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Author: 王澤霖
Che-lin Wang
Thesis Title: IEEE 802.11e EDCA中考量頻道狀態來動態調整等待時間的策略
A Dynamic Backoff Time Scheme with Considering Channel Condition for IEEE 802.11e EDCA
Advisor: 賴源正
Yuan-Cheng Lai
Committee: 楊傳凱
Chuan-Kai Yang
Bor-Shen Lin
Degree: 碩士
Department: 管理學院 - 資訊管理系
Department of Information Management
Thesis Publication Year: 2006
Graduation Academic Year: 94
Language: 英文
Pages: 30
Keywords (in Chinese): 增強分散式頻道存取法服務品質
Keywords (in other languages): EDCA, IEEE 802.11, QoS
Reference times: Clicks: 202Downloads: 1
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許多已提出的IEEE 802.11e的改良機制,對服務品質有越來越多的需求。它們大部分根據傳輸失敗的與否調整參數(例如CW),但都未考慮到在傳輸封包時的頻道狀態(頻寬)。在無線網路中,頻道狀態的變動是由於某些因素,像是移動性的站台、不同程度的干擾、位置相依錯誤。本篇提出擁有鏈結調適的增強分散式頻道存取演算法(EDCA-LA)來適應變動的頻道狀態。我們主張使較好頻道的站台設定較小的等待時間以達到較高的整體網路效能。模擬結果可以看出在產能和平均存取延遲方面,EDCA-LA都勝過標準的EDCA。

Abstract – Many enhanced schemes of IEEE 802.11e have been proposed to meet the increasing demand for Quality of Service (QoS). Most of them adjust the parameters, such as Contention Window (CW), according to whether the transmission is successful or failed, but don’t consider the channel condition (bandwidth) at transmitting packets. In a wireless network, the channel condition is time-varying due to some factors such as station mobility, time-varying interference, and location-dependent errors. In this paper, we propose the Enhanced Distributed Channel Access with Link Adaptation (EDCA-LA) algorithm by adapting with the time-varying channel condition. Our idea is to set the smaller backoff time for a station which has a better channel to achieve higher overall performance. Simulation results show that EDCA-LA outperforms the standard EDCA in terms of throughput and mean access delay.

摘要 I Abstract II 致謝 III Table of Contents IV List of Figures V List of Tables VI Chapter 1. Introduction 1 Chapter 2. Background 4 2.1. IEEE 802.11 MAC 4 2.2. IEEE 802.11e MAC 5 Chapter 3. EDCA-LA Algorithm 9 Chapter 4. Simulation 12 4.1. Simulation environment 12 4.2. Simulation results 14 Chapter 5. Conclusions 20 References 21

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