IEEE 802.11無線區域網路(wireless LAN; WLAN)，是目前的無線區域網路技術中最廣泛使用的標準。目前隨著無線網路的發展，以及對即時性服務的需求，IEEE 802.11提出了IEEE 802.11e媒介存取控制層(medium access control; MAC)協定來保證服務品質(quality of service; QoS)。主要影響優先順序的競爭參數為：仲裁訊框間間隔(arbitration inter-frame space; AIFS)，競爭視窗最小值(contention window minimum ; CWmin) 。目前有許多針對調整服務品質競爭參數的研究，以達到差異性服務的目的。但是大多沒有明確指出競爭參數之間的關聯性和如何針對各種不同情況調整競爭參數。
　　本論文中，我們以傳統分散式協調功能(distributed coordination function; DCF)及加強分散式協調功能(enhanced distributed coordination function; EDCF)為基礎，分別變動仲裁訊框間間隔和競爭視窗最小值，觀察在不同站台(station)數量下，系統產能(throughput)以及延遲時間(delay time)的變化。藉由分析模擬結果，我們提出兩者間相對的關聯性，以及對於不同情況的要求，該如何調整競爭參數的建議。

The IEEE 802.11wireless LAN (WLAN) is the most widely used standard nowadays for wireless LAN technology. With the development of wireless network and the requirement of real-time service, IEEE 802.11 proposed IEEE802.11e medium access control (MAC) protocol to guarantee quality of service (QoS). The major effect order of priority competition parameter is arbitration inter-frame space (AIFS) and contention window minimum (CWmin). At present there are many research aims at the adjustment competition parameter of quality of service to achieve the different service the goal. But most of them does not explicitly pointed out the correlation between competition parameters and how to adjust competition parameters with each kind of different conditioning.
In this paper, we change individually the arbitration inter-frame space and contention window minimum based on the distributed coordination function (DCF) enhanced distributed coordination function (EDCF) to observe the variation of system throughput and delay time under different number of stations. We present the comparative relationship between both of parameters, and have suggestions of how to adjust competition parameters with each kind requirement of different conditioning by analyzing the result of simulations.

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