Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/7847
標題: 盲蔽式適應性直接序列展頻濾波器 應用於多路徑衰減通道
Blind Adaptive DS/CDMA Receivers in Multipath Fading Channels
作者: 陳柏羽
Chen, Po-Yu
關鍵字: CDMA;分碼多工;multipath;blind;GSC;多重存取干擾;盲蔽式;廣義旁波瓣消除
出版社: 電機工程學系
摘要: 
在分碼多工多使用者存取的通訊系統之中,訊符間干擾(Intersymbol interference)及多重存取干擾(Multiple-access interference)均是非常重要的議題。在多重使用者分碼多工的行動通訊系統中,因為時變性多重路徑的通道會造成嚴重的干擾,而使得系統容量下降。傳統的濾波器必須作出適當的改良來克服多路徑所造成的衰減,本篇論文提出四種適應性濾波器的架構來解決上述的問題,並且我們提出一種新的理論,其概念是使得適應性濾波器所估測出來訊號的能量去逼近所要求的訊號能量. 我們稱為這新的理論為Variance-Oriented Approach (VOA),並且把VOA這一個新的演算法分別套用在有限脈衝響應(Finite Impulse Response)濾波器、無限脈衝響應(Infinite Impulse Response)濾波器、可調式解展頻濾波器(Despreader Filter)以及本篇主要提出的廣義旁波瓣消除濾波器(GSC Filter)架構上。廣義旁波瓣消除濾波器原本是用於空間上,為了消除其它入射角度的干擾訊號方法。在此我們將此概念轉而應用於時域上,使得有效抑制多使用者所造成的多重存取干擾。模擬的部分,包含了不同架構系統效能的比較,進而分析在不同的環境中而顯現其各自的優劣性。

In order to eliminate multiple-access interference (MAI) and intersymbol interference (ISI) in direct sequence code division multiple access (DS/CDMA) multiuser communication systems, in this paper, we propose several receiver structures and employ the property of the discreteness of the input data symbol to derive the blind algorithms. These proposed adaptive receivers are updated in symbol-interval so their computational loading is lower than the chip-interval based adaptive receivers. We use the concept that the variance of despreading result approach to the variance of desired signal to be the cost function. We call this new algorithm as Variance-Oriented Approach (VOA), and we apply VOA to each proposed scheme with CDMA system. Especially, we apply the Generalized Sidelobe Canceller (GSC) scheme, that is generally the concept of spatial domain in beamforming system, to eliminate the MAI by one particular constraint in temporal domain. Simulation examples are shown to demonstrate the effectiveness and comparison of the proposed blind adaptive receivers.
URI: http://hdl.handle.net/11455/7847
Appears in Collections:電機工程學系所

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