目前由於網際網路的成長造就手機市場的蓬勃發展,智慧型手機及無線通訊的相關應用也越來越多(包含WiFi, 藍牙, 3G/4G行動上網)。藍牙由於有普及率高及低功耗的特性, 因此成為多數室內定位相關研究的選擇, 而傳統的藍牙由於傳輸距離的限制, 因此在室內定位的議題上面的限制相對較大, 通常用於近距離偵測, 而在藍牙4.0後由於傳輸距離的增加, 也賦予藍牙室內定位應用的更多機會。 本論文實作在Android 手機上透過接收藍牙RSSI(received signal strength indicator)強弱以定義兩個裝置相對距離的遠近, 透過實作三種演算法來探討當距離改變對RSSI訊號的影響。 The applications of wireless communication systems (WiFi, Bluetooth, 3G / 4G networks) are booming for the growth of internet. The indoor positioning technologies using the Bluetooth 4.0 are the very important in the proximity services. We have implemented the Android APP to indicate the relative distance between the several Bluetooth devices via receiving the RSSI(Received Signal Strength Indicator).