臺灣博碩士論文加值系統

在本篇論文中，我們研究在正交分頻多工(Orthogonal Frequency Division Multiplexing, OFDM)系統下，使用選擇性映射(selected mapping, SLM)和削減法(Clipping)以及部分傳送序列(Partial Transmit Sequence, PTS)來降低高峰值對均值功率比(peak-to-average power ratio, PAPR)。傳統SLM方法降低PAPR的效能不錯，但實行的複雜度很高，我們研究幾種SLM架構使用低複雜度的轉換矩陣來取代IFFT 區塊，如此一來便可以有效降低系統計算複雜度。透過模擬結果我們發現低複雜度的SLM架構，其降低PAPR的能力比傳統SLM稍微差一點，而使用修正過的轉換向量之SLM架構，能達到和傳統SLM相同的位元錯誤率(bit error rate, BER)。相較於SLM架構，Clipping以及PTS的方法在BER和降低PAPR的效能表現雖然較不理想，但這兩種方法可以提供較低的計算複雜度。

In this thesis, we study the selected mapping (SLM) schemes, the clipping scheme and the partial transmit sequence (PTS) scheme to reduce the peak-to-average power ratio (PAPR) of the OFDM system. The conventional SLM scheme provides good performance (in the PAPR reduction), however, it requires high computational complexity. The studied SLM schemes use a kind of low-complexity conversion matrix to replace the IFFT block so that the computational complexity can be reduced. Simulations results show that the studied SLM schemes result in slightly worse performance (in the PAPR reduction) than the conventional SLM scheme, they even show that the SLM schemes with the modify conversion vectors have the same BER performance as the conventional SLM scheme. Compared to the SLM schemes, the clipping scheme and the PTS scheme do not have good performance (in BER or the PAPR reduction), but they can provide low computational complexity.

致謝.....I
摘要.....II
Abstract.....III
目錄.....IV
圖目錄.....VI
表目錄.....VIII
第一章 緒論.....1
1.1 前言.....1
1.2 研究目的與動機.....1
1.3 論文架構.....2
第二章 正交分頻多工系統介紹.....3
2.1 正交分頻多工系統原理.....3
2.2 反離散傅立葉轉換(IDFT)和離散傅立葉轉換(DFT).....5
2.3 保護區間與循環字首.....6
2.4 正交分頻多工系統的優缺點.....9
第三章 正交分頻多工之峰值對均值功率比.....10
3.1 簡介.....10
3.2 峰值對均值功率比介紹與分佈.....10
3.3 超取樣(Oversampling).....12
3.4 降低峰均功率比之方法簡介.....14
3.4.1 Clipping.....14
3.4.2 Selected Mapping.....15
第四章 使用SLM、PTS、 Clipping降低PAPR.....18
4.1 簡介.....18
4.2 低複雜度的SLM架構.....18
4.2.1 第一種低複雜度SLM架構.....18
4.2.2 第二種低複雜度SLM架構.....21
4.2.3 第三種低複雜度SLM架構.....24
4.2.4 第四種低複雜度SLM架構.....24
4.2.5 第五種低複雜度SLM架構.....30
4.3 Partial Transmit Sequence.....31
4.4 削減法(Clipping).....33
第五章 模擬結果與分析.....35
5.1 模擬一.....36
5.2 模擬二.....38
5.3 模擬三.....42
5.4 模擬四.....45
5.5 模擬五.....46
5.6 模擬六.....48
5.7 模擬七.....51
第六章 複雜度分析比較.....54
第七章 結論.....62
參考文獻.....63

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