The main algorithms used to compute locations from RF signals are the following:
- Received Signal Strength Indicator (RSSI) technique is highly appreciated because of its minimal complexity. It can be used to detect the asset by zone using only one anchor in the middle of the zone, or to locate the asset on a line between two anchors or to locate the asset with a dot on a map with x,y coordinates.
- Time Difference of Arrival (TDoA) technique uses multiple reference points (anchors) that are time synchronised so that when they receive a signal from a tag on a moving asset, a multilateration algorithm will compute the tag position based on the time difference of arrival of the signal sent by the tag to the different anchors. This technique enables to calculate the position of thousands of tags simultaneously with down to 20-30cm thanks to UWB.
- Two-Way Ranging (TWR) technique relies on two-way communication between two devices where the time of flight of the signal exchange is used to measure the distance between the two devices as the signal speed is known.
- Angle-of-Arrival (AoA) technique is based on the measurement of the angular directions (Azimuth and Elevation) from the Tag to the Anchor using directional antennas or antenna arrays. This direction can be calculated through the phase differences of the elements of an antenna array.