臺灣博碩士論文加值系統

這篇論文的主要目的是設計及硬體實現一個上鏈(uplink)通道寬頻分碼多工擷取(W-CDMA)系統的快速碼擷取(fast acquisition)系統。在寬頻分碼多工擷取系統中，實體隨機擷取頻道(PRACH)的前序碼(preambles)通常被使用作為傳輸初始同步的動作。由於特殊的前序碼結構，傳統匹配濾波器(matched filter)碼擷取架構需要很高的計算複雜度。在本篇論文中，吾人使用快速哈達馬轉換(Fast Hadamard Transform)來解決這個問題。在同樣的碼擷取效能上，快速哈達馬轉換能顯著的減低碼擷取系統中的計算複雜度。另外我們也使用雙重區塊(double dwell)搜尋技術來降低錯誤通報(false alarm)的機率。模擬的結果顯示出我們的設計在低訊雜比的環境中也能有很高的擷取正確機率。最後我們使用VHDL硬體描述語言與Xilinx FPGA的設計流程來實現我們設計的系統。

The purpose of this thesis is to design and implement a fast acquisition system for W-CDMA uplink transmission. In W-CDMA systems, preambles of the PRACH (physical random access channel) are used for initial synchronization. Due to the special preamble format, the conventional matched-filtering acquisition scheme requires high computational complexity. In this thesis, we employ a fast Hadamard transform (FHT) approach to solve the problem. While achieving the same acquisition performance, the FHT can significantly reduce the complexity of the acquisition system. To reduce the false alarm probability, we also use a double-threshold detection scheme. Simulations show that our design has high acquisition probability in low signal to noise ratio environment. Finally, we implement the system using VHDL hardware description language and the Xilinx FPGA design flow.

Abstract i
摘要 ii
Acknowledgements iii
Contents iv
List of Figures vii
List of Tables ix
CHAPTER 1 1
Introduction 1
CHAPTER 2 3
Acquisition Methods in DS/CDMA Systems 3
2.1 DS/CDMA Techniques 3
2.2 Synchronization in DS/CDMA Systems 5
2.3 Conventional Code Acquisition Techniques 6
2.3.1 Single Dwell Serial Search Technique 6
2.3.2 Multi-level Serial Search Dwell 7
2.3.3 Parallel Search 8
2.3.4 Hybrid Search 9
2.3.5 Match Filtered Code Acquisition 10
CHAPTER 3 12
Introduction to Wideband CDMA Systems 12
3.1 Introduction 12
3.2 Transport Channel 14
3.3 Uplink Physical Channel 16
3.3.1 Dedicated Uplink Physical Channel 16
3.3.2 Common Uplink Physical Channel 19
3.4 Code Generation and Allocation 20
3.4.1 Scrambling Code 20
3.4.2 Channelization Code 23
3.5 Uplink Spreading and Modulation 25
CHAPTER 4 28
Fast Acquisition Scheme 28
4.1 W-CDMA Uplink PRACH Descriptions 28
4.2 Hadamard-Walsh Transform 31
4.2.1 Built a Hadamard Matrix 21
4.2.2 Hadamard Matrix Propoties 34
4.2.3 Fast Hadamard Transform 36
4.3 Fast Acquisition Scheme Based on FHT 39
4.4 Performance Analysis and Simulation Results 41
CHAPTER 5 45
Hardware Design and FPGA Implementation 45
5.1 Design Flow 45
5.2 The PRACH transmitter 46
5.2.1 Long Code Generator 47
5.2.2 Complex-Valued Multiplier 48
5.2.3 Pulse Shaping Filter 50
5.3 Code Acquisition Part 52
5.3.1 Chip Matched Filter 53
5.3.2 RAM Array and Control Circuits 54
5.3.3 Fast Hadamard Transform 58
5.3.4 Maximum Selection 59
5.3.5 Search Controller 60
5.4 FPGA Implementation 62
5.4.1 The Transmitter Circuit 62
5.4.2 The RAM Control Circuit 63
5.4.3 The FHT and Related Circuit 66
5.4.4 The Control Circuit 66
5.4.5 Place and Route 67
CHAPTER 6 70
Conclusion 70
Reference 71

