Wavelength Switching Method that Cooperates with Traffic Control for λ-Tunable WDM/TDM-PON

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.