臺灣博碩士論文加值系統

數位電視為未來的趨勢已不容置疑，現在有很多國家已設定數位電視廣播之開播時間表，並設定電視需含數位接收裝置之百分比及時間表。目前歐規數位電視廣播採用OFDM 作為傳輸規格,經過很多的測試, 均證實OFDM 是個很好的傳輸方式。由於OFDM具有抵抗頻道衰退以及抗多重路徑干擾之優點，因此4G亦正針對此一特性準備採用作為其傳輸規格。
但由於OFDM之訊號為多個子載波所組成，因此其高峰值對平均值能量比便為其一大問題點。科學家們發明了各種不同理論如直接裁減、編碼方式、及改變編碼結構等；現今由於DSP之技術不斷更新，DSP運算速度越來越快,價錢也不斷的下降,因此改變編碼結構的方式越來越受到重視。
本篇論文中，我們將OFDM 傳送接收系統作一些說明, 並對於減少OFDM PAPR 的技巧作簡短的討論.最後針對SLM之改變編碼結構方式，如不同的相位序列作模擬測試，另根據不同的相位序列cluster 數目討論然後分析找出最好的組合。

It is no doubt that the Digital Television (DTV) is the future trend. Now there are a lot of countries announced the DTV broadcasting schedule, and the schedule of import television with DTV receiver device. Now the Europe DVB-T adopted the OFDM as the transmission scheme. In Taiwan, Tatung University have fulfilled some field test to prove that the OFDM technology is better than 8-VSB when applying for mobile devices. Due to OFDM system has the following characteristic, such as anti channel fading and anti multi-path interference, 4G system also want to adopt the OFDM as it’s transmission specification.
But OFDM signal is composed by several multi-carriers, it’s peak power will degrade it’s system battery life. Scientists develop several algorithms to reduce the PAPR such as clipping theory, coding technology, and scrambling algorithm. Now the SLM and PTS scrambling technology are more and more important as consequence of the improvement of DSP technology.
In this thesis, an overview of OFDM system is presented. The schemes of reduction OFDM PAPR are discussed briefed. We focus on the different schemes of SLM scrambling such as different phase sequences, and we also discussed the best combination between different phase sequences and different clusters.

Page
ABSTRACT(in Chinese)---II
ABSTRACT(in English)---III
ACKNOWLEDGEMENT---IV
CONTENTS---V
LIST OF FIGURES---VII
LIST OF TABLES---IX
CHAPTER 1 INTRODUCTION---1
1.1 Review of Background---1
1.2 OFDM History---2

CHAPTER 2 An Overview of OFDM---3
2.1 Multi-carrier Transmission and Orthogonal Consideration---3
2.2 OFDM System Description---5
2.2 Guard Interval for OFDM System---7
2.3 Peak Power Problem of OFDM System---9

CHAPTER 3 PAPR Reduction Theory---12
3.1 OFDM PAPR Character---12
3.2 Using CCDF to do OFDM PAPR Statistic---13
3.2.1 Introduction of CCDF---13
3.2.2 OFDM CCDF Curves---14
3.2.3 Statistical Origin of CCDF Curves---15
3.3 Clipping and Peak Windowing Theory---16
3.4 Coding and Scrambling for OFDM after PAPR Reduction ---19
3.5 Peak Cancellation Theory---20
3.6 Coding Technology to Reduce PAPR---24
3.6.1 Introduction of Coding Technology---24
3.6.2 Complementary Sequence Theory---24
3.6.3 Block Coding Scheme for the Reduction of the PAPR---25
3.7 Partial Transmit Sequence Scheme (PTS)---27
3.7.1 Introduction of PTS---27
3.8 Selective Mapping Scheme (SLM)---31
3.8.1 Introduction of SLM---31
3.8.2 Side Information---33
3.8.3 SLM Benefit---33

CHAPTER 4 Simulation and Performance Evaluation---34
4.1 Simulation and Algorithm---34
4.2 Simulation Result and Performance---37
4.2.1 Random Sequences---37
4.2.2 Conclusion---38
4.2.3 Walsh-Handamard Sequences---39
4.2.4 Conclusion---42
4.2.5 Golary Complementary Sequences---42
4.2.6 Conclusion---44
4.2.7 The Performance Comparison Between Random Sequences, Walsh-Handamard Sequences, and Golary Complementary Sequences---45

