正交分頻多工系統對於時間與頻率的誤差相當的敏感，因此已有許多方法被提出來解決這兩個問題。在本論文裡，我們提出了一個應用在此系統中的時間偏差估測方法，此方法是在傳送端的時域上傳送一組特定的訓練符元，在接收端則依據所定義的時間準則來估測時間偏移。這個方法與Zhongshan Zhang的方法相較下不但不會受到頻率偏差的影響，因此可以降低估測時間時所需的複雜度；同時與傳統Schmidl以及Minn的方法相較下在估測時間上會有更高的準確性。在本論文中我們另外會對這一組新訓練符元所定義的時間準則做在正確時間點時的統計特性分析，即分析其期望值與變異數，根據分析與實際模擬的結果，可以驗證分析的正確性。最後由電腦模擬結果更可以證明我們提出的方法在估測時間上有較好的效能。

Orthogonal frequency division multiplexing systems are much more sensitive to timing and frequency error, therefore there were several methods to estimate time and frequency offset. In the thesis, a novel timing offset estimation method for OFDM systems is proposed, it transmits a specific training symbol in the time domain at transmitter. At the receiver, it estimate the timing offset by using a specific timing metric. The proposed scheme isn’t affected by the frequency offset compare with Zhang’s method, and it can estimate timing offset more accurately than Schmidl’s method and Minn’s method. We will analyze the statistical characteristic of the timing metric we proposed at correct time. According to the analysis and simulation result, it can show the accuracy of our analysis. Finally from the simulation result, it demonstrates that the proposed scheme has better performance.

中文摘要...I
Abstract...II
目錄...III
圖目錄...IV
第一章 導論...1
1.1 研究動機...1
1.2論文章節介紹...2

第二章 正交分頻多工系統簡介...3
2.1 單載波與多載波系統介紹...3
2.2 傳統的正交分頻多工系統架構...4
2.3 利用離散傅立葉轉換的正交分頻多工架構...7
2.4 保護區間與循環字首...9
2.5 正交分頻多工系統的優缺點...11

第三章 正交分頻多工系統中現有時間同步方法介紹...14
3.1 同步概念簡介...14
3.2 Schmidl's訓練符元時間同步方法...15
3.3 Minn's訓練符元時間同步方法...18
3.4 Zhongshan Zhang's訓練符元時間同步方法...21

第四章 新的訓練符元架構介紹與分析...25
4.1 Zhongshan Zhang's時間準則與頻率誤差關係推導...25
4.2 新訓練符元架構...26
4.3 新方法的時間準則與頻率誤差關係推導...28
4.4 時間準則在正確時間點的統計特性分析...30

第五章 模擬結果與討論...36
第六章 結論...43
參考文獻...44

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