超寬頻(Ultra Wide-Band, UWB)系統對於時間的良好解析度，可應用在基於訊號抵達時間(Time of Arrival, TOA)或訊號抵達時間差(Time Difference of Arrival, TDOA)資訊的無線室內定位，使其有相當高的精準度。本論文主旨在研究多頻帶正交分頻多工(Multi-band OFDM)超寬頻系統的訊號抵達時間估測，於系統標準下提出有效並簡化的訊號抵達時間估測演算法，所使用的演算法是以廣義最大相似(Generalized Maximum Likelihood, GML)演算法為基本架構。
Multi-band OFDM系統藉由所傳送的時域同步序列進行訊號抵達時間估測，本文中依所使用的訊號特性對GML演算法其實現方式加以修改，將其應用於Multi-band OFDM系統中。由於GML演算法在實現時所需的運算時間較長，本文中並提出簡化的方法，降低演算法在實現時運算複雜度。由模擬結果可知，相較於互相關性(Cross Correlation)演算法與原本GML演算法的實現架構，所提出的改良型GML演算法可以有效減輕多重路徑干擾所造成的影響，增加系統在訊號抵達時間估測上的準確度。本文中並提出相關的臨界值設定與訊雜比估測方式，使改良型GML演算法在實際應用上更具可行性。

The fine time resolution of ultra wide-band (UWB) systems enables applications in TOA/TDOA based high precision wireless indoor location. The main purpose of this thesis is to investigate TOA estimation in multi-band OFDM UWB systems. We propose an effective and simplified TOA estimation algorithm for multi-band OFDM standard. The proposed algorithm is based on the generalized maximum-likelihood (GML) algorithm.
The TOA estimation algorithm utilizes the preamble signal in multi-band OFDM system. We modify the realization method of GML algorithm according to the preamble signal properties and apply it to multi-band OFDM system. From simulation results, by comparing with cross correlation algorithm and the original GML algorithm, the proposed algorithm has ability to mitigate multipath interference and improves TOA estimation accuracy. In this thesis we also discuss the thresholds setting and SNR estimation problems to make the proposed algorithm more realizable.

誌謝…………………………………………………………………i
中文摘要……………………………………………………………ii
英文摘要……………………………………………………………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 文獻探討與研究動機………………………………………………2
1.3 論文架構……………………………………………………………3
第二章 Multi-band OFDM系統簡介……………………………………4
2.1 系統標準簡介………………………………………………………4
2.1.1 操作頻帶頻率……………………………………………………4
2.1.2 通道化……………………………………………………………4
2.1.3 傳送訊號及訊框格式……………………………………………5
2.1.4 PLCP Preamble……………………………………………………7
2.1.5 發射機方塊圖……………………………………………………9
2.1.6 接收機方塊圖……………………………………………………9
2.2 距離量測與定位…………………………………………………10
2.2.1 雙向傳時………………………………………………………10
2.2.2 距離量測相關規定……………………………………………12
第三章 Multi-band OFDM系統之訊號抵達時間估測………………13
3.1 超寬頻通道模型…………………………………………………13
3.2 接收訊號表示……………………………………………………16
3.3 傳統訊號抵達時間估測方式……………………………………21
3.3.1 最強路徑決策法………………………………………………21
3.3.2 互相關性演算法………………………………………………22
3.4 適用於Multi-band OFDM系統之GML演算法……………………25
3.4.1 GML演算法……………………………………………………25
3.4.2 改良型GML演算法……………………………………………29
第四章 演算法臨界值分析…………………………………………32
4.1 通道統計特性與錯誤機率分析…………………………………33
4.1.1 通道統計特性…………………………………………………33
4.1.2 錯誤機率分析…………………………………………………37
4.1.3 電腦模擬與分析………………………………………………43
4.2 均方根誤差統計與臨界值決定…………………………………48
4.2.1 抵達時間估測演算法在實現時的考量………………………48
4.2.2 均方根誤差統計與臨界值決定………………………………50
4.2.3 電腦模擬與分析………………………………………………50
4.3 雜訊功率計算……………………………………………………56
第五章 結論與建議……………………………………………………61
附錄 A…………………………………………………………………63
參考文獻………………………………………………………………69

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