全球互通微波存取(WiMAX)是第四代的無線寬頻網路標準，它具有低成本、高速率與較大的傳輸距離，且可提供多種不同類型的服務品質(Quality of Serve, QoS) 。 因此在不同應用上，要使這些不同QoS的封包能夠有效使用網路資源就非常重要。為了分配有限的頻寬，使得即時性資料的流量與延遲時間得以確保，並且避免非即時性資料出現等不到分配的機會(starvation of bandwidth)，WiMAX網路需要一個很有效率的排程法。然而，在IEEE 802.16標準中並沒有提供上下載頻寬分配的排程法，這部分將留給通訊設備商和學者自行設計，因此這方面，有非常多的探討與研究。
　　本論文中將會提出適應於不同比例資料流負載下，可保證各等級連線能獲得最低額定頻寬的一種演算法，因從考慮佇列長度頻寬分配法中(BAQL)發現，在不同負載比例下，需要根據負載比例來更動加權值，才可達到保證頻寬，所以我們為了要解決此一缺點，提出保證最低比率頻寬演算法。一開始根據考慮佇列長度頻寬分配法推算出各個佇列所分配到的頻寬，再根據各個佇列被保證的最低比率，使用保證最低比率頻寬演算法來調整各個佇列所分配到的頻寬，來達到我們所設定的額定頻寬。最後把模擬結果與考慮佇列長度的頻寬分配法做一比較，在不超越BAQL限制下，所得到的性能評估確實能保證最低比率頻寬。

Worldwide Interoperability for Microwave Access (WiMAX) is a 4G broadband wireless access (BWA) technology. It provides low cost deployment, high data rate and large coverage. WiMAX supports Quality of Service (QoS) for five types of applications. Thus, it is very important to allocate network resource to different classes of traffic efficiently so that the delay of real-time service can be guaranteed and the starvation of bandwidth for non-real-time service can also be avoided. Nevertheless, the IEEE 802.16 standard does not define radio resource management and scheduling algorithm. This is left for designers and researchers to explore.

　　In this study, we propose an algorithm in which each connection can get a minimum ratio of bandwidth for all kind of traffic loads. In bandwidth allocation according to queue length (BAQL), weight is decided by the queue length and allocated bandwidth is proportional to the load. Therefore, the QoS requirement of real-time traffic cannot be satisfied. Although the real-time traffic can be assigned more bandwidth by multiplying a constant αwith its queue length, it is very difficult to design this constant for a required QoS. Therefore, we propose an algorithm in this paper to assure the minimum ratio of bandwidth for real-time traffic. We simulate it with BAQL and the result is the same as predicted. The QoS requirement of real-time traffic can be satisfied with this algorithm.

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