A feasible economic technique for indoor positioning using the received signal strengths (RSSs) of mobile devices and Global Positioning System (GPS) orbital data was developed in this study. The RSSs transmitted from a Wireless Fidelity (WiFi) access point (AP) must be detected by a mobile device and transformed into the near light-of-sight (LOS) ranges with a self-adoptive model defined for a specific indoor area. A new approach using a single WiFi AP and four selected GPS satellites was proposed and tested for indoor positioning. The WiFi-detected range and the GPS orbit-computed range can be combined into a geometric range and applied in GPS-like positioning. To absorb the biases related to the non LOS, a linear fitting and removal process was accompanied. The test results showed an 85% success rate with average positioning errors of 3.7 m and 2.0 m in the plan and vertical components, respectively. This WiFi/GPS hybrid approach has shown potential for accurate and reliable indoor 3D navigation positioning.

本研究提出一項利用行動裝置獲取信號接收強度並配合GPS軌道資料，以進行室內定位之便捷技術。由單一WiFi發射點所發送的信號接收強度由行動裝置感測後，透過該特定區域之一組自適化模型轉化為近直視距離，再配合所選定之GPS衛星位置，即可進行室內空間之三維定位作業。此一組合式之定位方法，係運用WiFi感測距離與GPS軌道計算距離進行幾何空間距離之組合，在效益上可使用最少數量之WiFi發射點布設條件，配合4顆固定之GPS衛星位置，即可進行類似GPS的室內導航定位。實際定位時，另須引入線性偏差的擬合及移除程序，以吸收與非直視距離相關之偏差量。由現地測試成果可知，新方法的定位成功率為85%，平面及垂直方向的定位誤差則分別為3.7公尺及2.0公尺，顯見此一運用WiFi/GPS的組合定位法，已在室內三維導航定位上，具備足夠精度及可靠度之應用潛能。