WiMAX是一種新興的無線都會型網路通訊技術，它提供了高速度網路存取和多媒體的服務，而且可支援多種不同類型的QoS。因此在系統中，有效的分配頻寬給多種的服務類型是很重要的，所以當資料傳輸時，在頻寬有限的情況下，要確保即時性資料的流量和延遲時間，並有效地避免非即時資料發生飢餓現象，達到最有效的資源分配的目標，這方面的相關議題可加以探討。
目前有許多研究QoS排程分配中，但部分研究提出的分配演算法並沒有考量到佇列中個別的封包長度，而被分配到的頻寬可能使得最後一個封包只能送出部分，而讓封包延遲時間變大。本論文針對此方面問題，我們提出一種最後一輪頻寬調整機制，用於每次訊框根據不同服務類型配置頻寬之後，再檢查配置到的頻寬是否剛好等於佇列裡面的封包長度。如果上述條件不成立的話，即時性資料流可向非即時性資料流借貸頻寬，使得最後一個封包有機會完整被送出，降低封包平均延遲時間。

WiMAX is a new technology for wireless metropolitan area network (WMAN). It provides high speed internet access and multimedia service and supports a variety of types of Qos. Thus, it is important to allocate bandwidth to different class of traffic effectively in this network. The resource must be allocated effectively to guarantee the delay of real-time traffic and avoid the starvation of bandwidth for non-real-time traffic.
There are many studies for the scheduling of bandwidth in Wimax. However, the length of individual packet in the queue was not considered for most of them. Thus, only part of the last packet was scheduled after the allocating of bandwidth in these protocols. As a result, the last packet of each class may have to wait one more frame to finish its transmission. In this paper, we propose a protocol named “Bandwidth Adjustment Mechanism in the last Round (BA-LR)” to solve this problem. After the scheduling of those other protocols, the queue will be checked with BA-LR. If the last packet cannot be sent as a whole in this frame, the allocated bandwidth will be adjusted to send it in this frame or the next frame. If it is sent in this frame, the added bandwidth needs to be borrowed from a class of lower priority. Otherwise, the assigned bandwidth for the last packet may be returned to a class of lower priority in the next frame. Therefore, BA-LR will have two edition named BA-LR1 and BA-LR2. We will simulate these two protocols and study their performance in this paper.

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