室內無線電通道多重路徑模型之建構

Abstract

本論文提出新的合併模式，該模式可用來研究室內無線電波多重路徑衰落的特性。它是由二維適應環境模式(Site-Specific Model)和散射模式所組合而成，適應環境模式可包含由內部牆壁所造成的平均功率衰減或徑路損失，這可能會造成遮蔽效應。後者模式則用來描述由隨機擺放的散射體或粗糙表面邊界，以及經牆壁多次反射穿透等造成的散射場，合併模式將可減少適應環境模式中射線追跡的樹狀階層數，進而大量節省計算時間。合併模式不單可精確地預估平均場強值，還藉由參數r有效地量化室內環境中散射場分量相對平均值的貢獻。不同地點的大量實驗數據（2.44-GHz）顯示Nakagami分佈可以有效的描述室內的衰落分佈（Fading distribution）。再經由進一步的blind測試，可確認合併模式的預估效果。

This study presents a novel and efficient hybrid model based on a two-dimensional (2-D) site-specific model and a scattered model to characterize the multipath fading in indoor environments. The site-specific model includes the average signal power attenuation or path loss due to interior wall obstruction, which may lead to shadow fading. The latter model characterizes effect of scattering due to rough surface boundaries and/or randomly positioned scatterers and effect of higher-order multiple reflections or transmission-reflections due to walls, which significantly affects small-scale fading. It is found that this treatment can decrease the number ray-tree levels of the site-specific model and saves a lot of computational time. In addition to accurately predicting mean field strength, the hybrid model can effectively quantify the relative mean contribution of diffused scattering with a factor r. A large amount of experimental data for 2.44-GHz radio at many different sites shows that a Nakagami distribution describes the fading distribution well. Some blind tests validate the effectiveness of the model.