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The passive optical network (PON) is widely deployed in access networks, and various specifications have become standards designed to meet demands of each market. To accelerate new PON-based service creation, software-defined network enabled broadband access (SEBA) is being studied; it uses a common API to abstract various optical line terminal (OLT)/optical network units (ONUs) and manages the devices via a controller. However, the current abstraction unit in SEBA supports only ITU-T PON. In order to support IEEE PON, multiple package types and switching management functions must be considered. This paper proposes a technology profile including package types for IEEE specification and an adapter that abstracts IEEE PON and switches functions according to the specified package type. The logical link configuration settings for ITU-T PON and IEEE PON are implemented in common, and the adapter abstracts IEEE PON OLT/ONU by switching between extended operation, administration, maintenance (eOAM) functions for package B and other eOAMs. We demonstrate the proposed software on a system implemented using commercially available OLT/ONU and OSS in SEBA. The results show that OLT/ONUs can be managed via a common API, differences in package types can be abstracted by technology profiles and our adapter, and that a common SEBA platform can manage, in a unified manner, both ITU-T PON and IEEE PON.

This article proposes a novel architecture of a time division multiplexing passive optical network (TDM-PON) system with general-purpose hardware. The system operates with the point-to-point (P2P) Ethernet protocol and software processing. The architecture is redesigned from the ground up, differing from conventional PON system architectures. In recent years, researchers have attempted to softwarize a number of PON functions such as media access control (MAC) and physical functions, which run on a general-purpose central processing unit (CPU). On the other hand, these existing systems still required PON-dedicated or programmable hardware for processing the PON specific protocol. This paper proposes a TDM-PON system that requires only general-purpose hardware; a network interface card with the use of the P2P Ethernet protocol and a general-purpose server with the use of software processing. To operate the proposed system, we newly developed burst-mode operation and multipoint MAC control schemes, while taking Link Fault Signaling and CPU processing jitter into account. We quantitatively evaluated the burst-mode transmission with P2P generic Ethernet TRx as a preliminary experiment, which showed that Ton and Toff were 75 μs and less than 1 μs, respectively. Then, we measured our developed prototype system's performance for verifying the feasibility of our proposal. In specific, it achieved a 5.2 Gbps PON system consisting of an optical line terminal (OLT) server and two optical network unit (ONU) servers under the condition of a 500-ms grant cycle including a 100-ms discovery window.

This paper summarizes our studies on the flexible access system architecture (FASA), which will support a wide range of services and stimulate the creation of new services in the next generation. After reviewing related concepts and technical trends, FASA's concept and use cases are introduced. FASA aims to cover residential, enterprise, and mobile backhaul/fronthaul services. The technical directions associated with implementing FASA and the challenges raised are described. They include hardware design to maximize the use of common hardware, clarification of architectures that suit time-critical applications, and deeper softwarization.

This paper shows the concept of the elastic lambda aggregation network (EλAN) that will achieve an elastic common access infrastructure for the metro-access network. It proposes a service restoration technique that uses optical path switching and intercentral office handover for EλAN to recover from disasters. The feasibility of the proposed service restoration technique is successfully demonstrated for the first time by using a prototype testbed of a metro-access network. By applying both orthogonal frequency division multiplexing and adaptive modulation, the system automatically changes the transmission parameters (modulation level, the number of subcarriers, and symbol rate) according to the service requirements and conditions of the optical distribution network, such as the link's end-to-end optical loss, in order to achieve accommodate multiple services. In the experiment, an optical network unit in a faulted system automatically reconnected within 10 s to another office 20-km away with the same throughput.

Passive optical networks (PONs) are widely deployed worldwide as access networks, and various standards have been created to serve the demands of different markets. In recent years, software-defined-network-enabled broadband access (SEBA) has been studied for the realization of flexible and cost-effective PONs, while the zero touch provisioning (ZTP) function of optical line terminals (OLTs) and optical network units (ONUs) is being studied for automatic management. However, although ZTP for ITU-T standards has already been implemented, ZTP for IEEE standards has not been achieved, since the workflow is significantly different for each access standard due to differences in the authentication method. The subdivided package specifications and medium access control (MAC) dress authentication are barriers that hinder achieving ZTP for the IEEE standards. This paper proposes a workflow driver based on a model that implements authentication compliant with IEEE PON packages A and B according to events produced by SEBA components and specification information obtained from OLT profiles. The feature of our proposal is to fabricate an IEEE-compliant driver package that automatically switches the authentication method by acquiring the technology profile of the orchestrator, and as soon as IEEE802.1X authentication or MAC address authentication is completed, the subscriber setting is registered to the SDN controller in order to enable data plane service. We demonstrate the proposed workflow driver on a system consisting of SEBA-focused commercially available OLT/ONU hardware and open source software. The results show that the orchestrator can automatically provision ONUs and that managing various access devices on a common access platform is feasible.

This paper presents the world's first field trial of a 40-km reach and over 512-split symmetric-rate 40-Gbit/s λ-tunable time and wavelength division multiplexing passive optical network (TWDM-PON) that utilizes our newly developed high-speed λ-tunable optical network unit transceivers and automatic gain controlled semiconductor optical amplifier-based PON extender for repeater and central office use. The upstream signals for C-band and downstream signals for L+-band in our developed λ-tunable TWDM-PON comply with the wavelength plan of ITU-T G.989 series. In a field trial, we successfully demonstrate error free λ-tunable transmission for the 40-km reach and 1024-split (maximum number) symmetric-rate 40-Gbit/s λ-tunable TWDM-PON over installed standard single-mode fiber links, and advanced network functions such as dynamic load balancing, incremental system upgrade, optical subscriber unit protection, and OLT equipment power saving are also confirmed.

The dis-aggregated passive optical network (PON) optical line terminal (OLT) architecture is attracting attention in academia and industry. This paper first reviews the evolution in dynamic bandwidth allocation (DBA) dis-aggregation. We further enhance the scalability of the dis-aggregated PON-OLT by reducing the bandwidth overhead of REPORT/GATE, the time division multiplexing (TDM) control information transferred between dis-aggregated DBA and the hardware platform. Our experiment verifies that the data compression based on basic integer coding can improve the scalability by 27% with acceptable processing time.

This paper summarizes our studies on the Flexible Access System Architecture (FASA) which will support a wide range of services and stimulate new services in the next generation; its overview and technical challenges are described.

The first demonstration of the service restoration technique for metro-access networks successfully shows that ONU accommodated by the disaster-stricken central office is automatically reconnected within 10 sec to another office 20-km away with the same throughput as before disaster.

We propose a dynamic subcarrier allocation algorithm based on transmission parameters and traffic conditions. Real-time demonstration confirms that our algorithm can greatly improve fairness of frame loss rate among ONUs compared to fixed subcarrier allocation.