Analyzing the performance of centralized polling for long-reach passive optical networks

Long-Reach passive optical networks (LR-PONs) suffer from extremely long propagation delays that degrade the performance of centralized algorithms proposed for upstream bandwidth-allocation in traditional PONs. In this paper, we analyze the performance of two centralized dynamic bandwidth allocation algorithms; so called online interleaved polling and offline multi-thread polling, recently proposed in the literature for LR-PON. We investigate their performances in terms of packet pre-transmission delay. Simulation results show that although multi-thread polling succeeds in decreasing reporting and queuing delays, interleaved polling keeps a lower grant delay and therefore has better overall delay performance.