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

Figure 16

[Case  2] where a distance circle (a circle representing the estimated distance using RSSI) from one iBeacon is completely enclosed by another distance circle (from another iBeacon), resulting in no intersection point for trilateration calculation. In this case, we gradually increase the size of the inner circle until the two circles intersect.