正交分頻多工(OFDM)對於無線高資料傳輸來說是一種非常吸引人的技術。然而，可能產生高的均峰值(PAPR)卻限制了其實際實作的應用。一個高的均峰值在類比對數位的轉換和數位對類比的轉換上的複雜度，以及射頻功率放大器上的使用效率，增加了許多不利的條件。

在此篇論文中，回顧一些主要降低均峰值的方法。以分布傳送序列(PTS)可以在無非線性失真的情況下降低均峰值似乎是種作用大且效率高的方法，但是增加了在計算上的複雜度。此外，使用一種簡單而有效的壓展法來降低均峰值，但是雜訊放大的問題蠻嚴重地。當使用一個門檻去停止分布傳送序列的運算且結合壓展法通過非線性通道的環境下，其性能的表現會比僅使用舊有的分布傳送序列或壓展法來的好。我們使用SPW模擬展現均峰值的下降效果、最佳後退輸出點(OBO)，以及通過非線性通道錯誤率的分析。

Orthogonal Frequency Division Multiplexing (OFDM) is a very appealing technique for achieving high-rate wireless data transmission. However, the potentially high Peak-to-Average Power Ratio (PAPR) in OFDM has limited its applications for practical implementations. A high PAPR brings disadvantages like an increased complexity of the A/D and D/A converters and a reduced efficiency of the RF power amplifier.
In this thesis, some main PAPR reduction methods are reviewed. Partial transmit sequence (PTS) seems to be powerful and efficient method known to reduce OFDM peak power without nonlinear distortion, but the computational complexity has been increased. Moreover, a simple but effective companding technique to reduce the PAPR of OFDM is proposed, but the problem of amplifying the noise is serious. When a PAPR threshold is applied to stop computations in PTS that is combined with a companding method, this way performs better performance through a nonlinear channel than just using conventional PTS or companding methods. The simulation results obtained by SPW including the reduction of the PAPR, the optimal output backoff (OBO), and BER performance through a nonlinear channel are presented.

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