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研究生:周書漢
研究生(外文):Shu-Han Zhou
論文名稱:混成碼分多址/波分多址系統中之窄頻干擾抑制
論文名稱(外文):Narrowband Interference Suppression in a Hybrid CDMA/WDMA System
指導教授:張伯浩
指導教授(外文):Po-Hao Zhang
學位類別:碩士
校院名稱:國立東華大學
系所名稱:電機工程學系
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:英文
論文頁數:89
中文關鍵詞:分碼多工分波多工雜訊抑制液晶
外文關鍵詞:NarrowbandInterference SuppressionCDMAWDMA
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近年來有線網路的頻寬與傳輸容量的需求與日俱增,這是因為網路的普及化與低價電腦推動的成果。目前全球上網人口眾多,對於網路品質(保密、穩定度..等等)與多媒體(影音、及時性資料傳輸…等等)的要求提高,使得目前頻寬與容量已經無法滿足需求。
有鑑於此,光纖傳輸因應現代需求,首先發展出WDMA(Wavelength Divided Multiple Access) 系統,目前也已經成熟地應用在商業之中,雖然WDMA可以舒解頻寬的需求,但是WDMA的頻寬利用效率不佳(對於高頻寬的光纖系統來說),因此發展出OCDMA(Optical Code Divided Multiple Access)系統,用來彌補WDMA的缺點,而我們的系統就是根據OCDMA/WDMA的架構下,針對傳輸效能(transmission performance)的改善來研究。
本論文的重點是:接收經由OCDMA/WDMA系統傳送過來的訊號,擷取OCDMA使用者訊號,排除WDMA使用者訊號。我們重新設計一個修改型液晶調變器(modified liquid crystal modulator)代替原來的液晶調變器,達到抑制WDMA的影響,此方法同時可以將MAI(Multiple Access Interference)的影響降低,因此對整體效能(performance)來說,有不錯的改善。
In recent years, the requirement of the bandwidth and capacity for wired network keeps increasing because of the easy-access network and low-cost computer. The pursuit of quality (security, stable, etc.) and the use of multimedia (video, real-time transmission etc.) also mean that today’s bandwidth and capacity cannot meet the demand.
On the other hand, the optical transmission meets the demand. For the optical communication, the WDMA (Wavelength Divided Multiple Access) system has been developed at first and maturely commercialized. Although WDMA can be used to satisfy the requirement, it has the disadvantage of low efficiency in utilizing bandwidth (for the high bandwidth optical communication system). Thus, the OCDMA (Optical Code Divided Multiple Access) is developed in order to compensate for the disadvantage of WDMA. Furthermore, our system is based on the hybrid system of OCDMA+WDMA, and our research focuses on improving the transmission performance.
In the thesis, we access an OCDMA user’s signal as the desired signal and view WDMA users as narrowband interference. Our research is to suppress or reject the WDMA signals. We redesign the pixels of liquid crystal modulator, and use this modified liquid crystal modulator (modified LCM) to replace the original liquid crystal modulator (original LCM) so that the interference of WDMA signals will be suppressed. In addition, our approach also suppresses the effect of MAI (multiple access interference). For the performance of the entire system, it is obviously improved.
摘要 i
Abstract iii
Acknowledgement iv
Contents v
List of Tables and Figures vii

Chapter 1 Introduction 1
Chapter 2 Fundamental Theory 4
2.1 Fundamental Properties of Light 4
2.2 The Statistic Light in Mode-Locked Laser 7
Chapter 3 The OCDMA and WDMA Communication Systems 12
3.1 Introduction 12
3.2 The fs Laser 12
3.2.1 Mode-Locking 12
3.2.2 Devices of the fs Laser 14
3.2.3 Round-Trip Model and Evolution of the Pulse Energy 17
3.2.4 Passive Mode-Locking Dye Laser with the Round-
Trip Mode 18
3.2.5 Passively Mode-Locked Semiconductor Lasers 19
3.2.6 Other Techniques of fs Lasers 20
3.2 Pulse Shaping 20
3.3.1 Liquid Crystal Phase Modulator 21
3.3.2 Phase Change 22
3.3.3 Pulse Shaping (Pulse Modulation) 24
3.3 OCDMA System 28
3.4 WDMA 33
Chapter 4 Interference Suppression of the Hybrid
OCDMA/WDMA Communication System 40
4.1 Introduction 40
4.2 Our Approach to the Suppression of Interference
by WDMA 41
4.2.1 Failure Experiments 41
4.2.2 The Appropriate Approach 43
4.3 OCDMA/WDMA System Model 44
4.4 Performance Analysis 46
4.4.1 BER analysis 50
4.4.2 Computer simulation result 54
4.4.3 Conclusion 57
Chapter 5 Conclusion 75
Bibliography 77
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