmitted efficiently by asynchronous means. By dividing voice, video, and other types of information to be transferred into 53-byte blocks called "cells," ATM meets the high-speed, broadband communication needs in NTT Group services.
To achieve practical broadband services, it is important to broaden the communication bandwidth through evolution of optical transmission technology and to increase the speed of the entire communication system including terminals and applications. To this end, NTT developed technology for performing direct data transfers between the memory units of computer systems thereby eliminating CPU bottlenecks and researched and developed speed-enhancement technology that implements communication protocol processing in hardware.
To transmit highly detailed video as needed in such fields as medical care, printing, and movie production, NTT proposed Super High Definition (SDH) images having four times the spatial resolution and two times the temporal resolution of HDTV and researched and developed a real-time codec and robust IP transmission system for transmitting SDH material. The use of this technology in 4K digital cinema has greatly contributed to the spread of this cinema format. In addition, the error correction code developed for 4K live broadcasts was adopted in the next-generation MPEG Media Transport (MMT) international standard.
To provide services in a flexible and prompt manner and reduce facility and operation costs, R&D proceeds on converting network elements to software through such techniques as Software Defined Networking (SDN) and Network Function Virtualization (NFV). For example, the Lagopus software switch, which is compatible with Open Flow, a popular SDN protocol, achieves high speeds in excess of 10 GbE comparable to hardware switches. In this way, Lagopus will enable dynamic and quick construction of ICT environments tailored to industrial and public infrastructures and to diverse applications including healthcare and disaster prevention.
We are researching and developing technology for reducing latency and optimizing communication traffic by placing computing resources at locations close to things in the real world such as at the network periphery (edge) and dividing up and linking processing among clouds/data-centers and terminals. Edge computing targets the world of IoT applications that require regional processing of large amounts of information as in control processing based on video analysis. We are developing, in particular, a vertical distributed processing platform for advanced use of ICT resources through vertical distributed computing among terminals, the edge, and clouds/data-centers. We are also working on support technologies for efficient development of services to be operated on that platform.
Antennas mounted on mountaintop towers facing in opposite directions are used for microwave transmission. They support information communications in Japan by relaying telephone and television signals. NTT developed and deployed the world's first digital microwave system in 1968 and the world's first microwave system using 256QAM modulation in 1989.
Japan launched its first commercial communications satellite (CS-2) in 1983 representing the world's first deployment of a satellite communications system using the quasi-millimeter band (30/20 GHz). This system provided a stable means of communication with the Ogasawara islands by enabling automatic and immediate calling through satellite circuits thereby completing the implementation of automatic calling throughout the country. In 1995, the N-STAR satellite owned by NTT was launched. This satellite used multi-beam satellite transmission technology that increased the capacity and cost-effectiveness of satellite communications.
Research and development in mobile communications got under way in the second half of the 1950s with an 800 MHz car phone system launched in 1979. Mobile equipment in 1980 was large at a volume of 1500 cc, but in 1989, mobile phones with a volume and weight of 400 cc and 600 g hit the market. Then, in 1990, thanks to progress in miniaturization due to smaller components and the use of LSI chips, NTT developed the mova series of mobile phones that, at 150 cc in size, were the world's smallest and lightest handsets at that time. These features helped to launch the explosive growth of mobile phones. NTT also developed the Personal Handy phone System (PHS) beginning services in 1995. These developments made it possible to call "anytime, from anywhere, and to anyone." Mobile phone and PHS technology developed by NTT was passed on to NTT DOCOMO.
The growth of the Internet made it necessary to provide the wireless access system with broadband capabilities. A typical technology for doing so was high-speed wireless LAN. In 1999, the IEEE802 committee of IEEE, a standardization organization in the United States, approved IEEE802.11a using the 5 GHz band as a standard specification for high-speed wireless LAN. This specification adopted the OFDM radio transmission method based on a joint proposal by NTT and other companies.
There is increasing anticipation for using Low Power Wide Area (LPWA) communication, which can communicate at low speed over wide areas, as a means of wireless access for IoT. We have developed technologies to improve the reliability of LPWA connectivity so it can also be used for control applications, including improving signal arrival and a low power wireless relay technology. The former will help eliminate out-of-range IoT terminals, which unlike people do not generally move, and the latter will enable communication in hard-to-reach areas such as underground.
To enable high-volume content to be used immediately and without stress, we are promoting R&D on radio equipment that uses a compact, highly-integrated millimeter-wave wireless module. We have realized contactless, high-speed millimeter-wave transmission able to transmit gigabit-class high-volume content to portable terminals instantaneously.
We are conducting R&D to further increase the bandwidth of wireless access. This includes R&D on technologies such as Orbital Angular Momentum (OAM) multiplexed transmission, which will dramatically increase wireless communication transmission speeds. We are tackling technical issues with the goal of realizing Terabit-class wireless transmission.
To provide new value by enabling observation and measurement of the unseen, we are promoting R&D on basic technology to implement wireless access in unexplored areas. We are engaging in R&D to further expand coverage into areas such as under water, in the air, and in space.