本篇論文主旨在研究低速率無線個人區域網路系統之訊號抵達時間估測。在稠密的多重路徑環境裡，估測接收訊號的第一個抵達路徑所使用的估測演算法是以廣義最大概似(Generalized Maximum Likelihood, GML)演算法為主體，但GML演算法的運算需要很久的時間，有時甚至無法實現，勢必需要簡化架構，以遞迴的形式進行搜尋。設定兩臨界值參數做為演算法的停止機制，其中一個為搜尋路徑的抵達時間，另一個為搜尋路徑的衰減振幅。關於臨界值設定上，首先使用最小錯誤機率法，它利用誤判(false alarm)機率與遺失(miss)機率相加總合最小為原則來設定臨界值。在改善臨界值設定上的問題，利用均方根誤差統計法來實現，此改善方法將兩個臨界值在一個合適的範圍內變動，並計算每一次變動的均方根誤差值，再選擇最小均方根誤差所對應的臨界值做為演算法所需的臨界值。均方根誤差在模擬中所造成的非線性現象，將由結合模擬退火法的技術來改良，利用模擬退火法於非線性環境中良好的求解過程，解決每次須重新計算區域內每一個解後再找尋最佳解的問題。模擬結果顯示，當訊雜比在大於或等於4 dB後，提出的改善方式，相較於均方根誤差統計法，會有較佳的結果表現。

The main purpose of this thesis is to estimate the signal arrival time in low rate wireless personal area network systems. In a dense multipath environment, the generalized maximum-likelihood (GML) algorithm can be used for the time-of-arrival (TOA) estimation. Nevertheless, the GML algorithm is very time-consuming and usually takes a long period of time, and sometimes fails to converge. Hence, a simplified scheme that would improve the algorithm is investigated. In the simplified scheme, the search is executed in a sequential form. Two threshold parameters are determined for the stop condition in the algorithm. One threshold is on the arrival time of estimated path, while the other is on the fading amplitude of estimated path. The determination of thresholds can be based on the minimum error probability, which is defined as the sum of the false alarm probability and the missing probability. Root-mean-square error statistics are used to improve the thresholds setting. In this scheme, candidate pairs of thresholds are evaluated in each appropriate range. To solve the problem that the root-mean-square error value for each pair of thresholds is calculated, the simulated annealing is adopted for searching the best threshold pair. The problem that all possible solutions in a large range must be evaluated can be solved by simulated annealing. From the simulation results, it is seen that, while the signal-to-noise ratio is larger or equal to 4dB, the proposed scheme can achieve better performance than the root-mean-square error statistics scheme.

誌謝 i
中文摘要 ii
英文摘要 iii
目錄 iv
圖目錄 vi
表目錄 ix
第一章 緒論 1
1.1 前言 1
1.2 文獻探討及研究動機 1
1.3 論文架構 3
第二章 訊號抵達時間估測法及臨界值設定 4
2.1 室內環境之距離量測及定位 4
2.1.1 測距與定位觀念概述 4
2.1.2 雙向測距 5
2.2 訊號描述 7
2.2.1 訊號描述整理 7
2.2.2 IEEE802.15.4訊號之描述 10
2.3 訊號抵達時間估測法 15
2.3.1 互相關性演算法(Cross Correlation Algorithm) 15
2.3.2 廣義最大概似演算法(GML Algorithm) [12] 17
2.3.3 改良式廣義最大概似演算法(Modified GML Algorithm) [29] 21
第三章 臨界值設定及模擬退火法 24
3.1 最小錯誤機率法 24
3.1.1 通道統計特性 24
3.1.2 錯誤機率分析 26
3.2 均方根誤差統計法 29
3.3 模擬退火法 30
3.3.1 背景及原理介紹 30
3.3.2 適用於臨界值設定之退火流程 36
第四章 電腦模擬及分析 39
4.1 通道統計特性分析 39
4.2 最小錯誤機率法 42
4.3 均方根誤差統計法 54
4.4 模擬退火法於臨界值設定 62
4.5 訊雜比估測 65
第五章 結論及建議 69
附錄A 無線個人區域網路系統之簡介 71
A.1 無線個人區域網路 71
A.2 IEEE 802.15.4特色 71
A.2.1 低成本及低功率 71
A.2.2 操作頻帶及資料速率 72
A.3 IEEE 802.15.4a通道模型 73
參考文獻 81

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