臺灣博碩士論文加值系統

正交分頻多工系統是一項非常熱門的傳輸技術，但是通常系統的峰均比會很大。在這篇論文裡，我們提出一個低複雜度降低峰值的技術。設計的方法是藉由選出一些子載波分別乘上旋轉因子來達到降低峰值的目標。我們將會用模擬結果來說明所提出的方法能夠有效地降低峰值且複雜度很低。

Recently there has been great interest in the Orthogonal Frequency Division Multiplexing (OFDM) systems. However one disadvantage of OFDM systems is high peak-to-average power ratio (PAPR). In this thesis, we will propose a new method called Subchannel Peak Reduction (SPR). The symbols of a few selected subchannels are chosen to multiple a rotation individually so that PAPR is reduced. Transmission rate is slightly lower. However, no side information bit is needed. The optimal solution of the rotation can be found by exhaustive search (SPR-ES).We will propose an iterative ap-
proach method (SPR-IT) to tnd suboptimal rotating for the selected subchannels. SPR-IT can have lower complexity than SPR-ES. Simulation results shows SPR-ES and SPR-IT can e±ciently reduce the peak value of the transmitted signal. The simulations will demonstrate that our method provide a nice tradeoff between bit rate and PAPR reduction.

1 Introduction --1
1.1 Outline --3
1.2 Notations --4
2 OFDM systems --5
2.1 The OFDM systems model --5
2.2 The PAPR of OFDM systems --6
3 PAPR Reduction By Tone Injection [6] --9
3.1 Tone Injection for Real Multicarrier Systems --9
3.2 Tone Injection for passband communications --15
4 The Subchannel Peak Reduction Method --19
4.1 An Exhaustive Search Scheme --20
4.2 An Iterative Approach Method --25
5 Computational Complexity --30
5.1 Exhaustive Search --30
5.2 Iterative Approach --34
5.3 Tone Injection (for passband communication) --35
6 Simulation Results --39
7 Conclusion --46

[1] J. A. C. Bingham, "Multicarrier Modulation For Data Transmission: An Idea Whose Time Has Come," IEEE Commun. Mag, vol. 28, no. 5, May 1990, pp. 5-14.
[2] M. Aldinger, "Multicarrier COFDM scheme in high bit rate ratio local area network," in Proc. 5th IEEE Int. Symp. Personal, Indoor and Mobile Radio Communications, The Haugue, The Netherlands, Sept. 1994, pp. 969-973.
[3] ETSI, "Digital Video Broadcasting; Framing, Structure, Channel Coding and Modulation for Digital Terrestrial Television (DVB-T)," ETS 300 744,1997.
[4] ETSI, "Digital Audio Broadcasting (DAB) to Mobile, Protable and Fixed Receivers," ETS 300 401, 1994.
[5] A. Ruiz, John M. Cio±, and S. kasturia, Discrete Multiple Tone Modulation with Coset Coding for The Spectrally Shaped Channel, IEEE Transcation on Communications, Vol. 40, No. 6, Page (s) : 1012-1029, June 1992.
[6] J. Tellado, Multicarrier Modulation with Low PAR: Applications to DSL and Wireless Kluwer Acdamic, Press. 2000.
[7] R. O'Nell and L. B. Lopes, "Envelope Variations and Spectral Splatter in Clipped Multicarrier Signals," Proc. IEEE PIMRC '95, Toronto, Canada, Sept. 1995, pp. 71-75.
[8] A. E. Jones, T. A. Wilkinson, and S. K. Barton,"Block Coding Scheme for Reduction of Peak to Mean Envelope Power Ratio of Multicarrier Transmission Scheme," Elect, Lett, vol. 30, no. 22, Dec. 1994, pp. 2098-99.
[9] J. A. Davis, and J. Jedweb,"Peak-to-Mean Power Control in OFDM, Golay Complementary Sequences, and Reed-Muller Codes" IEEE, Trans Info.Theory, vol. 45, no. 7, Nov. 1999, pp. 2397-17.
[10] K. G. Paterson and V. Tarokh,"On the Existence and Construction of Good
Codes with Low Peak-to-Average Power Ratios," IEEE, Trans Info. Theory, vol. 45, no. 6, Sept. 2002, pp. 1974-87.
[11] R. W. BÄauml, R. F. H. Fisher, and J. B. Huber, Reducting the Peak-to-Average Power Ratio of Multicarrier Modulation by Selected Mapping ," Elect, Lett, vol. 32, no. 22, Oct. 1996, pp. 2056-57.
[12] P. Van Eelvelt, G. Wade, and M. Tomlinson, Peak to average power reduction for OFDM schemes be selective scrambing.Elect, Lett,, vol. 32, no. 21,pp. 1963-1964, Oct. 1996.
[13] S. H. MÄuller and J. B. Huber, OFDM with Reduced Peak-to-Average Power Ratio by Optimum Combination of Partial Transmit Sequences,Elect, Lett, vol. 33, no. 5, Feb. 1997, pp. 368-69.
[14] C.-L. Wang, M.-Y. Hsu, and Y. Ouyang, A low-complexity peak-to-average power ratio reduction technique for OFDM systems, in Proc. 2003 IEEE Global Telecommun. Conf. (GLOBECOM 2003), San Francisco, CA, Dec.
2003, pp. 2375-2379.
[15] C.-L. Wang and Y. Ouyang,Low-Complexity Selected Mapping Schemes for Peak-to-Average Power Ratio Reduction in OFDM Systems, IEEE Transca-
tion on Communications, Vol. 53, no. 12, Dec. 2005.
[16] S. H. Han and J. H. Lee, PAPR Reduction of OFDM Signals Using a Reduced
Complexity PTS Technique, IEEE Sig. Proc. Lett., vol. 11, no. 11, Nov. 2004,pp. 887V90.