臺灣博碩士論文加值系統

隨著無線通訊技術及其服務需求功能的迅速發展, 使得無線行動定位技術廣泛受到重視。而無線定位系統中, 無可避免訊號受非視線(Non-Line-of-Sight, NLOS) 傳播影響, 導致定位精確度嚴重降低。因此本篇論文提出混合型TOA/AOA(Time of Arrival/ Angle of Arrival) 之非視線傳播鑑別與無線定位演算法,解決NLOS 造成的定位誤差。此演算法主要功能為判別多少個量測訊號為直視傳播(Line-of-Sight, LOS)並同時鑑別出, 其鑑別原理為透過多個基地台所量測的訊號抵達時間(TOA) 與訊號抵達角度(AOA) 參數之蒐集, 利用殘餘資訊的概念去判別量測值中是否含有NLOS誤差, 再針對被鑑別出之直視傳播量測值做位置估測, 有效去除NLOS 誤差, 提升定位精確度。
從電腦模擬結果顯示, 單純TOA 量測資訊之定位系統架構僅能鑑別到LOS 基地台最少有三個的情形, 並且在LOS 基地台個數大於三時有高鑑別率, 但在LOS 基地台個數為三時, 鑑別能力明顯下降, 導致定位誤差變大; 而使用TOA 與AOA 量測資訊結合時, 由於AOA 定位法僅需兩個量測值即能定位的特性, 使得此演算法能鑑別到LOS 基地台最少兩個的情形, 並即使在LOS 基地台為兩個時, 仍保有高的NLOS鑑別能力, 使其定位效能顯著提升。

With the rapid development of wireless networking technology and the great growth of service demand, accurate wireless location estimation has gained considerable attention. Most wireless location system may suffer from non-line-of-sight (NLOS) propagation error, which leads to a severe degradation of position accuracy. In this thesis, we propose a hybrid TOA/AOA (time of arrival/ angle of arrival) non-line-of-sight identification and wireless location technology to cope with NLOS condition. This algorithm can simultaneously determine the number of line-of-sight (LOS) base stations (BSs) and identify them. The identification part is to collect all TOA and AOA parameters from all BSs and to use residual information to detetmine whether the NLOS error is present in measurements. The localization method only processes the LOS measurements to avoid the NLOS error and increases position accurary.
The simulation results show that the location system with TOA measurements can identify three or more LOS-BSs. The system has a high identification accuracy when the number of LOS-BSs is more than three. When the number of LOS-BSs is three, the degraded identification capability leads to larger position errors. When the AOA information is available in the positioning system, the TOA is combined with AOA because the property of the AOA localization method which needs only two measurements to locate the MS makes the location system capable of identifying two LOS-BSs. When the number of LOS-BSs is two, the combination of TOA and AOA measurements maintains a higher NLOS identification accuracy and make its location performance remarkably promoted.

1 緒論1
1.1 研究背景. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2 研究動機. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1.3 論文結構. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 無線定位法與定位誤差來源4
2.1 無線定位原理. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.1.1 訊號抵達時間定位法. . . . . . . . . . . . . . . . . . . . . . 5
2.1.2 訊號抵達角度定位法. . . . . . . . . . . . . . . . . . . . . . 7
2.1.3 混合型定位法. . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 影響定位準確性因素來源. . . . . . . . . . . . . . . . . . . . . . . 9
2.2.1 多重路徑傳播效應. . . . . . . . . . . . . . . . . . . . . . . 9
2.2.2 非視線傳播(NLOS) 效應. . . . . . . . . . . . . . . . . . . 10
3 鑑別NLOS 誤差之定位系統12
3.1 鑑別NLOS 誤差之定位系統架構. . . . . . . . . . . . . . . . . . . 12
3.1.1 TOA鑑別NLOS 誤差之定位系統功能流程. . . . . . . . . . 12
3.1.2 改良型TOA 鑑別NLOS 誤差之定位系統功能流程. . . . . 14
3.1.3 混合型TOA/AOA 鑑別NLOS 誤差之定位系統功能流程. . 15
3.2 訊號參數模型. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.1 時間之參數模型. . . . . . . . . . . . . . . . . . . . . . . . 17
3.2.2 角度之參數模型. . . . . . . . . . . . . . . . . . . . . . . . 17
3.3 最大概似定位演算法. . . . . . . . . . . . . . . . . . . . . . . . . . 18
3.4 非視線基地台判別演算法. . . . . . . . . . . . . . . . . . . . . . . 19
3.4.1 TOA判別非視線基地台演算法. . . . . . . . . . . . . . . . . 19
3.4.2 改良型TOA 判別非視線基地台演算法. . . . . . . . . . . . 25
3.4.3 混合型TOA/AOA 判別非視線基地台演算法. . . . . . . . . 26
3.4.4 LOS基地台最佳選取演算法. . . . . . . . . . . . . . . . . . 31
4 電腦模擬與分析33
4.1 各種不同非視線基地台個數下之定位誤差模擬. . . . . . . . . . . . . 33
4.1.1 不同時間量測誤差之影響. . . . . . . . . . . . . . . . . . . 34
4.1.2 不同角度量測誤差之影響. . . . . . . . . . . . . . . . . . . 41
4.1.3 不同角度偏移之影響. . . . . . . . . . . . . . . . . . . . . . 43
4.1.4 不同空間大小之影響. . . . . . . . . . . . . . . . . . . . . . 46
4.1.5 不同行動台位置之影響. . . . . . . . . . . . . . . . . . . . . 50
4.1.6 不同基地台間不同的時間量測誤差之影響. . . . . . . . . . . 52
4.2 非視線基地台鑑別準確度之模擬. . . . . . . . . . . . . . . . . . . . 55
4.3 模擬結果探討與總結. . . . . . . . . . . . . . . . . . . . . . . . . . 57
5 結論與建議58
參考文獻58

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