利用干擾投影之具通道估測與續列干擾消除多用戶偵測器

Using Interference Projection Method in Channel Estimation SIC Multiuser Detector

廖怡如(Yi-Ju Liao)

指導教授 ： 陳文良

國立清華大學/工學院/動力機械工程學系/碩士(2006年)

摘要

近幾年來，由於分碼多工存取系統(CDMA)比分時多工存取系統(TDMA)擁有較高容量、能抵抗多重路徑之衰減等許多優點，已成為一重要之通訊機制與實現3G無線網路系統的基本方法。然而，在傳送訊號時受到多重路徑影響的關係，使得接收端在接收某個傳送訊號時會因此接收到不同時間延遲，不同振幅衰減的加成訊號，進而造成解調還原時工作的困難。另一個造成干擾的原因則為多重存取干擾(MAI)，是由於在CDMA系統中，多位使用者同時在相同的頻帶上傳送訊息所造成。為了要消除這些干擾，數種多用戶偵測器曾被提出，其中包含了續列干擾消除偵測器(SIC)。在此論文中，我們提出與通道估測相結合之續列干擾
消除偵測器。
現在已有一些通道估測的方法被提出，如利用最小平方法(least-square procedure)和最陡坡降遞迴調整法則(steepest-decent recursive adaptation rule)所提出之通道估測。本文將提出一個結合此通道估測方法與干擾投影法之干擾消除接收器。比起原本的干擾消除接收器，我們不需知道用戶的傳送功率與傳送通道參數，即可解調出用戶傳送的訊號。因此本文提出的此種接收器明顯的更合乎實際上的通訊狀況。經過數據模擬驗證，此接受器的效能仍維持在不錯的範圍內。

關鍵字

續列干擾消除多用戶偵測器

並列摘要

Code Division Multiple Access (CDMA) becomes an important access scheme in recent years because of its several advantages such as higher capacity, anti-jamming. It also has emerged as the basic technique for the realization of the physical layer of third generation (3G) wireless network. However, because of the multipath fading effect, the receiver will receive many replicas of the transmitted signal. These replicas arrive at the receiver with slightly time differences and amplitude decay. This will cause the problem in demodulating received signal. Another source of interference is the multiple access interference (MAI) which is produced when there are multiple users using the same frequency band simultaneously in the CDMA system. In order to suppress the interference, several multiuser detectors have been proposed, including the successive interference cancellation (SIC) scheme. In this thesis, an algorithm is proposed, which combines the interference cancellation scheme with channel
estimation.
Some channel estimation methods have been proposed , e.g. the channel estimation by least-square method and steepest-descent recursive adaptation rule. In this thesis, an interference cancellation receiver incorporating the channel estimation method and the interference projection is introduced. Compared to original interference cancellation receiver, we can demodulate the information signal under the unknown power of transmitted signal and channel function. So, the receiver we proposed is clearly more fit the practical communication situation. After the
simulation, this receiver can still hold a good performance.

參考文獻

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