近年來，不論是在學術研究或是產業應用，行動定位系統已受到廣泛的注意。而由於在無線通訊商業服務中，移動用戶對基於無線定位技術所產生的新業務需求，亦推動了對無線測距及定位技術的深入研究。而多種加值服務亦已被開發或引進，如因所在位置而有不同通話計費方式、交友服務、購物資訊、優惠卷發放、行車輔助導航系統、資源管理及緊急報案之定位(E-911)等。

在蜂巣式無線網路中，造成手機定位誤差的來源一般可區分為兩種:一類是由網路中的基站與使用者手機間時序非同步所產生的誤差，另一類則是於無線通訊環境中因障礙物所引起的非視線傳遞訊號。對於前者，我們可以採用訊號抵達時間差此種定位技術來於以消除，而後者卻往往是造成定位誤差最大的因素，因其會造成量測距離總是大於實際距離的現象，所以也是我們主要研究的課題。

於本論文中，先對常使用於模擬中的非視線誤差環境做一模型建立，而後利用誤差統計模型做誤差類型之判別，再利用動差估測法做為降低定位誤差的機制，最後才以加權式最小平方估測法、最大可能性估測法針對各個量測修正結果去計算手機位置。而我們亦將定位結果與克連美-羅下限值比較，以做為效率評估依據。而模擬結果亦呈現不論手機是在何種相對位置下，皆可獲得令人滿意之預估精確度。

Both in research and in commercial applications, the mobile positioning system has received considerable attention in the recent years. Many value-added application services have been developed and introduced to subscribers, such as location sensitive billing, friend-finding, shopping information, coupon delivery, driving directions, resource management, and wireless E911, etc.

The major error sources in the cellular network include measurement noise and non-line-of-sight (NLOS) propagation error. The former is caused by the clocks asynchronous between the base station and mobile terminal. The latter arises due to the obstacle between receiver and transmitter, and it’s the dominant factor which makes the measured distances larger than the true ones. We will focus on the reduction of NLOS error in this paper.

In this thesis, we propose an algorithm to solve it with the following steps: 1.build models to simulate the NLOS error environment, 2.judge the error model by collecting the statistical information for the distribution of measurements, 3.reduce the error by the proposed moment method, 4.estimate the location by applying the maximum-likelihood estimation and weighted least-square estimation methods, 5.compare with Cramér-Rao lower bound. The result of solving such positioning issue with our proposal is satisfactory.

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