本篇論文提出了一個迭代式的符號預先失真方法來達到降低正交分頻多工系統內的高峰質對平均功率比( peak-to-average power ratio，簡稱PAPR )。在所提出的方法當中，我們會利用制定出的公制去計算頻率域上每個輸入資料點實部及虛部對於時間域上那些具有高量質取樣點的貢獻度，對於頻率域上輸入資料點貢獻度較多者進行符號的預先失真，並且分別對其作加權。不同於之前所提出過的方法，加權函數的選擇不需要根據不同的正交分頻多工系統事先設定。所提出的方法也不需要傳送額外訊息給接收端，所以在接收端也不需要額外的負載來做訊息偵測。另外，透過在每一次迭代控制截波臨界值以及收斂因子，此演算法在低截波臨界值時能夠達到近乎相同的峰質對平均功率比。

This thesis proposes an iterative symbol predistortion scheme for peak-to-average power ratio reduction in OFDM systems. In the proposed scheme, the real and/or the imaginary parts of a set of input symbols in the frequency domain are expanded by using a metric for evaluating their contribution to the time-domain peak samples. The real and imaginary parts of the frequency-domain symbols with the largest metrics are selected for expanding by weighting them separately. Different from a previous related work, the weighting functions have less parameters that have to be predetermined according to different OFDM systems. The proposed scheme does not need to transmit any side information to the receiver and there is no additional loading for data detection at the receiver. In addition, by adopting clipping level control during each iteration, the proposed scheme can achieve almost the same PAPR reductions for severely low initial clipping levels.

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