臺灣博碩士論文加值系統

隨著無線網路的發展，增強了網際網路的使用性，另一方面，由於多媒體資料的盛行，所以服務品質(QoS)的需求也越顯現其重要性。而傳統的IEEE 802.11無法保證即時性資料的服務品質，而IEEE802.11e就是為了支援服務品質而被制定的規範。但是IEEE 802.11e HCCA所提供計算TXOP( Transmission Opportunity)的方式，只適用於傳送CBR類型的資料，並不適用於傳送VBR類型的資料。
本篇論文提出一個以高斯近似法去的方式，來估測所有工作站中所產生的VBR類型的總資料量，然後估算出CAP的大小，並依比例來做為允入控制的條件。在每個SI中，我們將會依據目前每個flow封包遺失的狀況來調整輪詢之次序，使得每個flow之個別遺失率都可以維持在預設的標準。

The widely development of the WLAN technology makes the access of network more convenient. As new applications are created, quality of service (QoS) demand from users is getting important. The traditional IEEE 802.11 standard can not support QoS for real-time data and a new standard, IEEE 802.11e, is designed to solve the QoS issue. However, the call admission control (CAC) algorithm and the calculation of TXOP in IEEE 802.11e are only suitable for transmission CBR traffic. For VBR traffic, the loss rate will be high.
The thesis first proposes CAC algorithm based on Gaussian approximation of total arrival traffic. Then a dynamic TXOP allocation algorithm is proposed to efficiently utilize the bandwidth. We will adjust the polling order according to current loss rate for every flow such that each flow has the same loss rate.

中文摘要
英文摘要
目 錄 I
表 目 錄 III
圖 目 錄 IV
第一章 序論 1
1.1 前言 1
1.2 研究動機與目的 2
1.3 論文架構 3
第二章 背景與相關研究 4
2.1 IEEE 802.11 MAC 簡介 4
2.1.1 分散式協調功能(DCF) 5
2.1.2 集中式協調功能(PCF) 6
2.1.2.1 免競爭周期之介紹 7
2.1.2.2 PCF傳輸程序 8
2.2 IEEE 802.11e MAC簡介 9
2.2.1以競爭為基礎的媒介存取機制(EDCA) 10
2.2.2以輪詢為基礎的媒介存取機制(HCCA) 11
2.2.2.1 Traffic Specification欄位介紹 13
2.2.2.2 IEEE 802.11e HCCA TXOP之求法 14
2.3文獻探討 16
第三章 以高斯近似法為依據的允入控制與動態頻寬分配機制之設計 18
3.1 方法說明 18
3.2系統說明與CAC演算法 19
3.3動態頻寬分配機制 21
3.3.1上傳輪詢機制 21
3.3.2下載傳送機制 26
第四章 模擬環境與數據分析 28
4.1模擬拓璞 28
4.2參數設定 29
4.3 模擬結果與數據分析 31
4.3.1不同的PHY Rate情況下建立連線個數之比較 31
4.3.2不同的PHY Rate情況下Loss Rate之比較 38
4.3.2.1 Direction : Downlink 38
4.3.2.2 Direction : Uplink 42
4.3.3不同的PHY Rate情況下Loss Rate與連線個數之比較 46
第五章 結論與未來研究方向 52
參考文獻 53

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