| Summary: | 碩士 === 國立成功大學 === 資訊工程學系 === 102 === In recent years, passive optical networks (PONs) have been widely chosen for deploying optical access networks. With the widespread deployment of PONs, research focus has shifted to their scalability, with longer reach and higher split ratio. By exploiting both optical amplifiers, long-reach PONs (LR-PONs) extend the coverage of a PON from short-reach 20 km to 100 km and beyond. By reducing the number of network elements, the network’s Capital Expenditure (Capex) and Operational Expenditure (Opex) can be reduced.
On the other hand, due to the increased distance between optical network terminal (OLT) and optical network unit (ONU), the propagation delay increases to 1ms. When an ONU requests upstream bandwidth, it will take a longer time to receive the acknowledgement from the OLT before it can transmit its upstream packets. Thus, the traditional dynamic bandwidth allocation (DBA) in LR-PONs must be redesigned and under review.
In this thesis, we propose a multi-thread fitting scheduling timing-elastic weighted granting (MT-FST-EWG) dynamic bandwidth allocation algorithm (MT-FST-EWG) which is to merge the advantages of both fitting scheduling timing-elastic weighted granting (FST-EWG) and multi-thread polling (MTP) and improve the effectiveness of FST-EWG shortage in LR-PON. We evaluate the throughput-delay performance of MT-FST-EWG, FST-EWG and MTP. We find that MT-FST-EWG gives lower delays and idle times than FST-EWG and MTP. At the same time, the propagation delay problem FST-EWG faced was solved by MT-FST-EWG.
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