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研究生:陳政謙
研究生(外文):Zheng Qian Chen
論文名稱:分碼多工多使用者偵測方法的改良
論文名稱(外文):Modified CDMA Multiuser Detection
指導教授:謝世福
指導教授(外文):Shin-Fu Hsieh
學位類別:碩士
校院名稱:國立交通大學
系所名稱:電信工程系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2002
畢業學年度:90
語文別:中文
論文頁數:76
中文關鍵詞:分碼多工多使用者偵測
外文關鍵詞:CDMAMultiuser Detection
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直接序號的分碼多工是分碼多工這個領域最熱門的無線通訊技術,在直接序號的分碼多工通訊系統裡,每個使用者所使用的傳輸信號再同一個時間同一個頻率上重疊在一起,彼此照成了相互間的干擾。
為了克服彼此間相互的干擾,我們採用匹配濾波器的輸出和MMSE的理論,當使用者時常的變動的情形下,為了避免去計算大的反矩陣,我們回顧和使用分群概念,我們回顧GSIC的理念它一個群組一個群組去偵測並用SIC的方法順序去消除群組的干擾,我們同時發展出GPIC和GISIC。
在GPIC中,我們同時的偵測所有群組並使用PIC的架構去消除群組間的干擾。在GISIC,中我們改變兩級GSIC的第二級的偵測順序。除此之外,回顧之前的MMSE所做的群組偵測方法,我們把群組之間的干擾考慮進來,改良了MMSE的群組偵測方法。最後我們用電腦模擬的方法去比較我們所發展出來的方法。

Direct-Sequence Code-Division Multiple Access (DS-CDMA) is a most popular wireless technology in CDMA communication, and all of the users' signals overlap in time and frequency and cause mutual interferences.
We use the MMSE detection to overcome the interferences, but when users change frequently, we review and use the group concept to avoid calculating large matrices inverses. We review the Group Successive Interference Cancellation (GSIC) group detection concept which detects each group one by one, and use the SIC scheme to cancel intergroup’s interferences, and we develop Group Parallel Interference Cancellation (GPIC) and Group Iterative Successive Interference Cancellation (GISIC) methods. In GPIC, we detect each group at once, and cancel intergroup’s interferences by using the PIC scheme. In GISIC, we modify two stages GSIC and make the second stage to have reverse detection direction. Besides that, we modify the MMSE group detection function by considering the intergroup’s interferences. Finally, we compare the performances of those detectors in computer simulation.

Contents
1 Introduction 1
2 BACKGROUND 6
2.1 Direct Sequence Code-Division Multiple-Access Channel 6
2.1.1 Basic Synchronous CDMA Model 6
2.1.2 Discrete-Time Synchronous Model 8
2.1.3 Matched Filter Outputs 9
2.2 Conventional Detector 10
2.3 Optimum Multiuser Detection 11
3 Suboptimal CDMA Multiuser Detectors 14
3.1 Decorrelating Detector 14
3.2 Minimum Mean-Square Error (MMSE) Linear Multiuser Detector 18
3.3 Decision-Driven Multiuser Detectors 20
3.3.1 Successive Interference Cancellation 20
3.3.2 Multistage Detection 23
4 Modified Group Multiuser Detectors 26
4.1 Group Successive Interference Cancellation (GSIC) Detection 26
4.1.1 GSIC Group Detection Scheme 27
4.1.2 Multi-stages GSIC 30
4.1.3 The Group Detection Function of 31
4.2 The Group Parallel Interference Cancellation (GPIC) Multiuser Detection 33
4.2.1 The structure of GPIC Multiuser Detection 33
4.2.2 The Group Detection Function of 35
4.2.3 MMSE of Group Detection Function 36
4.2.4 Comparison Between First Stage GPIC and MMSE Detector 40
4.2.5 Multistage GPIC Multiuser Detector 42
4.3 Group Iterative SIC ( GISIC) Multiuser Detector 44
4.3.1 The Iterative Successive Interference Cancellation 44
4.3.2 The GISIC structure 41
4.3.3 The Group detection function 52
4.3.4 The multistages GISIC multiuser detector 54
4.4 The Comparison Between GSIC, GPIC and GISIC 57
5 Computer Simulation 59
5.1 Generation of PN Sequences 59
5.2 The Iterative Successive Interference Cancellation 61
5.3 The Group PIC Multiuser Detector 63
5.4 Three stages Group PIC multiuser detection 65
5.5 The Group Iterative SIC Multiuser Detector 70
6 Conclusions 75

Bibliography
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Page(s): 121 -126 vol.1

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