You want to detect the smartphone’s presence in a particular zone.
For instance, you want to count the number of staff in a particular room.
Beacons are considered to be magnets. The SDK will compute all surrounding BLE signals and identify the strongest one. By definition, the strongest beacon is the one with an RSSI value higher than a certain threshold through a certain number of scan cycles. Developers can configure the threshold and number of scan cycle values.
How many beacons?
You will need at least one beacon per zone. The zone may be too big or contain some obstacles that could deviate the Bluetooth signals. In this case, you can add more beacons to make sure your zone is fully covered.
Where to attach the beacons?
You can attach them to walls, furniture and the ceiling. Again, try avoiding metallic surfaces, since BLE signal easily bounces on those kinds of surfaces, hence decreasing the RSSI.
If the threshold is too low, the algorithm might fluctuate between different beacons, each time sending a strong signal, even if you don’t move.
If the number of scan cycles is too big, it adds a latency to detect the strongest beacon.