為了改善在多載波系統上，高峰均值功率比(Peak-to-Average Power Ratio, PAPR)的缺點，本論文藉由結合兩種傳統方法，分別是各個使用者之展頻碼(Spreading Code)組合以及子載波擾頻(Subcarrier Scrambling)，以推導出一組統計特性近似的時域訊號功率變異數度量式(Metric)，利用不同的展頻碼組合對PAPR影響以及擾亂子載波極性，在多載波分碼多重接取(Multi-Carrier Code Division Multiple Access, MC-CDMA)系統上對於PAPR之降低得到明顯的效果。由於詳盡搜尋(Exhaustive Search)之計算數量太大，因此我們利用一低複雜度之代換搜尋法(Replacement Search Method, RSM)來降低搜尋運算次數，得到相當不錯之結果，並且可以藉由更進一步的增加疊代次數，來使得PAPR之降低效能更加明顯。

In order to improve the drawback of the high peak-to-average power ratio (PAPR) on the multi-carrier systems, in this paper we derive a statistical characterization approach of the time domain signal power variance metric by means of every user’s spreading code combination and subcarrier scrambling. We obviously reduce the PAPR on the multi-carrier code division multiple access (MC-CDMA) systems by resorting the combination of spreading codes and scrambling the polarities of subcarriers. Due to the large calculative number of exhaustive search, we use a low complexity Replacement Search Method (RSM) to reduce the calculation times of searching, and obtain a good result. Moreover, we can get a better PAPR reduction performance by increasing the number of iteration.

論文審定書 i
誌謝 ii
論文摘要 iii
Abstract iv
目錄 v
圖目錄 vii
表目錄 viii
第一章 導論 1
1.1 研究背景 1
1.2 研究動機 1
1.3 論文架構 3
第二章 系統架構 4
2.1 正交分頻多工系統 4
2.2 多載波分碼多重接取系統 6
2.3 峰均值功率比 8
2.4 Walsh-Hadamard正交展頻碼 10
第三章 傳統MC-CDMA之PAPR降低方法 12
3.1 訊號模型 12
3.2 訊號PAPR分析推導與搜尋法介紹 13
3.3 複雜度分析 16
第四章 提出之度量式推導與搜尋方法 18
4.1 訊號功率分析 18
4.2 訊號功率變異數度量式 20
4.3 低複雜度之搜尋法 27
4.4 複雜度分析 30
第五章 模擬結果 32
5.1 降低PAPR效能比較 32
5.2 TSM與RSM之複雜度比較 35
第六章 結論 38
參考文獻 39
中英對照表 44
縮寫對照表 48

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