Load Balance and Seamless Roaming with QoS support in IEEE 802.11 WLAN

本論文研究探討了在IEEE 802.11無線區域網路下支援服務品質的負載控制方法。我們所提出的ELB方法用動態的調整AP之間的網路負載分佈以達到負載平衡的目標。我們根據每個客戶端的統計特性進行負載平衡，並以允入控制來避免流量雍塞的情況發生。透過將使用者區分為三個等級，並控制每個使用者的使用頻寬來達到維持服務品質的目的。而進行漫遊的使用者，在我們的機制下，經由在新的AP上的頻寬預先保留，也可以維持一定的服務品質。除此之外，我們的ELB不需要修改任何的硬體機制，就可以運作在現存的802.11b無線區域網路中。最後，我們也對我們的機制做了模擬與實作，並量測、比較了我們的機制的表現。結果指出我們的結果可以有效的平衡AP間的負載，讓頻寬達到更大的使用效率，也能維持令人滿意的服務品質。This thesis presents and evaluates a mechanism for the load control with QoS supported in IEEE 802.11b Wireless LANs. Our mechanism named Enhanced Load Balance (ELB) dynamically adapts load distribution over APs to achieve load balance. The ELB mechanism balances the load by STAs’ statistical traffic load. This mechanism also performs admission control to avoid congestion. The ELB mechanism maintains QoS by classifying STAs into three classes and control the traffic flow of every STA. The roaming STAs can get enough bandwidth to maintain the QoS in the new AP by the bandwidth reservation mechanism of ELB. ELB can be used on top of the standard 802.11b access mechanism without requiring any modification or additional hardware. The performance of the IEEE 802.11 protocol with or without the ELB mechanism is investigated in the paper via simulation and implementation. The results indicate that our mechanism can balance the load effectively and the bandwidth can be fully utilized. Therefore, QoS can also be maintained