乙太被動光纖網路中利用PRNN預估器作品質服務提升之動態頻寬配置研究

Abstract

乙太被動光纖網路（EPON）因其成本低廉之乙太網路設備及簡單、易維護之被動光纖架構，被認為是最佳之接取網路解決方案。隨著寬頻的普及與傳輸速率的提升，由語音、視訊與數據等結合的三合一服務（Triple Play）成為新趨勢，而乙太被動光纖網路整合既有基礎光纖網路與成熟之乙太網路技術，使得它成為提供三合一服務的極佳選擇。而為了提供服務使用者更快速以及更穩定的傳輸品質，有效地配置頻寬以保證服務品質（Quality of Service）便成為它的一個重要之研究課題。 在本篇論文中，我們提出了一個於乙太被動光纖網路中利用PRNN預估器作品質服務提升之動態頻寬配置方法。我們利用PRNN預估器收斂快速及預估準確之特性，針對及時性服務（例如語音服務、視訊服務）及非及時性服務（例如網際網路資料傳輸）於局端設備（OLT）作未及時回報之資料流量預測，而利用此預估結果作為頻寬分配之依據。模擬的結果顯示，我們所提出的利用PRNN預估器輔助作動態頻寬分配之方法確實能夠讓語音及視訊服務封包的平均延遲較Q-DBA方法分別改善26%及29%，對於資料封包而言，其平均延遲改善約34%，而系統效能則改善約2%。

The Ethernet passive optical network (EPON), which represents the combinations of low-cost Ethernet equipment and simple fiber infrastructure, is considered to be the best solution to the next generation access network. Owing to the pervasion of broadband and the requirement of high-speed transmission, triple play services (combines voice, video, and data services) have become the current trend. With the integration of existing fiber network and mature Ethernet technology, EPON is considered to be the best candidate to support the triple play services. In order to provide faster and more stable transmission, an adaptive dynamic bandwidth allocation for QoS (quality of service) guaranteed has become a crucial research topic. In this thesis, we propose a PRNN-based predictive QoS-promoted dynamic bandwidth allocation for EPONs. With the characteristics of fast convergence and accurate prediction, the PRNN-based predictor is selected to predict the late-reported traffic (real-time and non-real-time traffic) and the result of prediction is a basis for the dynamic bandwidth allocation at OLT. Simulation results show that the proposed predictive Q-DBA method improves the average voice and video delay time by an amount of 26% and 29% than Q-DBA method, respectively. The predictive Q-DBA method also improves the average data delay time about 34% and the system utilization by an amount of 2%.