室內平坦快速衰落無線通信頻道之Rician Factor研究

Abstract

本論文吾人提出一種最新發展的模式,它結合二維適應環境模式與隨機 散射統計模式所組成的合併模式.其目的在探討室內環境下平坦快速衰落 無線通信頻道的 Rician Factor.一般統計模式被用來描述由於任意擺放 之散射體與粗糙表面邊界所造成之散射場分量.在吾人的合併模式中,發現 經常被忽略之散射場的確有足夠之效應去影響 Rician Factor 的分佈,而 這個效應的大小,吾人用一個比例值 r 來表示.在吾人的合併模式中,提出 一個精確又合理的 Rician Factor 預估值,對於較大的 r 值,代表有較強 的散射場和較小的 K 值.此種情況經常發生在周遭環境有很大的散射物體 或者是在非視線傳播的環境中. A newly developed hybrid model,composed of a two- dimensional(2-D)site-specific model and a randomly scattered model,is employed toinvestigation the Rician Factor of indoor flat fast fading channels.In our model,the averaged scattered( diffused)envelop,which has a significanteffect on the Rician Distribution and is usually neglected,can be effectivelyquantified by a ratio factor r. With a proper chosen value of r,our model yields a reasonable prediction accuracy of the Rician factor. It is foundthat a larger value of r represents a stronger scattered field and yields a small value of K,which is usually happened at the sites with heavy surroundingclutters or in NLOS(non Line-Of-Sign)propagation situations.