The 3 P's of Location - Presence, Proximity and Positioning

The 3 P's of Location

When using any sort of Radio frequency to locate assets there are in general 3 types of location

that one would consider. Presence, Proximity or accurate Positioning. In a nutshell the way to

solve each consequent P is to add more locators gateways closer to each other. 

The more locator gateways the more accurate the position can be determined. 

Presence

 If you have one BLE gateway for instance that is sniffing BLE beacons then you will know

within 10's of meterswhether a device is near the gateway or not. This very inaccurate device ID

capturing would be considered Presence as you would know whether a beacon is near or in the

presence (field of view) of the gateway. This is helpful for instance where you want to know

whether a person or asset is in a warehouse but you don't need to know in which bin it is for

instance. 

Proximity

 If you were to place 4 gateways, one at each corner of a warehouse, you would be able to
calculate the proximity of the beacon to the closest gateway. By using triangulation or trilateration
you would be able to calculate by either using the RSSI - Received Signal Strength Indicator or
one of the other more technical algorithms to determine more accurately the proximity to one
of the gateway for each beacon. 

Position

 However, for more accurate positioning of the beacon you would have to place many gateways

over the whole warehouse at close intervals in a grid array. This would use the algorithms

mentioned above to calculate how close the beacon is to a set of gateways and then where

the beacon is spatially in relation to the gateways. This accurate positioning requires many

gateways to be successful. 

RFID

RFID having a much closer range than BLE or WiFi RF signals needs to have many more
gateways but the beacons (stickers) are extremely cheap compared to BLE beacons so the
gateways and antennas become a larger capital outlay but the cost of a few hundred
thousand tags quickly makes sense because each tag is so cheap. So large capital
outlay for antennas and readers but cheap stickers make this a good scenario for
certain use cases. 

 If you would like to be able to see which rack an asset is then you would have an antenna and

reader per rack with RFID, whereas with BLE or WIFI the beacons can send their signals way

further, sometimes 80 meters or more. So then you would use fancy algorithms to figure

out where each beacon is situated. 

Written by John K Weber - IoTdc

Here is an excellent article explaining a bit more in detail the points mentioned above by

an amazing tracking company called Quuppa. Click here for article