The traffic of the future metro network will dynamically change not only in volume but also in destination to support the application of virtualization technology to network edge equipment such as cloud edges to achieve cost-effectiveness. Therefore, the future metro network will have to accommodate traffic cost-effectively, even though both the traffic volume and the traffic destination will change dynamically. To handle to this trend, in this paper, we propose a future metro network architecture based on Next-Generation Passive Optical Network Stage 2 systems that offers cost-effectiveness while supporting virtual machine migration of cloud edges. The basic idea of the proposed method is sharing a burst-mode receiver between the continuous-mode transmitters and burst-mode transmitters. In this paper, we show the feasibility and effectiveness of the proposed method with experiments on prototype systems, and simulations for the preliminary evaluation of network capital expenditure.

The λ-tunable WDM/TDM-PON is a promising candidate for next-generation optical access networks since it can provide load balancing between optical subscriber units, power savings, high reliability, and pay-as-you-grow capability. In a λ-tunable WDM/TDM-PON system, the degradation of communication quality caused by wavelength switching should be minimized. The system should also preferably be able to change wavelengths of multi ONUs simultaneously to make wavelength reallocation speed high. The system should also be able to accommodate ONUs whose wavelength tuning times are different. The challenge to meet all three requirements is to suppress latency degradation and frame loss when wavelengths of multi-type ONU are switched simultaneously in WDM/TDM-PON systems. We proposed an OLT architecture and a wavelength switching method that cooperates with traffic control to suppress frame loss and latency degradation by multi-ONU wavelength switching. However, there have been no reports on the impact on latency of downstream and upstream traffic when wavelengths of multi-ONU are simultaneously switched in λ-tunable WDM/TDM-PON. In this paper, we evaluate and analyze the impact of wavelength switching on latency in 40 Gbps WDM/TDM-PON systems. An experiment results show that latency degradation and frame loss are suppressed. Dynamic wavelength allocation operation with 8-ONUs-simulateous wavelength switching in 512-ONUs WDM/TDM-PON system is demonstrated.

This paper reviews next generation optical access network standardization activities, focusing on 10-Gbps class TDM PON, and introduces key technologies for their co-existence with deployed systems.

This paper proposes a power saving mechanism with variable sleep period to reduce the power consumed by optical network units (ONUs) in passive optical network (PON) systems. In the PON systems based on time division multiplexing (TDM), sleep and periodic wake-up (SPW) control is an effective ONU power saving technique. However, the effectiveness of SPW control is fully realized only if the sleep period changes in accordance with the traffic conditions. This paper proposes an SPW control mechanism with variable sleep period. The proposed mechanism sets the sleep period according to traffic conditions, which greatly improves the power saving effect. In addition, the protocols needed between an optical line terminal (OLT) and ONUs are described on the assumption that the proposed mechanism is applied to 10 Gigabit (10G) class PON systems, i.e. IEEE 802.3av 10G-EPON and FSAN/ITU-T 10G-PON systems. The validity of the proposed mechanism is confirmed by numerical simulations.

This paper describes international standardization activities on B-PON, GE-PON, and G-PON. This paper explains their distinctive technologies, and compares them from the technical view. This paper also mentions future PON standards which are discussed in some standardization bodies.