A Measurement Study of BLE iBeacon and Geometric Adjustment Scheme for Indoor Location-Based Mobile Applications

Figure 15

[Case  1] where two distance circles (circles representing the estimated distance using RSSI) from two iBeacons are nonintersecting because the sum of two distance estimations are smaller than the distance between the two iBeacons. This results in no intersection point for trilateration calculation. Thus, we gradually increase the sizes of the circles until they intersect.