BLUETOOTH

Bluetooth® is widely used for data transfers over short distances, using the same radio frequency as WiFi – 2.4 GHz. One special feature of Bluetooth is that it only has a very small power requirement.
Bluetooth can be used to make distance measurements and proximity measurements – these are two different ways to use the technology for determining a position.

Bluetooth distance measurements

When Bluetooth is used to undertake distance measurements, this is based on the fact that Bluetooth transmitters only have a short range. This, however, makes it necessary to set up a large number of transmitters in order to make the measurements needed for trilateration.
Bluetooth transmitters are relatively inexpensive, and the use of many measuring points makes such a solution more accurate than – for example – WiFi.
On the other hand, there is a major challenge associated with the maintenance of such a network of Bluetooth transmitters. Furthermore, since Bluetooth uses the same frequency as WiFi, this type of network has a disruptive effect on WiFi networks.

Bluetooth proximity measurements

The challenge associated with the need to set up multiple Bluetooth transmitters can be solved by setting up a smaller number of transmitters at specially selected sites, and then making use of the fact that the transmitter can conclude where the receiver is located, within a short range.

iBeacon

When considering Bluetooth and tracking, it is also necessary to mention iBeacon, which is a special Bluetooth protocol published by Apple. This protocol specifies a particular type of transmitter unit called iBeacons, which broadcast ID information and signal power. These can then be used to deduce the location of the receiver.
This solution is particularly intended for retail stores, which can employ iBeacon technology to provide position-based information to customers using a Bluetooth Low Energy (BLE) device.
iBeacon solutions can also be used to provide cheap transmitters for a more general positioning.
It should also be mentioned that the Bluetooth implementations on the Android platform are not yet sufficiently mature for communication with multiple Bluetooth transmitters at the same time.