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標題: 802.11e無線網路之韋伯增強分散式通道存取
Weibull-Based Enhanced Distributed Channel Access in 802.11e Wireless LAN
作者: 吳哲彰
Wu, Che-Chang
關鍵字: IEEE 802.11e Wireless LAN
Quality of Service
Enhanced Distributed Channel Access
Weibull probability
出版社: 電機工程學系所
引用: [1] IEEE 802.11 WG, “International Standard for Information Technology —Local and Metropolitan Area Networks-Specific Requirements — Part 11:Wireless LAN MAC and PHY specifications," 1999. [2] IEEE 802.11 WG, “Draft Supplement to Standard for Telecommunications and Information Exchange between Systems-LAN/MAN Specific Requirements— Part 11: Wireless MAC and PHY Specifications: MAC Enhancements for QoS," IEEE 802.11e, 2004. [3] Lamia Romdhani, Qiang Ni, and Thierry Turletti, “AEDCF: Enhanced Service Differentiation for IEEE 802.11 Wireless Ad-Hoc Networks”, IEEE WCNC'03 (Wireless Communications and Networking), vol.2, pp.1373-1378, 2003. [4] Q. Ni, L. Romdhani, and T. Turletti, “A survey of QoS Enhancements for IEEE 802.11 Wireless LAN”, Journal of Wireless Communications and Mobile Computing , vol.4, pp. 547-566, 2004. [5] Qiang Ni, Imad Aad, Chadi Barakat, and Thierry Turletti, “Modeling and Analysis of Slow CW Decrease for IEEE 802.11 WLAN”, IEEE 2003 International Symposium on Personal, Indoor and Mobile Radio Communication Proceedings , vol.2, pp.1717-1721, 2003. [6] Jong-Deok Kim and Chong-Kwon Kim, “Performance analysis and evaluation of IEEE 802.11e EDCF”, Wireless Communications and Mobile Computing, vol4, pp.55-74, 2004. [7] “The ns Manual”, [8] “Network Simulator (ns), version 2”, [9] “An IEEE 802.11e EDCA and CFB Simulation Model for ns-2”, [10] Giuseppe Bianchi, “Performance Analysis of the IEEE 802.11 Distributed Coordination Function”, IEEE Journal on Selected Areas in Communications, vol.18, pp.535-547, 2000. [11] Kanghee Kim, Aftab Ahmad, and Kiseon Kim, “A Wireless Multimedia LAN Architecture Using DCF With Shortened Contention Window for QoS Provisioning”, IEEE Communications Letters, vol.7, pp.97-99, 2003. [12] Larry L. Peterson and Bruce S. Davie, “Computer Networks”, Morgan Kaufmann Publishers, 3nd Ed, 2003.
摘要: 隨著無線網路的發展,帶給我們很多的便利。為了在無線網路802.11上提供服務品質保證,因此802.11工作小組制訂了一個可以支援服務品質的新標準,名為802.11e,其中包含了一個以競爭視窗為基底增強分散式通道存取機制(EDCA)。在EDCA中,當工作站數目增多時,傳送封包的碰撞率增加,而且每個佇列在進入競爭週期時,產生的後退時間造成時間槽空閒之浪費。因此有學者提出適應性增強分散式協調機制(AEDCF),其目的是在工作站數目增加時,降低碰撞率。 在本論文中,我們提出一個新的方法,隨著網路狀態改變,我們利用韋伯機率分佈來找出相對應之網路狀態的最佳競爭視窗值,而且參數能隨著工作站數目以及平均碰撞率做動態調整。 最後,我們使用NS2模擬分析所提出的韋伯增強分散式通道存取(WEDCA),和增強分散式協調機制(EDCA)、適應性增強分散式協調機制(AEDCF)的效能差異比較。我們發現WEDCA能強化網路的公平性,所以公平性的表現比AEDCF好,而且使用動態參數的WEDCA,比使用固定參數的WEDCA和其他機制更能隨著網路狀態做適應的調整,而得到比較好的效能。
The development of 802.11 wireless local area networks makes our life more convenient. In order to provide Quality of Service (Qos), IEEE 802.11 working group has defined a new standard called IEEE 802.11e. It includes a contention-window based access control algorithm called enhanced distributed channel access (EDCA). In EDCA, the collision rate increases when the number of stations increases. In addition, backoff time results in the waste of the available transmission time. To reduce collision rate as the number of stations increases, adaptive EDCF (AEDCF) was proposed. In the thesis, we proposed a new solution called Weibull-based EDCA. In our algorithm, we use Weibull distribution probability to find the best contention window value corresponding to the current network state. The parameters in the distribution can be dynamically adjusted according to the number of stations and the average collision rate. Finally, we used Network Simulator Version 2 (NS2) to simulate our algorithms and compare them with EDCA and AEDCF. We found WEDCA provides better network fairness and adaptively adjust parameters of WEDCA was better than fixed parameters
其他識別: U0005-0208200712411300
Appears in Collections:電機工程學系所



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