適用於無線骨幹網路之考慮服務品質排程機制｜國立臺灣科技大學博碩士論文系統

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研究生：	廖立弘 Li-hung Liao
論文名稱：	適用於無線骨幹網路之考慮服務品質排程機制 QoS-aware Scheduling (QAS) Mechanism for Multihop Wireless Backhaul Networks
指導教授：	鄭瑞光 Ray-guang Cheng
口試委員:	陳金蓮 Jean-lien Chen 曹孝櫟 Shiao-li Tsao 楊人順 Jen-shun Yang
學位類別：	碩士 Master
系所名稱：	電資學院 - 電子工程系 Department of Electronic and Computer Engineering
論文出版年：	2006
畢業學年度：	94
語文別：	中文
論文頁數：	47
中文關鍵詞：	位置相關、漣波協定、考慮服務品質排程、無線骨幹網路、鏈狀拓撲、公平性
外文關鍵詞：	Wireless backhaul network, chain topology, Qos-aware scheduling (QAS), Ripple protocol, location-dependent, fairness
相關次數：	點閱：509 下載：3
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近年在戶外環境的相關應用中，業者已逐漸以無線骨幹網路來取代目前常見的有線骨幹網路。無線骨幹網路主要佈建於街道上，用戶可透過以無線鏈結相連的數個無線區域網路接取點(AP)，將資料以多躍式傳輸的方式逐步轉送到與有線網路相連的閘道器，藉以降低網路的佈線成本。然而無線傳輸的廣播特性以及無線區域網路的競爭式通道存取模式，也讓多躍式無線骨幹網路面臨“網路整體有效傳輸率下降”以及“接取點流量與所處位置相關”等重大問題。為了解決這些問題，本研究室已經提出漣波協定來提升無線骨幹網路的有效傳輸率，而本論文則是基於漣波協定提出考慮服務品質之排程機制，進一步解決接取點流量與所處位置相關的問題，以滿足用戶的服務品質需求。
本論文首先針對單一訊務環境，提出了一個簡單的排程機制，讓系統內的每個封包均能依其抵達時間(而非其來到之位置)來決定傳送的優先順序，並針對這個排程機制提出一個佇列模型，以預估各接取點的產出率與封包的平均等待時間，再由系統模擬驗證分析的正確性。其次，再將此排程機制擴展到多重訊務環境，並分別結合嚴格優先權以及權重公平佇列等頻寬分配機制，以提供不同等級的服務。

‘Wireless backhaul network’ is a new option for providing public wireless access services in outdoor environment. In a wireless backhaul network, 802.11 WLAN APs are interconnected through wireless links and the communication between two APs is carried out through a number of intermediate APs via relaying packets from one AP to another. Due to the broadcast nature of the wireless channel and the contention-based medium access, the wireless backhaul network may suffer from the problems of low-utilization and location-dependent throughput. In order to enhance the utilization of the network, Ripple protocol was proposed. In this thesis, we will proposed a QoS-aware scheduling (QAS) mechanism, which is developed on top of Ripple, to resolve the location-dependent throughput problem and thus, meets users’ QoS requirements.
In this thesis, a simple first-come-first-serve (FCFS) scheduling mechanism is first proposed to support single traffic class such that the service order of each packet in each AP depends only on its arrival time rather than the location of the AP. An analytical method is then proposed to estimate the performance (i.e., the effective throughput of each AP and the mean system waiting time of each packet) of the QAS mechanism. The accuracy of the analysis has been verified by simulation. The scheduling mechanism is further extended to accommodate multiple traffic classes. Depending on the bandwidth allocation strategy adopted by the network operator, the proposed QAS mechanism can work with either a strict-priority scheduling algorithm or a weighted fair queueing algorithm to meets users’ QoS requirements.

中文摘要.................................................I
英文摘要................................................II
誌謝...................................................III
目錄....................................................IV
圖表索引................................................VI
第一章  簡介.............................................1
  1.1  研究背景..........................................1
  1.2  研究問題..........................................4
  1.3  研究動機..........................................6
  1.4  漣波協定背景介紹研究動機..........................8
第二章  系統模型........................................11
  2.1  系統環...........................................11
  2.2  基本假設.........................................11
  2.3  問題與目標.......................................13
第三章  考慮服務品質之排程機制..........................14
  3.1  考慮服務品質之排程機制的設計概念.................14
    3.1.1  機制概念描述.................................14
    3.1.2  機制運作流程.................................15
    3.1.3  初始化機制...................................17
  3.2  理論分析.........................................17
    3.2.1  基礎佇列理論(Queueing Theory)................17
    3.2.2  單類別優先權(single priority)之近似佇列模型分析...21
  3.3  多類別優先權(multiple priorities)之近似佇列模型分析...26
  3.4  免排序之佇列結構概念.............................28
第四章  系統模擬與分析..................................30
  4.1  分析驗證.........................................31
    4.1.1  單類別優先權之分析驗證.......................31
    4.1.2  多類別優先權之分析驗證.......................33
  4.2  漣波協定結合考慮服務品質之排程機制的前後比較.....35
    4.2.1  觀察考慮服務品質之排程機制的效用.............35
    4.2.2  觀察考慮服務品質之排程機制的公平性...........36
  4.3  探討結合兩類優先權排程機制的影響.................38
    4.3.1  結合嚴格優先權的影響.........................38
    4.3.2  結合權重公平佇列的影響.......................40
第五章  結論............................................44
參考文獻................................................45
作者簡介................................................47

                                

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