IEEE 802.11e增強分散式通道存取之服務品質研究

THE QoS STUDY OF IEEE 802.11e ENHANCED DISTRIBUTED CHANNEL ACCESS

林大鈞(Ta-chun Lin)

指導教授 ： 陳建華

大同大學/電機資訊學院/通訊工程研究所/碩士(2005年)

摘要

IEEE 802.11e 媒體存取控制(MAC)是一個對IEEE 802.11無線區域網路(WLAN)標準的新興補充以支援服務品質(QoS). 802.11e媒體存取控制是以集中控制(centrally controlled)和競爭基礎(contention based)的通道存取機制為基礎.
本論文藉由NS-2模擬器來模擬競爭基礎的通道存取機制,稱做增強分散式通道存取(EDCA), 同時和既有的802.11媒體存取控制做比較.亦模擬了增強分散式通道存取的一項選擇性的功能,稱做免競爭爆發(CFB),可以允許多個媒體存取控制框架在單一個傳送機會(TXOP)中傳送.透過模擬研究可推斷出,增強分散式通道存取對於不同優先權的框架可以提供差異性的通道存取.並且免競爭爆發可以增加整個系統的吞吐量(throughput)來提昇增強分散式通道存取的效能.

關鍵字

服務品質

並列摘要

The IEEE 802.11e Medium Access Control (MAC) is an emerging supplement to the IEEE 802.11 Wireless Local Area Network (WLAN) standard to support Quality of Service (QoS). The 802.11e MAC is based on both centrally controlled and contention based channel access mechanisms.
In this thesis, we evaluate, via simulation in NS-2, the contention-based channel access mechanism, called Enhanced Distributed Channel Access (EDCA), and compare it with the 802.11 legacy MAC. We also evaluate an optional feature of the EDCA, called contention-free burst (CFB), which allows multiple MAC frame transmissions during a single transmission opportunity (TXOP). Through our simulation study, we conclude that EDCA can provide differentiated channel access to frames with different priorities. Moreover, the CFB is found to enhance EDCA performance by increasing the overall system throughput.

並列關鍵字

802.11e ； EDCA ； QoS

參考文獻

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[5] J. Prado, S. Shankar N, “Impact of Frame Size, Number of Stations and Mobility on the Throughput Performance of IEEE 802.11e,” IEEE WCNC, vol. 2, pp.789-795, March 2004.

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[1] IEEE Std. 802.11-1999, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications, Reference number ISO/IEC 8802-11:1999(E), IEEE Std. 802.11, 1999 edition, 1999.