IEEE 802.11e EDCA之效能研究

The Study of the Performance in IEEE 802.11e EDCA

莊富元(Fu-Yuan Chuang)

指導教授 ： 吳和庭

國立臺北科技大學/電資學院/資訊工程系研究所/碩士(2008年)

https://doi.org/10.6841/NTUT.2008.00410

摘要

近幾年來，隨著無線寬頻時代的來臨，使用者對於無線網路的需求更為多樣，因此在無線網路上多媒體的應用也有更多元與大幅度的成長。因此，如何在無線區域網路中提供服務品質(QoS)，是個相當值得研究的議題。所以，IEEE 802.11 Task Group E為此而提出了IEEE 802.11e使得在無線區域網路中提供具服務品質(QoS)傳輸的能力。其中一個存取機制是藉由擴充原本802.11中DCF的存取機制，稱為enhanced distributed channel access(EDCA)，它定義了四個Access categories (AC)藉此用來實現具有優先權的QoS。

本論文在802.11e中EDCA存取模式的環境下提出一個可以增進效能的方法，QAP藉由模糊控制系統動態調整EDCA Parameter Set 中Contention Window的參數值，使得QSTA中的各個AC可以獲得更適合目前網路狀況的Contention Window初始值，進而提升整體網路的throughput，降低網路系統碰撞的機率和封包傳送的延遲時間。

關鍵字

802.11e ； 服務品質 ； 競爭窗口 ； 無線區域網路 ； Fuzzy

並列摘要

In recent years, IEEE 802.11 wireless LAN has been widely deployed. With the ever increase of transmission bandwidth, there is a growing demand on multimedia applications for such a wireless network. Therefore, much interest has been devoted to the design of wireless local area networks with quality of service. IEEE 802.11 Task Group E has proposed a new standard, IEEE 802.11e, recently to provide QoS capability for multimedia traffic in the IEEE 802.11 wireless network.

In this thesis, we propose a mechanism to improve the performance of enhanced distributed channel access mechanism of IEEE 802.11e. The QAP dynamically adjust the maximum and minimum contention window size for each AC of EDCA Parameter Set, by using the Fuzzy control method to calculate the effects that each AC imposes on the network. Performance results via simulations have verified that the mechanism can decrease the collision probability and reduce the packet delay effectively.

並列關鍵字

802.11e ； Qos ； Contention Window ； Fuzzy

參考文獻

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