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研究生:李志宏
研究生(外文):Chih-Hung Lee
論文名稱:寬頻CDMA系統在高速移動環境下之效能分析
論文名稱(外文):Performance Evaluation for WCDMA System under High-Speed Mobile Environments
指導教授:李學智李學智引用關係
學位類別:碩士
校院名稱:國立臺灣大學
系所名稱:電信工程學研究所
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:2005
畢業學年度:93
語文別:英文
論文頁數:91
中文關鍵詞:第三代行動通訊寬頻分碼多工存取無線通道特性高速移動環境卜勒偏移補償卜勒暫態
外文關鍵詞:3GWCDMAWireless channel characteristicsHigh-speed mobile environmentDoppler shift compensationDoppler transient
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隨著高速行動通訊服務的需求增加時,第三代行動通訊系統應用於高速火車上之研究將變得是不可或缺的。本篇論文主要是探討寬頻CDMA 系統在高速移動環境下之傳輸效能。由於考慮載波同步及通道估測的效應而導致系統效能因都卜勒過度偏移(over Doppler shifting)的問題而降低。為了改善系統效能,我們提出一種稱為都卜勒偏移補償(Doppler shift compensation)的方法來克服因為載波同步後所造成的都卜勒過度偏移的問題。在本論文中,我們就所提出的方法及傳統線性內差的通道估測方法推導出各別的通道估測的均方差;並且證明出當K 因子很大時,我們所提出的方法將有極大的改善。基於所提出的接收機架構並且考慮了載波同步及通道估測的效應下,我們去分析了寬頻CDMA 系統在高都卜勒衰落通道下的系統效能。模擬結果也顯示出我們所提出的方法比傳統的方法更能改善系統效能且提高通訊品質。此外,我們也展示出不論都卜勒暫態(Doppler transient)效應有多大,鎖相迴路都能去鎖定耙式(RAKE)接收機的等一個finger。然而,當都卜勒的改變率很大時,此時耙式接收機如果結合更多的fingers 將會導致系統效能的降低。
As the demand of wireless communication services for high-speed mobile stations is increasing, the researches on the wireless mobile communication systems such as 3G WCDMA system utilized for high-speed trains (HST) will become more indispensable. In this thesis, we investigate the transmission performance for WCDMA system under the high-speed mobile rural area environments. Carrier synchronization and channel estimation are usually imperfect and the system performances are degraded due to the over Doppler shifting (ODS) problem. In order to improve the system performance, we propose a method, called the Doppler shift compensation (DSC), to overcome the ODS problem. We derive the mean square error (MSE) of the channel estimation by the conventional linear interpolation method and by our proposed approach. We found that our proposed approach has a tremendous improvement when the K factor is large. Based on the proposed receiver structure, we analyze the system performance for WCDMA system and compare it with that obtained by the conventional receiver in various high-Doppler multipath fading channels, where we have taken into account the effect of carrier recovery and imperfect channel estimation. Besides, we also demonstrate that no matter how large the Doppler transient is, the PLL can track the first finger well. However, when the change rate of Doppler frequency is very large, combining more fingers degrades the system performance for both the conventional and our proposed method.
