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Title: RED佇列管理機制對VoIP服務品質之影響分析
Study of VoIP Service Quality in Control of RED Management
Authors: 莊景舜
Chuang, Chin-Shun
Contributors: Horng, Mong-Fong
Keywords: 佇列管理;類神經網路
Queue Management;VoIP;Neural Network
Date: 2006
Issue Date: 2011-05-24 15:12:07 (UTC+8)
Publisher: 高雄市:[樹德科技大學資訊工程學系]
Abstract: VoIP已經成為現今網際網路最重要的服務之ㄧ,因此VoIP的品質保障技術也變的十分重要。本文的重點在探討ADSL路由器中,當使用RED佇列管理機制時,對於VoIP服務品質的影響。RED機制是藉由設定佇列的高、低臨界值以及丟棄率等參數,來決定何時、如何丟棄佇列內的封包,以避免過長以及過度變動的佇列所造成的等待延遲及延遲抖動。但是RED參數的決定,向來會因為網路品質的需求,例如延遲及延遲抖動的要求的不同而有所異,所以如何針對VoIP服務品質來決定路由器內RED佇列的操作參數,將是本文的研究重點之ㄧ。我們利用逆傳導類神經網路來學習決定RED機制參數的設定,在此網路模型,將以可容許延遲以及路由器頻寬為輸入,以RED機制參數為輸出,並藉由輸入出變數的關係推導取類神經網路的訓練樣本。模擬結果顯示,即使在低頻寬或非對稱式的傳輸環境下,本方法能夠有效地改善VoIP服務封包的延遲與抖動,藉由本文的成果可以提供網路或程式設計人員與ISP業者,在使用RED佇列管理機制時,於路由器設定的參考,建構出具有能適應VoIP訊務型態的佇列管理。
The quality issue of VoIP service is significantly attractive, since VoIP has become a promising service on Internet. In this thesis, the effectiveness and performance of random early detection (RED) applied on ADSL routers to control VoIP service quality are investigated. In RED, the drop probability, maximum and minimum thresholds are three operational parameters to determine when and how to drop the packets in the queue of routers. The proper packet dropping will be helpful to reduce the queuing delay and jitter of VoIP packets caused by over-flow and high variation of packet queues. Additionally, the determination of operational parameters depends on the requirement of quality-of-service (QoS), for example differentiated delay and delay jitter. Thus how to determine the parameters is investigated in this thesis. A back-propagation neural network is proposed to learn the specifying the RED parameters. The inputs of this neural network are delay tolerance and available network bandwidth. and the output is the RED parameter. Simulation results demonstrate, even in low available bandwidth and asymmetrical bandwidth situations, the proposed approach effectively improve the delay and jitter of VoIP service packets. This work benefits network managers to enhance VoIP service by properly deploying RED queueing mechanism.
Appears in Collections:[資訊工程系(所) ] 博碩士論文

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