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Basic principles of Positioning

Indoor positioning follows the same principle as outdoor positioning using the familiar Global Positioning System (GPS). GPS is a global navigation satellite system for position determination. In order to function reliably, it requires a free “line of sight” to several satellites (theoretically three, in practice six to twelve satellites). This condition can already be limited outdoors by scenic or architectural conditions, indoors there is hardly any chance of undisturbed GPS reception.

 

GPS receivers can calculate their own position and speed from the signal propagation times. In combination with geoinformation (topology, road, air or sea maps), this position information enables guidance to a selected location or a route, taking into account desired criteria. Simplified even more: Transmitters send radio signals to a receiver. The receiver interprets these signals and calculates its position within a given topography. The principles behind this are trilateration and triangulation.

These three elements – transmitter, receiver, environmental information – can also be found in radio-based indoor navigation systems, especially in indoor navigation with the help of Bluetooth low-energy transmitters, the so-called iBeacons.
Beacons only send information about their own identity. The unique fingerprint of each Beacon is made up of the values UUID, Major ID and Minor ID. The UUID (Universally Unique Identifier) is a standard identifier commonly used in software development. With the help of the UUID all beacons of a network can be identified. For example, under the UUID, all beacons are grouped under the control of a particular shopping center operator. The major ID then designates all beacons within a specific shopping center, the minor ID a specific beacon within the shopping center. Positioning with the aid of light, such as the Philips Lighting Indoor Positioning System, works with special LEDs that function as a “transmitter/satellite”. Their light signals transmit an individual coding for each luminaire, which contains corresponding information on their position.

 

A smart device equipped with an appropriate app, a smartphone or a tablet, can interpret beacon, light or WLAN signals on the basis of their strength and with the help of the topographical information stored as a “floor plan” and determine its own position, i.e. the position of the user, within the structural unit covered by beacon signals. From this position, a route to any point of interest within the beacon installation, i.e. the area covered by signals, can be calculated and displayed.