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標題: 研究多重傳輸速率之正交分頻-分碼多工系統及其各項降低峰均值方法比較
Study and Comparison of PAPR Reduction Algorithm for Multi-Rate OFDM CDMA System
作者: 劉奇泳
Liu, Chi-Yung
關鍵字: 正交可變展頻係數;OVSF;峰均值比;PAPR
出版社: 電機工程學系所
引用: [1] R. V. Nee and R. Prasad, OFDM for Wireless Multimedia Communications, Artech House, Boston, 2000 [2] L.J. Cinimi. Jr. “Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing” IEEE Trans. Communication, vol. Com-33, pp.665-675, July -1985. [3] S.Hara and R.Prasad, “Overview of Multicarrier CDMA,” IEEE Communication Mag.,vol.35, no.12, pp126-133, Dec. 1997 [4] H. Ochiai and H. Imai, “OFDM-CDMA with peak power reduction based on the spreading sequences,” in Proc. ICC'98, vol.3, pp.1299-1303, June 1998. [5] M. Dell'Amico, M. L. Merani, and F. Maffioli, “Efficient Algorithms for the Assignment of OVSF Codes in Wideband CDMA,” IEEE International Conference, Communication, vol.5, pp.3055-3060, April-2 May 2002. [6] Y. S. Chen, and T. L. Lin, “Code Placement and Replacement Schemes for WCDMA Rotated-OVSF Code Tree Management,” IEEE Trans. on Mobile Computing, vol.5, no.3, March 2006. [7] T. Minn and K. Y. Siu, “Dynamic Assignment of Orthogonal Variable Spreading Factor Codes in W-CDMA,” IEEE Journal on Selected Areas in Communication, vol.18, no.8, August 2000. [8] S. Roman, Coding and Information Theory, Springer-Verlag, New York 1992. [9] J. Adamek, Fundation of Coding : Theory and Applications of Error-Correcting Codes, with an Introduction to Cryptography and Information Theory, John Wiley & Sons, Inc., Chichester, 1991 [10] F.J. MacWilliams and N. J. A. Sloane, The Theory of Error-Correcting Codes Amsterdam, The Nethwelands : North-Hollans, 1986. [11] M. F. Madkour and S. C. Gupta, “Multi-rate Multi-code CDMA Using FWT for Mobile and Personal Communications,” IEEE International Symposium, Personal, Indoor and Mobile Radio Communication, vol.2, pp.779-783 Sep.1998. [12] K.Sathananthan and C. Tellambura, “Peak-to-Average Power Ratio Analysis in Multicode CDMA,” IEEE Vehicular Technology Conference, vol1, pp.500-504, Sep. 2002. [13] O. Takyut, T. Ohtsukit and M. Nakagawat, “Orthogonal Variable Spreading Factor Code Selection for Peak Power Reduction in Multi-Rate OFCDM Systems,” IEEE Vehicular Technology Conference vol.1, pp.117-121, April 2003 [14] S. H. HAN and J. H. LEE, “An overview of peak-to-average power ratio reduction techniques for multicarrier transmission,” IEEE Wireless Communication , vol.12, pp.56-65, April 2005 [15] Li. Xiaodong and L. J. Cimini, “Effect of Clipping and filtering on the performance of OFDM,” IEEE Communication Lett., vol.2, pp.131-133, May 1998. [16] R. V. Nee and A. D. Wild, “Reducing the peak-to-average power ratio of OFDM,” IEEE Vehicular Technology Conference vol.3, pp.2072-2076 May 1998. [17] Lei Wang, Kyongkuk Cho, Dongweon Yoon and Sang Kyu Park, “A Recoverable Peak Cancellation Technique for PAPR Reduction of OFDM Signals,” IEEE Communication, Circuit and Systems Proceeding, vol.2, pp.1124-1127, June 2006. [18] A. E. Jones, T. A. Wilkinson and S. K. Barton, “Block coding scheme for reduction of peak to mean envelop power ratio of multicarrier transmission schemes,” IEEE Electron. Lett., vol.30, pp.2098-2099, Dec.1994. [19] F. Pingyi and X. Xiang-Gen, “Block coded modulation for the reduction of the peak to average power ratio in OFDM system,” IEEE Trans. Consumer Electron., vol.45, pp.1025-1029, Nov.1999. [20] S. H. Muller and J. B. Huber, “OFDM with reduced peak-to average power ratio by optimum combination of partial transmit sequence,” IEEE Electron. Lett., vol.33, pp.368-369, Feb. 1997. [21] A. Latif and N. D. Gohar, “Reducing peak-to-average power ratio (PAPR) using partial transmit sequence in OFDM systems” IEEE Conference, pp.126-130, Dec. 2003. [22] Somchai Jitapunkul, Krittee Wutthipompong, Jirapa Songthanasak and Suwich Kunaruttanapruk, “Peak to Average Power Ratio Reduction in MC-CDMA using Partial Transmit Sequences,” IEEE Wireless Telecommunication Symposium, pp.3-8, May 2004. [23] N. Ohkubo and T. Ohtsuki, “A Peak to Average Power Ratio Reduction of Multicarrier CDMA Using Selected Mapping,” IEEE Vehicular Technology Conference, vol.4, pp.2086-2090, Sep. 2002. [24] H. Breling, S. H. Muller-Weinfurtner and J. B. Huber, “SLM peak-power reduction without explicit side information,” IEEE Communication Lett., vol5, pp.239-241, June 2001.
