Optimization of Channel Utilization with Delay Guarantee for IEEE802.11n WLAN

[[abstract]]本篇論文針對IEEE 802.11 無線網路的媒體存取控制層提出了一個完整的設計。首先，我們提出一個雙向傳輸法去改善在無線網路中上傳及下載的非對秤性問題。第二，我們提出一種數學分析近似法去計算在飽和狀態下IEEE 802.11無線網路的訊框延遲分佈，我們經由模擬去證明我們的方法可以有效並且快速的計算出訊框的延遲分佈。第三，我們去分析通道使用率與競爭窗之間的關係，我們發現假設我們給定品質保證的需求及使用者的個數，如果我們要最佳化通道使用率，我們必須去調整起始的競爭窗。最後，我們使用訊框延遲分佈的數學模型、最佳的起始競爭窗、雙向傳輸法去設計出允入控制演算法，這方法可以提供品質保證並且有效的改善系統效能。[[abstract]]This thesis proposes a completed design for the IEEE802.11 contention-based WLAN Medium Access Control (MAC). Firstly, we present a bidirectional transmission method to solve the asymmetric problem between upstream and downstream. Secondly, we present an analytic method to approximate the distribution of frame delay in IEEE 802.11 DCF WLAN under the saturation condition. We demonstrate that our method can efficiently calculate the delay distribution and is fast. Thirdly, we analyze the relation between channel utilization and the minimum contention window size. We find that the maximum channel utilization can be achieved only by tuning the minimum contention window size if the quality of service (QoS) requirement and the number of stations are given. Finally, we use the delay model, optimal minimum contention window size and bidirectional transmission method to design an admission control algorithm that can provide QoS and improve system efficiency.[[note]]碩