正交分頻多工系統是高效率的無線網路的熱門技術，可利用離散快速傅利葉轉換跟反快速傅利葉轉換來達成此項技術。近十幾年來，此技術已應用在非常多的地方跟領域上，例如: 非對稱的數位用戶網路(ADSL)、數位音頻廣播(DAB)、數位視頻廣播(DVB)、WiMAX ( 802. 16)和 寬頻區域網路 802.11(a, b, g) 等等。
雖然OFDM有許多好處以至於應用廣泛，不過還是有一些缺點存在。其中一項就是它有高的尖峰平均功率比。擁有高的PAPR比對於功率放大器來說，會造成功率放大器需要過大的線性操作區，如此容易導致信號失真嚴重。所以針對此問題，現在已經有許多技術已經克服此項缺點。部份傳輸序列為其中一個方法，而且為公認效果不錯的方法之一。而部份傳輸序列的主要精神為利用固定有限的已知均勻相位集合，去調整不同載波之相位，已達成降低尖峰平均功率比的效果。不過部份傳輸序列有一些缺點，需要較高的複雜度，以及需要傳隱藏資訊給接受端以至於可還原原始的信號。近年來相關PTS的研究都針對PTS的缺點方面改進。
在此研究論文中，我們是提出不同於以往的相位集合來達到更好降低尖峰平均功率比的效果。在模擬的結果中，很明顯的可以看出在考慮
相同數目的相位集合之元素情況下，我們提出的非均勻的相位集合的模擬結果比舊的均勻相位集合好。

Orthogonal frequency division multiplex (OFDM) is a very effective technique for the wireless high-speed data transmission and robust for selective fading channel and inter-symbol interference (ISI). Recently, OFDM has been used widely in many kinds of communication transmission systems and method such as digital audio broadcasting (DAB), wireless local-area network (WLAN), IEEE 802.11, WiMAX (IEEE 802. 16) and Asymmetric Digital Subscriber Line (ADSL).

However, it has some drawbacks to improve. One serious disadvantage is high peak-to-average power ratio (PAPR). If the transmitted signal has high PAPR, the D/A converters and amplifiers need to have large dynamic range. Otherwise output signal will have serious distortion.

In recent years, many schemes are efficient to reduce PAPR. Although a lot of schemes can reduce PAPR efficiently, we only focus on PTS algorithm and have a modified one in this thesis. In the thesis, we propose a non-uniform phase set in PTS and show it has better performance than original phase set in PTS.

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