Algorithm 1 BLE-driven trilateration method.

1: while accepted distances $i\ge$ Threshold ${\tau }_1$ do

2:  collect the RSSI readings from n BLE modules

3:  if the RSSI is registered then

4.   apply the Kalman filter

5:   compute the distance $d_i$

6:  end if

7:  if $d_i>$ Threshold ${\tau }_2$ then ignore $d_i$

8:   go to Step 2

9:  end if

10: end while

11: apply the multilateration for i distances

12: apply the average filter and update the position