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Information contained in this news release is current as of the date of the press announcement, but may be subject to change without prior notice.
April 25, 2017
Nippon Telegraph and Telephone Corporation
Oki Electric Industry Co., Ltd.
KDDI Research, Inc.
Furukawa Electric Co., Ltd.
Elastic access-metro integrated network that flexibly changes the transmission speed and optical frequency bandwidth towards future multiple services accommodation beyond 2030
Nippon Telegraph and Telephone Corporation (NTT, Chiyoda-ku, Tokyo, CEO: Hiroo Unoura), Hitachi, Ltd. (Hitachi, Chiyoda-ku, Tokyo, President & CEO: Toshiaki Higashihara), Oki Electric Industry Co., Ltd. (OKI, Minato-ku, Tokyo, President Shinya Kamagami), Keio University (Keio, Minato-ku, Tokyo, President Professor Atsushi Seike), KDDI Research, Inc. (KDDI Research, Fujimino-shi, Saitama, president, CEO: Yasuyuki Nakajima) and Furukawa Electric Co., Ltd. (Furukawa Electric, Chiyoda-ku, Tokyo, President: Keiichi Kobayashi) have jointly challenged the advanced future network for 2030 and beyond by conducting innovative studies on "Elastic Lambda Aggregation Network (EλAN*1)".
EλAN sets an adaptive modulation*2 OFDM*3 transmission system, which leads to the significant improvement of optical frequency utilization efficiency, into the access (subscriber's home-central office)-metro (central office-central office) network that directly connects the subscriber's home and the metro central offices via fibers and WSSs*4. Therefore, EλAN provides flexible assignment of the transmission speed and optical frequency bandwidth to support diversified services with different types of traffic, such as internet, enterprise line, and mobile services.
We demonstrated the reliability of EλAN through a prototype testbed network which utilizes optical path provisioning and switching technologies. The demonstration successfully showed, for the first time, that the service accommodated in the failed office was automatically re-connected within 10 sec to another office some 10km away with the same transmission speed as before the failure. The project accomplishments will be presented at an international conference on optical communications, iPOP2017 (The 13th International Conference on IP + Optical Network 2017: Kawasaki-city, Kanagawa, Japan: June 1-2, 2017).
This research and development project was contracted with the National Institute of Information and Communications Technology (NICT) of Japan under a research contract titled "Research and development of elastic lambda aggregation network."
Along with the wider penetration of FTTH (Fiber to the Home) services, efficient operation of a large number of network sets is essential in recent optical access networks. Moreover, the future access network must support, in addition to conventional FTTH service, multiple access services, such as mobile, high-definition video and IoT (Internet of Things) services.
Until now, multiple access services have been provided using distinctly different network infrastructures to meet the disparate service requirements. However, to provide them more efficiently, all services should coexist on the same service-adaptive network that can flexibly meet individual service requirements. If multiple access services share an optical fiber network, high reliability is essential so that the network can keep providing services by autonomous reconfiguration of the network resources*5 remaining after a disaster. Furthermore, high optical frequency utilization efficiency (transmission rate per unit of optical frequency) should also be provided to accommodate a large number of services and subscribers.
From this background, as advanced research studies targeting beyond 2030, the six institutions (NTT, Hitachi, OKI, Keio, KDDI Research, and Furukawa Electric) have been researching EλAN, a service adaptive access-metro network that provides multiple services with high reliability and high optical frequency utilization efficiency.
In conventional access networks, the central office equipment (OLT) is located at access central offices close to subscribers' homes. EλAN, on the other hand, transfers the OLT to a metro central office that aggregates the traffic of metro networks, as shown in Fig.1. Moreover, EλAN improves the reliability of access-metro networking, which will need to accommodate a huge number of subscribers, by using WSSs to switch optical paths flexibly. This innovative architecture offers lower end-to-end latency and power consumption, since Optical-Electrical-Optical (O-E-O) conversion in the access central office is not needed.
EλAN employs a digital coherent*6 OFDM system with adaptive modulation, a technique that can realize dramatically high optical frequency utilization efficiency and large-scale flexible service allocation by using the elastic control of transmission speed and optical frequency bandwidth. In addition, EλAN applies the world's first dynamic bandwidth allocation algorithm in OLTs. This makes it possible for the users to share the additional bits in a fair manner regardless of optical distribution network (ODN) conditions.
The jointly developed EλAN consists of six basic technologies as follows.
To validate the reliability of EλAN with the above six basic technologies, we conducted protection experiments assuming a metro central office failure with total span length of up to 40 km, 10 Gbps/ channel and 512 ONUs accommodated in an OLT (Fig. 8). The demonstration successfully showed, for the first time, that the service accommodated in the failed office was automatically switched to another office some 10km away in real time with the same transmission rate as before the failure; the switching time was short, less than 10 sec (Fig. 9 and 10).
We will work to enhance the maturity and the reliability of basic technologies for EλAN, and will carry out further development activities.