Abstract Ⅰ
Contents Ⅲ
List of Figures ⅤI
List of Tables IX
Chapter 1 Introduction……………………………………...………….…………1
1.1 Overview of Mobile Communication Systems 1
1.2 Motivation 2
1.3 Organization of the Thesis 3
Chapter 2 Wireless Channel Characteristics and Channel Models……..5
2.1 Introduction 5
2.2 Rayleigh Fading Channel 6
2.2.1 The Doppler Effect 7
2.2.2 How to generate the Rayleigh fading signal 8
2.3 Ricean Fading Channel 11
2.3.1 How to generate the Ricean fading signal 12
2.4 Wideband Fading Channel 14
2.5 Geometry-Based Wideband Channel Model 15
2.5.1 How to generate the geometry-based wideband vector channel 18
Chapter 3 Investigations on Carrier Synchronization and Channel Estimation in High Speed Railway Environment………...….23
3.1 The Issues for High Speed Railway Environment 24
3.1.1 Fast Fading Environment 24
3.1.2 Doppler Effect and Doppler Transient 25
3.2 Carrier Synchronization 27
3.2.1 The Basic Concept of Phase-Locked Loop 27
3.2.2 The Costas Loop 28
3.2.3 The Modified Costas Loop 30
3.3 Performance Evaluation in High Speed Ricean Channel 32
3.3.1 Simulation results 37
3.4 Performance Evaluation in High Speed Two Ray Ricean Channel 42
3.5 Summary 47
Chapter 4 The Specification of Wideband CDMA System in
Third Generation……………………………………………………..49
4.1 The Uplink Physical Dedicated Channel 51
4.1.1 The Frame Structure 51
4.1.2 Spreading and Modulation 52
4.2 The Downlink Physical Dedicated Channel 56
4.2.1 The Frame Structure 56
4.2.2 Spreading and Modulation 57
4.3 Channel Coding 59
Chapter 5 Performance Evaluation for WCDMA System under High Speed Mobile Environments…………………………………….....61
5.1 The Problem for High-Speed Multipath Channel due to Carrier Recovery 62
5.2 Proposed Method: Doppler Shift Compensation 64
5.2.1 Performance Analysis 65
5.3 Calibration of Noise 69
5.4 Numerical results 71
5.4.1 Wideband Multipath Channel Model 72
5.4.2 Geometry-Based Wideband Channel Model 77
5.4.3 Performance in coded system 80
5.5 Simulation results for Doppler Transient 83
Chapter 6 Conclusion……………………………………………………………87
References………………………………………………………………………….89
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[2] S. R. Saunders, Antennas and Propagation for Wireless Communication systems, John Willy & Sons, 1999.
[3] J. K. Cavers, Mobile Channel Characteristics, Kluwer Academic Publisher, 2000.
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[5] http://gsm-r.uic.asso.fr
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[7] http://www.cordis.lu/infowin/acts/home.html
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[10] Roland E. Best, Phase-Locked Loops: theory, Design and Applications, 4th Edition, New York: McGraw-Hill, 1999.
[11] John G.. Proakis, Digital Communications, 4th Edition, New York: McGraw-Hill, 2001.
[12] Jen-Shi Wu, Ming-Luen Liou, His-Pin Ma, Tzi-Dar Chiueh, “A 2.6V 44-MHz All-Digital QPSK Direct-Sequence Spread-Spectrum Transceiver IC”, IEEE J. Solid-State Circuits, vol. 32, No. 10, October 1997.
[13] Mirabbasi S., Gazor S., and Martin K., “A Wideband Carrier Recovery System for Multilevel QAM Signals”, IEEE ISCAS 2000, vol. 4, May 2000.
[14] http://www.3gpp.org/
[15] Harri Holma and Antti Toskala, WCDMA FOR UMTS: Radio Access For Third Generation Mobile Communications, John Wiley, 2000.
[16] 3GPP TSG RAN, “UE Radio Transmission and Reception (FDD)”, TS 25.101 v6.5.0, Step. 2004.
[17] 3GPP TSG RAN, “BS Radio Transmission and Reception (FDD)”, TS 25.104 v6.7.0, Step. 2004.
[18] 3GPP TSG RAN, “Physical Layer – General Description”, TS 25.201 v6.0.0, Dec. 2003.
[19] 3GPP TSG RAN, “Physical Channels and Mapping of Transport Channels onto Physical Channels (FDD)”, TS 25.211 v6.2.0, Step. 2004.
[20] 3GPP TSG RAN, “Multiplexing and Channel Coding (FDD)”, TS 25.212 v6.2.0, June 2004.
[21] 3GPP TSG RAN, “Spreading and Modulation”, TS 25.213 v6.0.0, Dec. 2003.
[22] 3GPP TSG RAN, “Physical Layer Procedures (FDD)”, TS 25.214 v6.3.0, Step. 2004.
[23] Long Qian and Stevan Berber,” 3G WCDMA Design, Simulation and Analysis Using Ptolemy Software Tools ”, IEEE ICICS-PCM 2003, vol. 2, pp. 897-901, Dec. 2003.
[24] Fakhrul Alam,” Simulation of Third Generation CDMA Systems”, Master’s thesis, Virginia Polytechnic Institute & State University, 1999.
[25] Bjerke B. A., Zvonar Z., and Proakis J. G., ”Antenna Diversity Combining Schemes for WCDMA in Fading Multipath Channels”, IEEE Trans. on Wireless Comm., vol. 3, pp. 97-106, Jan. 2004.
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