A study on indoor position estimation based on fingerprinting using GPS signals

It is impossible to observe the Global Positioning System (GPS) signal traveling in Line of Sight (LOS) indoors. When the position is estimated by using Non-LOS GPS received signals, it results in serious positioning error because the conventional estimation method by the GPS supposes the GPS signals in LOS. However, we may observe reflected signals from the GPS satellites even if indoors. Thus, we consider that the reflected received signals are useful for a reference of the position estimation although it is impossible to directly estimate the position. Supposing that the Received Signal Strength Indicator (RSSI) of the GPS signal varies between locations, we create a database of the RSSI of the GPS signal in each location such as the well-known fingerprinting method. It is possible to estimate the user location by querying the database even if indoors. By experiments, we evaluate the proposed method and propose a shrink method for the database additionally. We show that the proposed method can estimate indoor location well enough.