隨著科技的進步與發展，無線網路頻寬的需求也跟著日與俱增，IEEE 802.16也就是俗稱的WiMAX(worldwide interoperability for microware access)，它提供了一種新興的無線網路通信技術，主要應用於都會型網路，提供最後一哩(last mile)無線頻寬接入，做為纜線與DSL之外的另一項選擇。
本論文中主要探討實體層技術為正交多頻分工存取(orthogonal frequency division multi access；OFDMA)之網狀網路集中式排程，而由於網狀(mesh)架構並不像點對多點(point to multi-point；PMP)架構對於頻寬配置擁有實際的時槽配置資訊，因此每個用戶台(subscriber station；SS)必須透過一套共同的演算法來推算出自己傳輸資料的時間，故本論文選用四種鏈結選擇策略將其套入OFDMA二維配置演算法做一效能評估與比較。
由於IEEE 802.16網狀架構是一種多點跳躍(multi hop)的無線網路，故本研究加入允入控制機制(call admission control；CAC)，減少系統因為網路負載的提高造成大量封包壅塞於中繼用戶台的情形發生，並確保每個連線的資料都能順利傳送到目的端。
在本論文所評估的四種鏈結選擇策略：Nearest_to_BS_first、Farthest_to_BS_first、Lowest_load_first、Highest_load_first之中，從模擬結果可發現由於需求頻寬較大的鏈結在頻寬配置上是較不具彈性化，因此Nearest_to_BS_first 與Highest_load_first所呈現的傳輸效能較其他兩者佳。

With the advancement and development of technology, the bandwidth demand for wireless network is increasing greatly. IEEE 802.16 is commonly known as WiMAX (worldwide interoperability for microware access), which provides a new wireless communication method other than Cable or DSL to solve last-mile access issue in metropolitan area network (MAN).
Since IEEE 802.16 mesh network is one kind of multi-hop wireless networks, a call admission control (CAC) mechanism is used to minimize the situation that a large number of packets are jammed in the relay station while loading increases and to ensure packet delivery successfully.
This paper focuses on the centralized scheduling method for OFDMA(orthogonal frequency division multi access) mesh network. A base station (BS) does not broadcast MAP messages in mesh mode so each subscriber station (SS) must share a common algorithm to compute its own transmission time. Four different kinds of link selection schemes are compared in this paper using OFDMA two-dimensional frame structure.
In the four kinds of link selection schemes, Nearest_to_BS_first, Farthest_to_BS_first, Lowest_load_first, and Highest_load_first, we can find that the time-slot allocation of the highest load links is less flexible from the simulation results, and therefore the throughputs of Nearest_to_BS_first and Highest_load_first are better than the others.

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