CHAPTER 5 CONCLUSIONS---48

REFERENCES---49

[1] Leonard J., Cimini Jr., and Nelson R. Sollenberger, “Peak-to-Average Power Ratio Reduction of an OFDM Signal Using Partial Transmit Sequences”, IEEE Comm. Letters, Vol. 4, No. 3, pp.86-88, March 2000.
[2] Imran Ali Tasadduq and Raveendra K. Rao, “Weighted OFDM with Block Codes for Wireless Communication”, in IEEE Pacific Rim Conference on Communications,Victoria BC, Canada, Aug. 26-28, 2001, pp.441-444.
[3] Pingyi Fan and Xiang-Gen Xia, “Block Coded Modulation for the Reduction of the Peak to Average Power Ratio in OFDM Systems”, Consumer Electronics, IEEE Trans. on Communication, Vol. 45, pp.1095-1099, Nov. 1999.
[4] G. Hill, M. Faulkner and J. Singh, “Cyclic Shifting and Time Inversion of Partial Transmit Sequences to Reduce the Peak-to-Average Power Ratio on OFDM”, Personal, Indoor and Mobile Radio Communication, Vol. 2, pp.18-21, Sept. 2000.
[5] C. Tellambura, “A Coding Technique for Reducing Peak-to-Average Power Ratio in OFDM”, in IEEE Global Telecommunication Conference, Vol. 5, Nov. 1998, pp.8-12.
[6] Nee, Richard van and Ramjee Prasad, OFDM for Wireless Multimedia Communication, Boston London, Artech House, 2000.
[7] European Telecommunication Standard, “Radio broadcast systems: digital audio broadcasting (DAB) to mobile, portable and fixed receivers,” ETSI final draft pr ETS 300 401, Nov. 1994.
[8] Agilent Technologies Application Note, “Characterizing Digitally Modulated Signal with CCDF Curves”, 2000.
[9] S. B. Weinstein and P. M. Ebert, “Data transmission by frequency division multiplexing using the discrete Fourier transform”, IEEE Trans. Comm. Technology, vol. COM-19, 50 No. 15, pp.628-634, Oct. 1971.
[10] Yiyan Wu and William Y. Zou, “Orthogonal Frequency Division Multiplexing: A Multi-Carrier Modulation Scheme”, IEEE Trans. on Consumer Electronics, Vol. 41, No. 3, pp.392-399, August 1995.
[11] William Y. Zou, Yiyan Wu, “COFDM: An Overview”, IEEE Trans. on Broadcasting, Vol. 41, No. 1, pp.1-8, March 1995.
[12] Yi Sun, “Bandwidth-Efficient Wireless OFDM”, IEEE Journal on Selected Areas in Communications, Vol. 19, No. 11, pp.2267-2278, November 2001.
[13] A. D. S. Jayalath, C. Tellambura and H. Wu, “Reduced Complexity PTS and New Phase Sequences for SLM to Reduce PAP of An OFDM Signal”, Vehicular Technology Conference Proceedings , TOKYO, Spring, 2000, pp.1914-1917.
[14] J. H. Scott, “The How and Why of COFDM”, EBU Technical Research, pp.1-2, Winter 1998.
[15] Y. Wu, et al., “OFDM for digital television terrestrial distribution over channels with multipath and non-linear distortion,” Proceeding of the Intl. conf. on HDTV 94, Turin Italy, Oct. 1994.
[16] Stefan H. Muller and Johannes B. Huber, “A Comparison of Peak Power Reduction Schemes for OFDM”, in Global Telecommunications Conference, GLOBECOM Nov. 1997, Vol. 1, pp.3- pp.8.
[17] J. A. C. Bingham, “Multicarrier modulation for data transmission: An idea whose time has come”, IEEE Comm. Mag., pp5-pp14, May 1990.
[18] E. F. Casas and C. Leung, “OFDM for data communication over mobile radio FM channels – part I: Analysis and experimental results”, IEEE Trans. Comm., vol. 39, pp.783-pp.793, May 1991.
[19] S. Verdu, “Wireless bandwidth in the making”, IEEE comm. Mag., vol. 38, pp.53-pp.58, 51 July 2000.
[20] Chintha Tellambura, “Improved Phase Factor Computation for the PAR Reduction of An OFDM Signal Using PTS”, IEEE Communication Letters, Vol. 5, No. 4, pp.135-137, April 2001.
[21] G. R. Hill, M. Faulkner and J. Singh, “Reducing the Peak-to-Average Power Ratio in OFDM by Cyclically Shifting Partial Transmit Sequences”, Electronics Letters, Vol.36, No.6, pp.560, March 2000.
[22] K. Sathananthan and C. Tellambura, “Partial Transmit Sequence and Selected Mapping Schemes to Reduce ICI in OFDM System”, in Global Telecommunications Conference, GLOBECOM, Dec. 2000, Vol. 1, pp.82- pp.86.
[23] A.D.S. Jayalath, and C. Tellambura, “The Use of Interleaving to Reduce the Peak-to-Average Power Ratio of An OFDM Signal”, IEEE, pp.82-86, 2000.
[24] Pauli, M., and H. P. Kuchenbecker, “Minimization of the Inter-modulation Distortion of a Nonlinearly Amplified OFDM Signal”,
Wireless Personal Communications, Vol. 4, N0. 1, pp.93-101, Jan. 1997.
[25]Wilkinson,T. A., and A. E. Jones, “Minimization of the Peak-to-Mean Envelope Power Ratio of Multicarrier Transmission Schemes by Block Coding”, Proceeding of IEEE Vehicular Technology Conference, Chicago, pp.825-829, July 1995.
[26] Kusha Raj Panta and Jean Armstrong, “Use of a Peak-to-Average Power Reduction Technique in HIPERLAN2 and its Performance in a Fading Channel”, Department of Electrical Engineering, La Trobe University, Bundoora, VIC 3086, Australia, pp.1-5.
[27] R. W. Bauml, R. F. H. Fischer, and J. B. Huber, “Reducing the peak-to-average power ratio of multicarrier modulation by selective mapping”, Electron. Lett., vol. 33, no. 5, pp.2056-2057, Oct. 1996.
[28] S. H. Muller and J. B. Huber, “OFDM with reduced peak-to-average power ratio by 52 optimum combination of partial transmit sequences”, Electron. Lett., vol. 33, no. 5, pp.368-369, Feb. 1997.
[29] LAN/MAN Standards Committee of the IEEE Computer Society, “Part 11: Wireless LA Medium Access Control(MAC) and Physical Layer(PHY) Specification: High-speed Physical Layer in the 5GHz Band”, Sept. 1999.
[30] De Wild, A., “The Peak-to-verage Power Ratio of OFDM”, M. Sc. Thesis, Delft University of Technology, Delft, The Netherlands, Sept. 1997.
[31] May, T., and H. Rohling, “Reducing the Peak-to-Average Power Ratio in OFDM Radio Transmission Systems”, Proceedings of IEEE VTC ’98, Ottawa, Canada, pp. 2774-2778, May, 1998.