隨著無線通訊的日益普及，以及各類型網路加值服務龐大的資料量與即時傳輸已使得低頻率的無線通訊頻段過於擁擠而不敷使用，而Ka(26~40GHz)波段高頻寬特性正符合現今無線通訊的需要；地面多點分配系統(Local Multipoint Distribution System, LMDS)亦為使用Ka波段的通訊系統。 由於降雨衰減是造成使用此波段的LMDS性能低落的主因，故本論文乃考慮在典型的細胞規劃下，使用美商New Bridge LMDS系統規格，並且由實驗所得的雨衰資料而修改的Crane雨衰預測模型，來預估此系統在台灣地區其通道受降雨衰減影響下的特性。另外再藉由動態調變架構(Dynamic Modulation Scheme)應用在此系統中以求得最大的頻寬效益 There are more and more communication systems that operate at 28~40 GHz because of high data rate and broadband service, such as LMDS (Local Multipoint Distribution System). However, attenuation due to rainfall severely degrades the radio wave propagation at frequencies about 28GHz. The thesis, based on a typical LMDS architecture and LMDS specification of New Bridge System, uses modified Crane model by our measurements to predict the channel characteristic in terms of cumulative distribution function and further studies the channel utilization while the system by making use of the Dynamic Modulation Scheme technique to achieve the best bandwidth efficienc
