World's First Demonstration of Modularization of Dynamic Bandwidth Assignment; Crucial Function to QoS in Optical Access System

- To Achieve Future Optical Access Systems Quickly to Provide Various Services in 5G Era -

TOKYO, Nov. 21, 2018 /PRNewswire/ -- Nippon Telegraph and Telephone Corporation (hereinafter "NTT") headquartered in Tokyo has developed a prototype of an optical line terminal (OLT) with a softwarized and modularized dynamic bandwidth assignment (DBA (*1)) function, which represents a significant impact on the quality of service (QoS) in optical access systems (e. g. FTTH; Fiber to the Home). The prototype successfully supports, for the first time, the replacement of the DBA software module to meet changes in service requirements. This advance enables carriers to use a common access system for a diverse range of services including accommodation of base stations for the fifth generation (5G) and beyond 5G mobile systems.

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NTT has already introduced the FASA (*2) (Flexible Access System Architecture) concept, and tried to modularize the functions essential to access system operation. Although DBA is well known to be one of the most difficult functions to modularize because of its timing-critical feature, NTT has succeeded in modularization by dividing it into a software part that is replaced to suit the service requirements, and a hardware part independent from the requirements. Furthermore, an API (*3) (Application Programming Interface) that facilitates the cooperation and control of the two parts is introduced. Combining this approach with low-latency optical access technology (*4) offering coordination with 5G mobile systems will yield optical access systems that can be quickly altered to realize various new services in the 5G era. In addition to the DBA function, continued modularization of other various functions and the replacement of software components will avoid the significant investment of redeveloping hardware-level equipment from scratch. This will result in cost-effective access systems that can quickly meet various requirements.

In order to establish the API as open specifications for use by various partners, NTT is currently working to advance standardization activities in the Broadband Forum. NTT will push forward its R&D activities which are even now contributing to the expansion of the application area of optical access systems in cooperation with other carriers, system vendors, standardization organizations, and open source software development organizations.

The accomplishments will be presented at NTT R&D Forum 2018 (Autumn) (*5) and an international exhibition on network virtualization technologies, ONF CONNECT (*6).

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(*1) DBA Dynamic Bandwidth Assignment. This is a dynamic bandwidth control function for point-to-multi-point optical access networks. In order to avoid the collision of upstream data from multiple ONUs, the DBA function in an OLT assigns times to each ONU at which to start upstream transmission and the transmission duration.

(*2) FASA Flexible Access System Architecture. "Introducing the New FASA Concept for Future Access Systems" -- NTT news release February 8, 2016 FASA Home page: []

(*3) API Application Programming Interface. This is an interface that specifies how components should interact.

(*4) Low-latency optical access technology "Development and trial of low-latency optical access technology that operates in coordination with a 5G mobile system" -- NTT news release February 14, 2018

(*5) NTT R&D Forum 2018 (Autumn) To be held November 29 to 30, 2018, at the NTT Musashino R&D Center (Musashino, Tokyo).

(*6) ONF CONNECT To be held December 4-6, 2018 (Santa Clara, United States of America).

FASA is a registered trademark of NTT.

CONTACT: Rie Ogawa, Public Relations, Planning Department, NTT Information Network Laboratory Group, Tel: +81-422-59-3663, Email:

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