WiMAX發展至今已經制定出許多標準的規格，但在call admission control (CAC)、bandwidth request (BR)、bandwidth allocation和schedule的細節設計上並沒有標準的規劃和演算法。本文中，我們提出一個CAC機制叫作multi-modulation CAC。不同於目前大部分的CAC機制僅考慮到單一調變(modulation)的情況，我們的研究聚焦在多調變的環境上。並利用multi-modulation CAC改善傳統CAC無法在多調變底下正常運作的問題。我們提出的理論中，BS的CAC是藉由剩餘slot數決定是否要接受連線。最後，我們用網路模擬器NS-2 (network simulator version 2)作為測試實驗架構並分析評估實驗的系統效能。 / So far, WiMAX forum has worked out many specifications of the IEEE 802.16 standard. However, it does not have detailed mechanisms of connection admission control (CAC)、bandwidth request (BR)、bandwidth allocation and scheduling. In this thesis, we propose an admission control scheme called multi-modulation CAC. Rather than most CAC only considering the single modulation environment, our study focused on multi-modulation environment. We use the multi-modulation CAC to improve the traditional CAC can’t work well in multi-modulation environment. With the proposed scheme, base station performs connection admission control to decide whether or not to accept connection requests by number of the remained slot. Finally, we use NS-2 (network simulator version 2) as network simulator and develop an analytical model to evaluate the system performance.