Broadband Forum has released new standards for the modularisation of the Dynamic Bandwidth Assignment (DBA) function, representing a significant advance in the Quality of Service (QoS) of optical access systems and a milestone for 5G by accelerating the time-to-market for time-critical applications.
The specifications define an Application Programming Interface (API) that enables the DBA software module to be replaced. As a result, optical access systems can quickly and cost-effectively provide a wide range of services, including support for 5G fronthaul interfaces and services for business users.
NTT and Chunghwa Telecom have jointly proposed use cases of the DBA software module and developed the API specifications as international standards within the Broadband Forum.
“These technical advances will enable carriers to use a common access system for a diverse range of services including the accommodation of base stations for 5G mobile systems, which place strict requirements on acceptable latency thresholds,” said Jun Terada, General Manager at NTT Access Network Service System Laboratories. “Although DBA, which requires high-speed processing in the region of sub-milliseconds, was thought difficult to modularise due to its time critical nature, it is a crucial function that significantly impacts QoS in optical access systems. We believe that the widespread use of the API as an international standard will lead to the drastic expansion of the application area of optical access systems.”
The new standards – the culmination of Broadband Forum’s PON Abstraction Interface for Time Critical Applications (TCAs) project which was launched by NTT 2017 – consist of two Technical Reports, TR-402 and TR-403. The former provides an overview of the modularisation of the DBA function, including a use case regarding accommodation of base stations for 5G mobile systems over an optical access network, and specifies the functional requirements of the API. TR-403 specifies details of the API, including format and performance requirements.
Prior to this, NTT launched the new concept of Flexible Access System Architecture (FASA), with the target of realising the future access network, and conducted research and design activities on primary technologies and specifications. Alongside this, Broadband Forum intensively developed new architectures, interfaces, and protocols that can disaggregate the functions composing access systems.
In 2018, NTT successfully demonstrated Optical Line Terminal (OLT) modularisation and succeeded in developing and testing OLT prototypes with the API that enables the smooth replacement of DBA software modules to meet new service requirements.
Looking ahead, NTT will modularize the remaining access functions in cooperation with carriers, system vendors, Standards Developing Organizations (SDOs), and Open Source Software (OSS) organisations in order to 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.
“The work completed by NTT and Chunghwa Telecom is essential to meet changing user demands, and we are proud to have had such an important project undertaken within Broadband Forum,” said Robin Mersh, Broadband Forum CEO. “The work fits perfectly with our other initiatives around next-generation access and will enable operators to cost-effectively upgrade their optical access networks as they prepare for the 5G era. We applaud NTT for its innovation and its commitment to feeding this work into new industry-wide standards which will create an open broadband infrastructure and simulate mass deployment.”