Flexible wavelength and dynamic bandwidth allocation for NG-EPONs

Next-generation Ethernet passive optical networks (NG-EPON) allow optical network unit (ONU) transmission scheduling concurrently on multiple wavelengths. This increases the network capacity up to 100 Gb/s and increases flexibility, as four wavelengths are used with an individual capacity of 25 Gb/s. However, an optimum dynamic bandwidth allocation (DBA) is required for a spectrally efficient NG-EPON (100 G-EPON). This paper proposes an online gated service DBA algorithm for NG-EPON to assign a flexible number of wavelengths and a dynamic grant size on each upstream wavelength. The assignment is based on the difference between the start time of the wavelengths and the effectiveness in reducing delay by transmitting on multiple wavelengths. Moreover, to evaluate the transmission effectiveness, an optimum criterion alpha is introduced in relation to the number of ONUs in the network. The proposed DBA algorithm's performance is evaluated in terms of average packet delay, grant utilization, number of wavelengths used, and resequencing delay in comparison to modified-IPACT, the recently proposed First-Fit DBA (FF-DBA), and water-filling-algorithm-based DBA (WF-DBA) algorithms. Simulation results confirmed the validity of the proposed DBA algorithm.