A Bluetooth signal strength based indoor localization method

Indoor location awareness is intended for many applications like patient monitoring and store navigation. Short range wireless protocols are usually preferred when other ways of location sensing methods such as Global Positioning Systems or Inertial Measurement Units may not be feasible to use indoors. Devices using Bluetooth protocol have the advantage of being low cost and also being widely available. In this paper an affordable indoor localization system is proposed where location evaluation is performed by measuring unknown positioned Bluetooth transmitters´ signal levels at some known base stations. A localization method is proposed which uses calculated values of a defined error function to estimate the positions of unknown transmitters. The error function is based on a modified Root-Mean-Square-Error (RMSE) metric. The error function is calculated using Received Signal Strength Indicator (RSSI) measurements at each point under consideration. The error function is calculated at discrete points in the area of interest and the points with low calculated error values indicates locations where transmitters may be located with a high probability. The validity of the decision method is verified with a real-world experiment.