為了達到比例式延遲差異性，一個著名的等待時間優先權排程因應而生。在中央集權式雙向網路，像是光纖同軸混合網路、無線非同步傳輸模式網路以及無線架構網路中，這個排程可在下行傳輸中，達到很好的比例式延遲差異性；然而其卻不適用於上行傳輸，這是因為中央控制器不容易得知上傳封包之等待時間。

　　在這篇論文中，我們提出一個框架式頻寬分配的方法，使得上行傳輸也能達到比例式延遲差異性。當全部的頻寬需求大於給上傳通道的頻寬時，我們利用四種頻寬配置演算法: (1) 比例式線性分配演算法；(2) 比例式多項式分配演算法；(3) 比例式最大最小分配演算法；(4) 比例式最小最大分配演算法，來達到比例式延遲。

　　而當全部頻寬需求小於通道的頻寬時，如果配置給使用者的頻寬剛好等於他們所預估需要的，那麼可能會有一些頻寬的浪費，為了避免此種的浪費，在此情況下，我們也提出了四種頻寬配置演算法: (1) 公平性分配演算法；(2) 加權式分配演算法；(3) 滿足需求參考先前分配演算法；(4) 滿足需求預測未來分配演算法。

　　實驗結果顯示，比例式最小最大分配演算法的方法可以達到非常好的比例式延遲，效果也比其他方法來得顯著。因此，在上行通道中，能提供比例式延遲差異性，比例式最小最大分配演算法是最好的選擇。

　　從避免頻寬浪費的觀點，實驗的結果顯示，公平性分配演算法、滿足需求參考先前分配演算法與滿足需求預測未來分配演算法，這三個方法可以達到很好的節省頻寬效果。除此之外，實驗的結果也顯示避免浪費頻寬的方法會影響延遲的比例。

　　To achieve the proportional delay differentiation, a famous method, waiting time priority (WTP) scheduler, was proposed [1]. In a central-controlled bi-directional network, like Hybrid Fiber-Coax Networks (HFC)[2,3], Wireless ATM (WATM)[4, 5, 6, 7, 8 ], and wireless infrastructure [9, 10, 11], this scheduler does achieve the proportional delay differentiation very well in downlink transmission. However, it is not suitable in uplink transmission because the central controller perceiving the waiting time of upstream packets is difficult. In this thesis, we proposed a frame-based allocation mechanism to provide the proportional delay differentiation in the uplink transmission. Four bandwidth allocation algorithms, proportional linear algorithm, proportional polynomial algorithm, proportional max-min algorithm, and proportional min-max algorithm, were proposed to achieve proportional delay when the total predicted bandwidth requirement exceeds the bandwidth supplied by uplink channel. Besides, when the total bandwidth requirement is less than the link bandwidth, if the allocated bandwidth for a connection is equal to its predicted requirement, some bandwidth may be waste. In order to avoid this waste, we also proposed four bandwidth allocation algorithms, fair requirement allocation (FRA), weighted requirement allocation (WRA), requirement+previous allocation (RPA), and requirement+next allocation (RNA), in this case.

　　The simulation results show that the proportional min-mix algorithm can achieve the proportional delay very well and outperform other algorithms. Therefore, to provide the proportional delay differentiation in uplink transmission, the proportional min-max algorithm is the best choice.

　　The simulation results also show that FRA, RPA, and RNA can avoid the waste of link bandwidth. Beside, the method adopted in the non-congested state that the total bandwidth requirement is less than the link bandwidth actually affects the achieved delay proportion.

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