Dynamic Bandwidth Allocation with Void Filling and Multi-thread for Long Reach WDM/TDM PONs

Dynamic Bandwidth Allocation is a major open research challenge in the migration of Passive Optical Network (PON) systems towards Long Reach PON, especially when hybrid WDM/TDM is used (LR WDM/TDM PON). New and efficient solutions for Dynamic Bandwidth and Wavelength Assignment are sought to address two main critical issues of such PON systems: how to schedule the transmissions over multiple wavelengths and how to efficiently exploit the bandwidth in presence of the long propagation delays that characterize long reach scenarios. While several DBAs have been proposed for long-reach single-wavelength PON system or for WDM/TDM hybrid PONs (with no regard to the long reach aspect), only few DBAs have been investigated in the case of combined LR WDM/TDM PON scenario. Regarding LR TDM PONs, one of the most performing and widely used dynamic allocation schemes is the Multi-thread polling. Although this algorithm has provided good results when applied in these kind of networks, it has never been implemented into a LR WDM/TDM PON. For what concerns this latter network configuration, one of the most promising candidate for upstream bandwidth and wavelength allocation is the Earliest Finish Time with Void Filling (EFT-VF) algorithm. In this work, for the first time, we implement the Multi-thread polling in a LR WDM/TDM PON providing results in terms of average packet delay. Moreover, we propose a new DBWA scheme based on an effective combination of some features of EFT-VF and Multi-thread algorithms, which leads to a performance improvement compared to these algorithms.