臺灣博碩士論文加值系統

在傳統的正交分頻多工系統中，傳送訊號有著高峰值對均值功率比(Peak-to-Average Power Ratio, PAPR)的缺點。因此傳送訊號在經過功率放大器(Power Amplifier, PA)後容易進入飽和區，產生非線性失真並降低功率放大器的效能。在本篇論文中，我們針對利用疊加方式(superimposing scheme)傳送領航訊號對正交分頻多工系統中峰值對均值功率比的影響進行探討。在功率放大器直流功率固定的情況下，我們首先分析領航訊號與資料訊號的功率分配和傳送訊號峰值對均值功率比的關係。接著在考慮功率放大器的功率效益下，我們分析峰值對均值功率比和傳送資料訊號功率之間的關係。我們更進一步推導出使傳送資料訊號功率達到最大值的領航訊號及資料訊號功率分配的數學表示式。最後，我們將其適當的簡化得到一個封閉式(closed form)，在給定子載波數目和峰值對均值功率比門檻機率的條件下，能夠快速的得到領航訊號及資料訊號的最佳功率分配以使得傳送資料訊號的功率達到最大值。

In this thesis, the superimposed training scheme is applied to the orthogonal frequency division multiplexing (OFDM) systems. To optimize power amplifier efficiency, the optimal value of pilot power allocation is derived to maximize data power. Peak-to-average power ratio (PAPR) is one of the major drawbacks for OFDM systems. A large PAPR will push the power amplifier into the saturation area, leading to nonlinear distortion, and reduce power efficiency. By using the superimposed training schemes, the system can not only improve the bandwidth efficiency, but also reduce the PAPR. In this thesis, the relation between PAPR and power efficiency is analyzed. In addition, the close form formula is derived for determining the pilot power allocation so that data power is maximized.

中文摘要 I
ABSTRACT II
圖目錄 V
表目錄 VII
第一章 導論 1
1.1 研究動機 1
1.2 章節介紹 2
第二章 訊號模型 3
2.1 OFDM系統介紹 3
2.1.1 傳統分頻多工系統與正交分頻多工架構 4
2.1.2 PAPR介紹 10
2.2 OFDM系統下疊加序列傳輸介紹 11
2.2.1週期性脈衝領航訊號序列下的PAPR 11
2.2.2等振幅領航訊號序列下的PAPR 12
第三章 資料功率最佳化下領航訊號功率分配 14
3.1 功率放大器之功率轉換效率與PAPR的關係 14
3.2 資料功率最佳化的領航訊號功率比例分析 17
第四章 模擬結果與討論 26
4.1 PAPR的改善 26
4.2 資料功率模擬 29
第五章 結論與未來工作 35
附錄 A 37
參考文獻 38

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