Method for Improving Indoor Positioning Accuracy Using Extended Kalman Filter

Table 1

Four proximity states of iBeacon.

Glossary	Description
Accuracy	A distance value in terms of meters
Proximity state (estimates of the distance between the iBeacon transmitter and the smartphone that appears in the CLBeacon class)	(i) Immediate: distance between 0 and 1 m; high reliability.; (ii) Near: distance between 1 and 3 m; trusted distance.; (iii) Far: distance greater than 3 m. The measured distance is not the actual distance to the iBeacon transmitter.; (iv) Unknown: iBeacon signal is not received.; Measurement reference value: the RSSI values (−59 dBm) received at a distance of 1 m.