為了滿足現今網路所提供的不同的服務項目,我們希望能夠提供多種的傳送速率,Multi-rate OFDM-CDMA就成了我們的首要選擇。我們使用OVSF碼作為展頻碼,將使用者區分成高傳送速率使用者(High Rate User , HRU)及低傳送速率使用者(Low Rate User , LRU)。因為Multi-rate OFDM-CDMA是以OFDM作為系統的基本架構,所以也和OFDM系統一樣,傳送訊號會有高PAPR值的缺點。過高的PAPR值會讓類比對數位轉換器的複雜度增加,容易受無線通訊系統傳輸端的功率放大器非性扭取失真的影響,而嚴重降低傳送訊的品質。所以需要有大的動態範圍的線性放大器,才能保證接收到所有PAPR值較大的訊號,而不會有訊號因超過其接收端放大器動態範圍被截的現象。
在本論文中,我們將介紹了Multi-rate OFDM-CDMA的整體架構,定義系統傳送訊號的PAPR值,並找出產生最小PAPR值的OVSF碼組合,可讓不同的使用者組合情況下,都保證有較小的PAPR值。同時也介紹降低PAPR值的方法,如部分傳送序列(Partial Transmit Sequence , PTS )及選擇性映射(Selective Mapping , SLM)。在部分傳送序列中使用不同畫分次區塊的方式,以及畫分次區塊的數目來比較所降低的PAPR的效能。在選擇性映射中使用不同種類及不同數目的擾亂序列來降低PAPR。模擬的結果顯示在Multi-rate OFDM-CDMA系統中,使用部分傳送序列及選擇性映射來降低PAPR值都有不錯的效果。

The OFDM-CDMA system is a combination of the Orthogonal Frequency Division Multiplexing(OFDM) and Code Division Multiple Access(CDMA) and thus has robust resistance against frequency-selective fading. Other advantages of OFDM-CDMA are the high transmission rate and high efficiency use in spectrum. Furthermore, the OFDM-CDMA system provides high capacity for the system service.
The future transmission systems are expected to support multi-rate signal ; thus the multi-rate OFDM-CDMA system has become the most suitable choice. The principle of multi-rate OFDM-CDMA is to divide the active users into the high rate users and the low rate users by orthogonal variable spreading factor (OVSF) code. However, the transmitted signals of multi-rate OFDM-CDMA and OFDM have the same drawback, the high peak-to-average power ratio (PAPR). High PAPR results in raising the complexity of A/D converters and prohibits its applications widely.
In this thesis, the author provides an overview of multi-rate OFDM-CDMA systems and reviews the definition of PAPR, partition transmit sequence(PTS), and selective mapping(SLM). In addition, the author also uses the techniques of partitions of partition transmit sequence(PTS) and selective mapping(SLM) to improve the PAPR performance in a multi-rate OFDM-CDMA systems. Simulation results show that the PAPR performance of multi-rate OFDM-CDMA systems with variety of combinations of spreading sequences can be improved by using the PTS and the SLM algorithm.
其他識別: U0005-2307200715003900
Appears in Collections:電機工程學系所

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