建構室外巨細胞多重路徑到達時間及角度之新型模型

Abstract

摘 要 本論文主要是利用擴展後的Turin’s model 建構新式的無線電空-時通道脈衝響應模型，本模型延用Turin’s model 中以群集因子來描述多重路徑的群聚效應，並利用向量通道響應量測系統（RUSK Channel Sounder）獲取大型都會區、中小型都會區以及郊區不同頻寬的時變通道脈衝響應之實測資料。在比較Turin’s model 和空-時 model 後，發現群集因子在這兩個模型中對頻寬完全不同的特性；在Turin’s model 中K會隨頻寬增加而變大，然而由空-時模型得到的群集因子卻會隨頻寬增加而減少。這是因為在Turin’s model中多重路徑會因為在時間上的解析度增加，而從窄頻中的多重路徑再解析出更多的路徑，所以在接收訊號中可以觀察到多重路徑會有更明顯的群集效應，故此在Turin’s model 中群集因子會隨頻寬增加而變大。反之空-時模型中隨頻寬增加使空-時區塊變小，進而在接收訊號中可以觀察到一些原本無法在窄頻中觀察到的空時區塊，所以在寬頻訊號下看到多重路徑反而會擴散開來，因而減少群集因子的值。

Abstract In this paper, we use the modified Turin’s model to construct a novel impulse response. This model use the cluster factor to express the multipath clustering phenomenon , which is caused by the fact that scatters tend to group tighter, may become one of the dominant factors affecting the delay spread especially in the long delay situation. A method based on Turin’s △-K model is proposed to investigate and estimate the effect of radio bandwidth on the multipath clustering. It is found that the signal of larger bandwidth will observe stronger multipath clustering phenomenon because more paths can be resolved due to a finer time resolution. But in modified Turin’s model , it is found that larger signal bandwidth will observe weaker multipath clustering phenomenon more paths can be extended due to a finer time resolution. It is a interesting point that the cluster factor has the opposed relation with bandwidth in one dimension and two dimension Turin’s model. Our finding has been validated by the measurement result of 2.44GHz radio propagation in metropolitan , urban and suburban areas .