UHF頻道在棋盤式街道傳播之經驗統計模式

Abstract

在本論文中，吾人利用三維射線追蹤傳播模式﹐並建立街道兩旁的有效 反射面統計模式以統計的方法來建立電波在棋盤式街道環境中傳播的平均 場強經驗模式 與衰落模型這兩者可合併計算電波的隨機場強。利用射線 追蹤法與映像法計算不同街道環境下的傳播損失並研究當發射站位置與接 收位置移動路徑不同時﹐平均場強經驗模式與衰落模型中各參數變化情形 。吾人發現在相似的街道環境下﹐接收天線沿不同路徑移動所得到之經驗 公式參數有相當的差異﹐在衰落模型研究方面﹐由於考量的是視線內傳播 其分仍以Rician fading為主﹐不過吾人發現。對於 Rician Factor在接 收天線沿平行街道路徑行進時其變化並無規則性﹐不過橫越街道的路徑則 其隨傳播距離增加而減小。 In our research, a 3-dimension ray-tracing technique is used to predict the receiving pwer on the street and establish the effective reflection surface for the walls beside the street. A statistical method is developed to establish average field strength empirical model and fading model for UHF radio propagate along a street in urban area , the random distribution of thereceiving power can be computed by these two model. we can predict the path loss along differentstreet by ray-tracing technique and image method,the difference of the parameters for these two model is investigated when the transmitter and the movingpath of receiving are changed. It is found that there is quite different when the moving path of receiver is changed for the parameters of empirical formula on similar streets. It is considered to be line-of-sight propagation on thestreet, the small-scale fading envelopedistribution is Rician. It is found that no regular rule to describe the change of Rician factor when the moving path of reciever is along a street, but the Rician factor is descreated with the propagation path is increatedwhen the moving path of recirver is across a street.