在這日新月異的影音多媒體時代裡，隨著高速行動使用者的增加，以及強烈之低延遲、高速行動傳輸、品質保證(QoS)之需求，讓風靡一時的802.11 無線區域網路也難以招架，更不用奢望能有傳輸範圍可達數公里之無線網路。有鑑於此，WiMAX Forum 歷經多年的研究，修正了8021.6-2004 (Fixed WiMAX)，終於在2005 年12月提出了Mobile MiMAX (802.16e)，也因802.16e 誕生解決了802.11無法提供低延遲、高速行動傳輸及服務品質(QoS)保證之問題。

802.16e 都會型無線寬頻網路雖然擁有低延遲、高速行動傳輸及品質保證(QoS) 之功能，但長期跟隨在802.11 無線區域網路中之頻寬資源不足問題，對802.16e 都會型無線寬頻網路而言依舊是無法克服之嚴重問題，所以為了節省及有效利用頻寬，「頻寬管理」亦將成為802.16e 都會型無線寬頻網路的一大挑戰。

有鑑於此，故在本篇論文中，我們將整合適應性調變與編碼機制」Adaptive Modulation and Coding (AMC)、
「適應性允許進入控制機制」Adaptive Call Admission Control (ACAC)，及在滿足所有連線之QoS 條件下，提出「適應性動態資源調整機制」Adaptive Dynamic Subcarriers Allocation Scheme
(ADSAS)，並針對802.16e 影音多媒體下載方面做最佳化之頻寬分配管理，甚至可在頻寬資源不足或頻寬資源已分配完之情況下，依每一個SS 之buffer 暫存量、video 播放速率、傳輸模式及QoS 需求等級，規劃出擷取優先順序及擷取數量表，進而擷取已上線之使用者的頻寬，並重新調整分配，讓有限的頻寬被充分利用，達到增加連線數之功能。

To download the multimedia fast in anytime and anywhere, almost mobile subscribers aspire to have a wireless network with low latency, high speed mobile transmission, and guarantee of QoS, but it seems very difficult to find out until the mobile WiMAX. The mobile WiMAX (802.16e) provides the functions of low latency, high speed mobile transmission, and guarantee of QoS, but the shortage of bandwidth is an existing problem to wireless network, it can’t be resolved for us, due to government rules. So we just can do one thing that is saving the bandwidth, don’t waste it, that’s all. How to saving the bandwidth, right here we purpose a novel scheme of Adaptive Dynamic Subcarriers allocation (ADSAS). It can not only saving the
bandwidth, also can increase the connection capacity of Base Station during the shortage of bandwidth situation. The ADSAS mainly integrates the “Adaptive Modulation and Coding Scheme, AMC＂ with the “Adaptive Call Admission Control Scheme, ACAC＂. And it is also consider the QoS of all connected subscribers. So it is a nice scheme for bandwidth management.How to increase the connection capacity for mobile WiMAX (802.16e), first the ADSAS will require all connected subscribers to respond the buffer sizes and the transmission mode,then according to them, we can make sure how long the base station doesn’t need to provide the bandwidth for the connected subscriber.
Meanwhile release the bandwidth of the connected subscriber to new subscriber. So that is ADSAS rule.

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