[1] R. L. Peterson, R. E. Ziemer, and D. E. Borth, “Introduction to spread spectrum communication,” Prentice-Hall, 1995.
[2] R. L. Pickholtz, D. L. Schilling, and L. B. Milstein, “Theory of Spread-Spectrum Communications-A Tutorial,” IEEE Trans. Commun., vol. COM-30, no. 5, pp. 855~883, May. 1982.
[3]. RAYMOND L. PICKHOLTZ DONALD L. SCHILING “Theory of
Spread-Spectrum Communications — A Tutorial” IEEE transactions on
communications, no.5, 1982
[4]. Rick, R.R.; Milstein, L.B.“Noncoherent parallel acquisition in CDMA
spread spectrum systems” ICC '94, SUPERCOMM/ICC '94, IEEE International
Conference on, pp: 1422 -1426 vol.3 1994
[5]. Briima B.Ibrahim and A. Hamid Aghami “Direct sequence spread spectrum
matched filter acquisition in frequency selective Rayleigh fading channels”
IEEE Journal on selected areas in communications vol.12 no.5, 1994
[6]. Mohamed G. El-Tarhuni, and Asrar U. Sheikh, “An adaptive filtering PN
code acquisition scheme with improved acquisition based capacity in DS/CDMA”
Personal, Indoor and Mobile Radio Communications, 1998. The Ninth IEEE
International Symposium on, pp. 1486-1490, 1998
[7]. 王逸婷/吳文榕“Adaptive Multi-user Acquisition for DS/CDMA System”
國立交通大學電信工程所, 2001
[8]. Hichan Moon,“Performance of double dwell acquisition with continuous
integration detector in a Rician fading channel” Spread Spectrum Techniques
and Applications, 1998 IEEE 5th International Symposium on, Vol. 1, 1998
[9]. Bensley, S.E.; Aazhang, B.“ Subspace-based channel estimation for code
division multiple access communication systems” Communications, IEEE
Transactions, Volume: 44 Issue: 8,1996
[10]. Madhow, U.“MMSE interference suppression for timing acquisition and
demodulation in direct-sequence CDMA systems” Communications, IEEE
Transactions, Volume: 46 Issue: 8 ,1998
[11]. El-Tarhuni, M.G.; Sheikh, A.U.H. “An adaptive filtering PN code
acquisition scheme with improved acquisition based capacity in DS/CDMA”
The Ninth IEEE International Symposium on, Vol. 3, 1998
[12]. Ling Qiu, Yongjia Huang, Jinkang Zhu.“Fast Acquisition Scheme and Implementation of PRACH in WCDMA System” Vehicular Technology Conference, 2001. VTC 2001 Fall. IEEE VTS 54th , Volume: 3 , 7-11 Oct. 2001.
[13]. Biqi Long; Hichan Moon “Detection and false alarm probability of PN code
acquisition in DS-CDMA system” Electronics Letters , Vol. 33 Issue: 11, 22 May
1997.
[14]. P. Chaudhury, W. Mohr, and S. Once, “The 3GPP Proposal for IMT-2000,” IEEE Commun. Mag. , vol. 37, pp. 72-81, Dec. 1999.
[15]. Harri Holma and antti toskala, Nokia, Finland, “WCDMA for UMTS” Wiley, 2000.
[16]. Tero Ojanpera, Nokia Research Center and Ramjee Prasad, Delft University of Technology, “An Overview of Air Interface Multiple Access for IMT-2000/UMTS,” IEEE Commun. pp. 82~95, Sept. 1998.
[17]. Technical Specification 3Gpp TS 25.211 V4.1.0 (2001-06)
[18]. A. Amira, A. Bouridane, P. Milligan, M. Roula “Novel FPGA implementations of Walsh-Hadamard transforms for signal processing” Vision, Image and Signal Processing, IEE Proceedings- , Volume: 148 Issue: 6 , Dec. 2001 Page(s): 377 -383