- 學位論文
IEEE 802.11e EDCA網路的頻寬分配方法
Bandwidth Assignment in IEEE 802.11e EDCA
摘要
IEEE 802.11無線區域網路，近年來已經是佈置無線區域網路的不二選擇，無線的特性彌補了有線網路需要佈建線路的缺點，被廣泛應用在許多場合，像是咖啡廳、速食店，許多國際大城更在全市佈建IEEE 802.11無線區域網路，是一個非常重要的產品。 IEEE(Institute of Electrical and Electronics Engineers, Inc)在2005年底正式通過了一項標準：IEEE 802.11e，IEEE 802.11e對於IEEE 802.11做了一些新增及修改。IEEE 802.11e提出了兩種通道存取機制：EDCA(Enhanced Distributed Channel Access)及HCCA(HCF Controlled Channel Access)。EDCA的實用性比較大，因為EDCA是一種競爭式通道存取機制，可以用來建置隨意網路(ad hoc network)，而HCCA是一種控制式通道存取機制，一定要有QAP(QoS Access Point)才可以建置網路，所以EDCA廣為設備商實做在產品中，HCCA則乏人問津。 IEEE 802.11e EDCA為了增強對QoS(Quality of Service)的支援，將訊框分成4種AC(Access Category)，並且允許每種AC使用不同的競爭參數以得到不同的傳輸品質，但是IEEE 802.11e EDCA並沒有提出調整競爭參數的方法，對於QoS的支援還有增強的空間，因此本論文提出一個新方法「倒數時間控制協定」(Backoff Time Controlled Protocol, BTCP)來調整這些競爭參數，加強IEEE 802.11e EDCA對QoS的支援。 模擬結果證實本論文提出的倒數時間控制協定能有效分配頻寬，改善訊框傳輸延遲，增強IEEE 802.11e EDCA對QoS的支援。
並列摘要
In recent years, IEEE 802.11 WLAN (Wireless Local Area Network) is the most selected technology to construct WLAN. IEEE 802.11 WLAN working with wired network in constructing seamless network is widely used by government, coffee shops, fast food markets…etc., it therefore became more and more important technology. In 2005, IEEE (Institute of Electrical and Electronics Engineers) ratified the standard IEEE 802.11e. It is an amendment of IEEE 802.11-1999. IEEE 802.11e proposes two channel access mechanism: EDCA and HCCA. EDCA is a distributed channel access mechanism, HCCA is a hybrid coordination function controlled channel access mechanism, equipment provider support EDCA in many equipment, otherwise, it is hard to find an equipment that support HCCA. IEEE 802.11e EDCA made some modify based on IEEE 802.11 DCF (Distributed Coordination Function), the main feature of modify is support QoS (Quality of Service). In IEEE 802.11e EDCA, frame is divided into four categories, different categories have different priorities to access channel by using different channel access parameters. This paper proposes a method to adjust these channel access parameters to enhance QoS support of IEEE 802.11e EDCA. Simulation result verifying the proposed method is effective in assign bandwidth, network manager can using the method to further control the QoS of four category of IEEE 802.11e EDCA.