雖然GPS定位服務有著高精度的成果，但是視線傳播效應的影響使的他無法應用於室內的情況，如果能建立GSM無線通訊系統為定位技術的開發，就能利用不同的訊號傳播，如信號傳送時間(Time of arrival)、時間前置法(Timing Advance, TA)、訊號接收角度(Angle of arrival)、接收訊號角度(Received signal strength)作為室內定位的方法。
本論文以 GSM無線通訊系統的基地台接收訊號強度做室內定位，利用訊號強度與距離的關係來做位置的估算。本文利用一組通訊模組為行動單元於電腦進行定位的運算，藉由程式的TA指令執行初始化、開機、啟動模式等等，並且擷取相對的RSS值。本方法能快速且精確的獲得室內定位數據，惟目前受到一些干擾，計算成功比率偏低，有待改進。然而本方法仍可合理的加以推廣應用。

Although Global Positioning System (GPS) has been verified to offer high accuracy positioning, it is limited by line of sight signals from satellites that indoor applications are not available. Based on the GSM signal propagation, an improved indoor positioning technique using time of arrival (TOA), angle of arrival (AOA) and received signal strength (RSS) is developed in trial.
In this study, a mobile station is used based on received signal strength for GSM positioning. The method calculates directional signals from vincinity base transceiver stations (BTS). An algorithm is formulated to obtain their received signal strength (RSS) value from each BTS. To set up the reference locations for positioning, a BTS database is established from the supports of system providers. From several experiments, the performance and efficiency of the mobile positioning are improved with obviously better results. However, the positioning success rate is still lower than expected due to the BTS interference and signal multipath. This methid is feasible into applications.

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