乙太被動式光纖網路中考慮延遲之動態頻寬分配技術

Delay Sensitive EPON Dynamic Bandwidth Allocation Mechanism

曾士瑋(Shih-wei Tseng)

指導教授 ： 嚴威

大同大學/電機資訊學院/資訊工程學系所/碩士(2006年)

摘要

近年來，被動式光纖網路逐漸成為次世代存取網路的解決方案之一。對於電信業者來說，經濟的設備以及維護費用是被動式光纖網路最吸引他們的地方，被動式光纖網路具有樹狀的拓樸，並且從光網路終端機(Optical Network Unit)到光路終端機(Optical Line Network)之間的頻寬都是共享的。因此，很多論文設計了多種動態頻寬分配技術來公平且有效地管理頻寬。
在此篇論文中，我們將介紹並檢討多種已提出的動態頻寬技術，並列出它們的優點及弱點。此篇論文的目標之一就是對於被動式光纖網路目前的發展做一個整體的介紹與研究。此外，在論文中也會介紹我們所提供的新方法，此方法同時考慮了頻寬的共享以及輪詢所產生的延遲。
在被動式光纖網路系統中，大部分的動態頻寬分配演算法只針對於頻寬的分配做研究，並沒有考慮到光網路終端機之間輪詢時所造成的延遲。此延遲對於許多即時的視訊及音訊的應用程式會造成極大的影響，尤其是在網路流量高負載時。因此，在設計動態頻寬分配演算法的當中，光網路終端機之間輪詢所造成的延遲是不得不考慮的要素之一。所以我們所提出的方法不僅能夠公平的分配頻寬給各個光網路終端機，並且還降低了因為輪詢所造成的延遲。在被動式光纖網路領域裡面，此方法是第一個將延遲考慮進去的演算法。於結論當中，我們會對未來的研究方向以及要解決的問題作一個總結。

關鍵字

乙太被動式光纖網路、動態頻寬分配演算法

並列摘要

Ethernet passive optical network (EPON) is one of the potential solutions for the next generation access technology. Its economical equipment and maintenance costs are particularly attractive to telecommunication service providers. The EPON has a tree topology and the upstream bandwidth from optical network terminals to the optical line terminal is shared. To utilize the bandwidth in a fair and efficient manner, numerous dynamic bandwidth allocation schemes are proposed in the literature.
In this thesis, we will introduce and review these schemes, list their strength and weakness. One of our goals in this thesis is to give an overview to the current status of researches in this area. We will also introduce our work on a new scheme that considers performance on both bandwidth and delay.
In the EPON system, the existing algorithms of dynamic bandwidth allocation mainly focus on bandwidth allocation. The designers of these algorithms did not consider the delay resulted from the polling between ONUs. The delay will affect real-time video and audio applications. Thus, when we design a dynamic bandwidth allocation algorithm, the delay between the polling of ONUs is an important factor that we need to consider. We proposed a scheme that not only allocate the bandwidth fairly but also reduce the delay between the polling of ONUs. To our knowledge, this is the first attempt to consider both performance metrics in EPON. In conclusion, we summarize future works and point out the pending challenges for future study.

並列關鍵字

EPON、DBA、DELAY

參考文獻

[1] IEEE 802.3ah-2004, Ethernet in the First Mile.

[2] D. J. Xu, W. Yen, and E. Ho, “Proposal of a New Protection Mechanism for ATM PON Interface,” in Proc. of APOC 2001, Beijing, China, Nov. 2001.

[3] ITU-T Recommendation G.984.1, “Gigabit-capable Passive Optical Networks : General characteristics,” March 2003.

[4] G. Kramer and G. Pesavento, “Ethernet Passive Optical Network : Building a Next-Generation Optical Access Network,” IEEE Communications Magazine, Vol. 40, No. 2, pp. 66-73, Feb., 2002,.

[5] G. Kramer, B. Mukherjee, and G. Pesavento, “IPACT: A Dynamic Protocol for an Ethernet PON (EPON),” IEEE Communications Magazine, Vol. 40, No. 2, pp. 74-80, Feb. 2002.