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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/44414
標題: | 應用向量化/平行化技巧加速之電波射線追蹤程式 A Ray-Tracer Accelerated by Using Vectorization/Parallelization Techniques for Propagation Modeling |
作者: | Chang-Yu Tseng 曾昶宇 |
指導教授: | 鄭士康(Shyh-Kang Jeng) |
關鍵字: | 向量化,平行化,幾何光學, Vectorization,parallelization,geometrical optics, |
出版年 : | 2009 |
學位: | 碩士 |
摘要: | 電信工程領域所使用之射線追蹤程式(Ray-tracing Program)是用於無線通道特性之預測,例如通訊環境裡場強之分佈預測,可作為發射基地台規劃之用。但由於射線追蹤通常係用於處理運算量較大之通訊傳播問題(尤其是多次反射、透射效應明顯的通訊環境),若能應用一些提高計算效率的技巧於程式中,將會節省更多的執行時間。故本論文旨在將電波傳播模擬程式,做適當的平行處理以及向量化運算,以增進其計算之效率,並對此二種加速技巧進行效能改善程度之分析。
所發展之射線追蹤模擬程式,是將發射天線所輻射出之電磁波近似為幾何光學特性,亦即考慮直接波、反射波與透射波等多重路徑干涉,搭配電磁波傳播之強度衰減、相位變化等理論作為基礎發展而成;並將射線柱對所有接收點(或者接收天線)之貢獻加總,可得總接受功率。 為提高射線追蹤之效率,搭配叢集式電腦(PC cluster)將發射天線對各方向輻射之電磁波(initial ray tubes)進行平行追蹤;另外,對於射線行進時將會抵達之交界面的判斷(ray-facet test),以及單一射線柱對所有接收點之貢獻,我們運用了向量式程式語言MATLAB中的矩陣運算,以提高程式之執行效率。並藉由模擬若干文獻上之通訊環境,與該文獻上之模擬結果相比較以確保程式之可靠性。 最後藉由實際測量執行時間之結果可知,我們所發展之射線追蹤程式,就向量化運算對效能之影響而言,接收天線個數之固定增量以及三角形平板個數之固定增量分別對執行時間產生固定之微小增量(即天線個數或三角形平板個數與運算時間呈線性(非正比)關係);而經由平行處理後所獲得之加速(speedup)倍數,於一般通訊環境之模擬,可接近於所使用之處理器數目,效率(efficiency)亦可達到75%以上。 In this thesis, a ray-tracer with vectorization/parallelization for radio wave propagation modeling is presented. This approach applies the ray tube tracing method to compute the field or power distributions made by a transmitter among all receivers. All ray tubes launched from a transmitter are traced transmitting and reflecting in the environments and each E-field contribution made by ray tubes to all receivers are summed up to calculate the power densities. In order to speed up our program, vectorization and parallelization techniques are introduced. The former is applied to all receivers and all triangular facets; the latter is applied to all initial ray tubes. To verify our ray-tracing program, six scenes/environments reported in previous works of others are simulated by our program and the results are compared with those presented in the previous literatures. All agreements are acceptable. Finally, several performance measurements are conducted. For vectorization, the execution time of E-field computation/ray-facet test function just has a slightly linear increment with increasing number of RX’s/triangular patches; for parallelization, in a common 3D propagation environment, the speedup can be close to the number of applied processors, and the efficiency can be at least 75%. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/44414 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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