目前的行動通訊網路朝超微細胞（Pico-Cell）架構（縮小細胞服務範圍）發展，以利通道重新使用，提高系統服務效能。
但縮小細胞範圍會增加移交(Handoff) 發生機率，一般的使用者最不希望正在通訊的連線被中斷，所以降低移交斷訊率(Handoff dropping ratio)極為重要。一般頻寬保留機制雖能降低移交斷訊率，但卻會犧牲新連線(New call)的使用頻寬，造成新連線阻塞率（New call blocking ratio）過度的上升; 或是沒能真正配合網路流量變化做最佳化頻寬配置及流量管理，使得系統頻寬使用率(System bandwidth utilization)下降。

在本論文中，我們提出一個動態頻寬保留（dynamic bandwidth reservation；DBR）機制，針對在不同環境下，移交連線數目和新連線數目的比例是不一樣的，而我們所提出的DBR演算法，會隨著環境的不同，而動態的調整移交連線和新連線保留的頻寬，使得新連線阻塞率不會過度上升，所以我們所提出的演算法，不論在什麼環境下，都能使移交斷訊率和新連線阻塞率維持在可接受的範圍之內，並提昇系統頻寬使用率。

The current cellular network was proceeded toward the “ Pico-Cell” architecture (decreasing cell ranges) to facilitate channel reuse and improve the system performance. However, decrease of cell range will increase the chance of handoff. Although most of the general bandwidth reservation schemes could lower the handoff dropping ratio, but they would also sacrifice the bandwidth of new call, which causes the over-raising of new call blocking ratio. On the other hand, they might also fail to adjust the optimization of bandwidth allocation and traffic management according to the network traffic variation.

In this paper, we propose a dynamic bandwidth reservation (DBR) system. There are always differences between the handoff call number and new call number in different environment, and our DBR algorithm could dynamically adapt the reserved bandwidth between the handoff call and new call, which prevents the over-raising of blocking ratio of new call. Therefore, our algorithm could keep handoff dropping ratio and new call blocking ratio in the tolerant range and improve the system bandwidth utilization despite the change of environment.

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