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標題: 直序展頻分碼多工系統適應性單用戶接收機之分析
Analysis of Adaptive Single-User Receivers for DS-CDMA Systems
作者: 洪明輝
Hung, Ming-Hei
關鍵字: Adaptive receivers;適應性接收器;capacity;DSSS-CDMA;multiple-access interference;near—far problem;spreading code;RAKE receiver;LCL;系統性能;直接序列展頻分碼多工;多重接取干擾;遠近的問題;展頻碼;靶式接收器;相互線性共軛性
出版社: 電機工程學系
本論文展現在二位元相位鍵位移直接序列展頻分碼多工系統(BPSK DSSS-CDMA)中,單一用戶適應性接收機能執行解展頻、抑制碼際干擾(InterSymbol Interference, ISI)、解決多重接取干擾(Multiple Access Interference, MAI)及遠近的問題(near-far problem),有些甚至能夠被當成靶式(RAKE)接收器;我們將改善這些單一用戶適應性接收機的架構應用於四分相相位鍵位移(QPSK)的調變信號;並且將改善後之性能作分析與比較。
本篇研究亦針對在二位元相位鍵位移直接序列展頻分碼多工系統中,應用黃金碼(Gold code)及沃爾什碼(Walsh code)兩組不同展頻碼組於單一用戶適應性接收機上,觀察並比較他們對整個系統性能的影響。
結果顯示在所有適應性接收機中,無論是在二位元相位鍵位移或四分相相位鍵位移的調變信號下,相互線性共軛(Linear-Conjugate Linear, LCL)形式的適應性接收機都有著最佳的性能表現。另外我們也知道沃爾什碼(Walsh code)適用於無線通信基地台內部的攪拌動作;而黃金碼(Gold code)卻適合被當作虛擬雜訊碼(PseudoNoise PN code)在基地台及手機上去做信號展頻的動作。

The paper represents that adaptive single-user receivers can perform despreading, intersymbol interference (ISI) rejection, the near—far resistance, multiple-access interference (MAI) rejection and in some cases act as a RAKE receiver for the Binary Phase-Shift Keying direct-sequence spread-spectrum code-division multiple access (BPSK DSSS-CDMA). These receivers based on BPSK DSSS-CDMA are developed for Quadrature Phase-Shift Keying (QPSK) modulated signal and their performances will be analyzed and compared with BPSK's.
The capacity of BPSK DS-CDMA system is affected by the properties of the spreading code. The other goal of the research is to perform adaptive single-user under the Gold and Walsh code as spreading code set for this system. The effectiveness of the capacity used different spreading code sets also should be presented and compared.
The conclusions indicate, for BPSK and QPSK, the Linear-Conjugate Linear (LCL) form of adaptive filter is the optimum receiver among all adaptive single-user receivers. And Walsh code is only used in combination with scrambling codes within the base station of a cellular communication system. The Gold code can be viewed as the PseudoNoise (PN) code to spread spectrum data signal for the base station and the mobile of a cellular CDMA system
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