超寬頻 (Ultra-wideband, UWB) 技術不僅讓不同的系統能共存於相同頻帶，更提供低成本且高速度的短距離無線傳輸服務。由於超寬頻訊號的極大頻寬和極佳的時間解析度，此訊號具有對抗多重路徑通道衰退之特性。此外，如正交分頻多工 (Orthogonal Frequency Division Multiplexing, OFDM) 系統因具備簡單的通道等化以及高頻譜效益之優勢，已被建議使用於超寬頻通訊上。
在本論文中，我們將於IEEE 802.15.3a超寬頻通道模型下精確分析正交分頻多工系統中不同子載波頻率響應的相關性，並利用超寬頻訊號的特性簡化分析結果，進一步減少所需的計算量。接著根據精確的分析，我們計算描述同調頻寬 (Coherence Bandwidth) 和延遲擴展 (Delay Spread) 關係之參數。最後，透過所求得參數的線性回歸分析，我們提出了經過改善後的關係參數。這些修正後的參數會和先前研究量測出的參數相互比較，其結果顯示我們所提出的修正能更準確的描述時域及頻域通道特性轉換之關係。

Ultra-wideband (UWB) is a technology that can coexist with other systems and provide low-cost and high-speed indoor wireless services. Owing to its extremely wide bandwidth and high time resolution, multipath fading resistance and high-speed transmission are the main characteristics of UWB technology. In addition, schemes such as orthogonal frequency division multiplexing (OFDM) have been proposed for UWB systems due to the remarkable properties including simpler channel equalization and high spectral efficiency.
In this thesis, we perform a comprehensive study of correlation analysis for UWB-OFDM systems. First, precise evaluation of the correlations for OFDM systems over IEEE 802.15.3a channel structure is conducted. Simplified formulas are also provided to ease the computation burden. Subsequently, relation parameters in the relationship between coherence bandwidth and delay spread are determined with the aid of analytical results. Finally, linear regression is employed to provide improved relation parameters, which are compared with results of previous research to show the effectiveness of capturing time-frequency-domain characteristics.

Abstract i
Contents ii
Chapter 1 Introduction 1
Chapter 2 IEEE UWB Channel Model and Exact Channel Statistics 4
Chapter 3 Correlation Coefficient Analysis on OFDM Systems 14
Chapter 4 Numerical and Simulation Results 31
Chapter 5 Conclusion 52

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