Local Positioning Systems
Encyclopedia
A local positioning system (LPS) is a navigation system that provides location information in all weather, anywhere within the coverage of the network, where there is an unobstructed line of sight
to three or more signaling beacons of which the exact position on earth is known. A special type of LPS is the Real-time locating system
; which also allows real-time tracking of an object or person.
or other global navigation satellite system
s, local positioning systems don't provide global coverage. Instead, they use (a set of) beacons which have a limited range, hence requiring the user to be near these. Beacons include cellular base station
s, Wi-Fi
access points (used by the Skyhook Wireless
system), and radio broadcast towers.
In the past, long-range LPS's have been used for navigation of ships and aircraft. Examples are the Decca Navigator System
and LORAN
.
Nowadays, local positioning systems are often used as complementary (and in some cases alternative) positioning technology to GPS, especially in areas where GPS does not reach or is weak, for example, inside buildings, or urban canyon
s.
Local positioning systems using cellular broadcast towers are also heavily used to determine the current position of a person (carrying a cellphone without GPS-capability), ie for a wide array of services. See Mobile phone tracking
to calculate the position of an object.
Line-of-sight propagation
Line-of-sight propagation refers to electro-magnetic radiation or acoustic wave propagation. Electromagnetic transmission includes light emissions traveling in a straight line...
to three or more signaling beacons of which the exact position on earth is known. A special type of LPS is the Real-time locating system
Real-time locating system
Real-time locating systems are a type of local positioning system that allow to track and identify the location of objects in real time. Using simple, inexpensive badges or tags attached to the objects, readers receive wireless signals from these tags to determine their locations...
; which also allows real-time tracking of an object or person.
Use
Unlike GPSGlobal Positioning System
The Global Positioning System is a space-based global navigation satellite system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites...
or other global navigation satellite system
Global Navigation Satellite System
A satellite navigation or SAT NAV system is a system of satellites that provide autonomous geo-spatial positioning with global coverage. It allows small electronic receivers to determine their location to within a few metres using time signals transmitted along a line-of-sight by radio from...
s, local positioning systems don't provide global coverage. Instead, they use (a set of) beacons which have a limited range, hence requiring the user to be near these. Beacons include cellular base station
Base station
The term base station can be used in the context of land surveying and wireless communications.- Land surveying :In the context of external land surveying, a base station is a GPS receiver at an accurately-known fixed location which is used to derive correction information for nearby portable GPS...
s, Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
access points (used by the Skyhook Wireless
Skyhook Wireless
Skyhook Wireless is a Boston-based company that developed a technology for determining geographical location using Wi-Fi as the underlying reference system. Using the MAC addresses of nearby wireless access points and proprietary algorithms, Skyhook's Wi-Fi Positioning System WPS can determine...
system), and radio broadcast towers.
In the past, long-range LPS's have been used for navigation of ships and aircraft. Examples are the Decca Navigator System
Decca Navigator System
The Decca Navigator System was a low frequency hyperbolic navigation system that was first deployed during World War II when the Allied forces needed a system which could be used to achieve accurate landings...
and LORAN
LORAN
LORAN is a terrestrial radio navigation system using low frequency radio transmitters in multiple deployment to determine the location and speed of the receiver....
.
Nowadays, local positioning systems are often used as complementary (and in some cases alternative) positioning technology to GPS, especially in areas where GPS does not reach or is weak, for example, inside buildings, or urban canyon
Urban canyon
An urban canyon is an artefact of an urban environment similar to a natural canyon. It is manifested by streets cutting through dense blocks of structures, especially skyscrapers, which causes a canyon effect...
s.
Local positioning systems using cellular broadcast towers are also heavily used to determine the current position of a person (carrying a cellphone without GPS-capability), ie for a wide array of services. See Mobile phone tracking
Mobile phone tracking
Mobile phone tracking refers to the attaining of the current position of a mobile phone, stationary or moving. Localization may occur either via multilateration of radio signals between radio towers of the network and the phone, or simply via GPS...
Techniques
An LPS can either use:- triangulationTriangulationIn trigonometry and geometry, triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly...
- trilaterationTrilaterationIn geometry, trilateration is the process of determinating absolute or relative locations of points by measurement of distances, using the geometry of circles, spheres or triangles. In addition to its interest as a geometric problem, trilateration does have practical applications in surveying and...
or - multilaterationMultilaterationMultilateration is a navigation technique based on the measurement of the difference in distance to two or more stations at known locations that broadcast signals at known times. Unlike measurements of absolute distance or angle, measuring the difference in distance results in an infinite number of...
to calculate the position of an object.
Commercial systems
Commercial systems on the market and/or in progress include:- Microsoft's RADAR
- Ekahau's RTLS
- Zebra Technologies Corporation RTLS WhereLAN
- Awarepoint RTLS
- Skyhook WirelessSkyhook WirelessSkyhook Wireless is a Boston-based company that developed a technology for determining geographical location using Wi-Fi as the underlying reference system. Using the MAC addresses of nearby wireless access points and proprietary algorithms, Skyhook's Wi-Fi Positioning System WPS can determine...
See also
- Indoor positioning systemIndoor Positioning SystemAn indoor positioning system is a term used for a network of devices used to wirelessly locate objects or people inside a building. Generally the products offered under this term do not comply with the International standard ISO/IEC 24730 on real-time locating systems . There is currently no de...
- Hybrid positioning systemHybrid positioning systemHybrid positioning systems are systems for finding the location of a mobile device using several different positioning technologies. Usually GPS is one major component of such systems, combined with cell tower signals, wireless internet signals, Bluetooth sensors or other local Positioning...
- Real-time locating systemReal-time locating systemReal-time locating systems are a type of local positioning system that allow to track and identify the location of objects in real time. Using simple, inexpensive badges or tags attached to the objects, readers receive wireless signals from these tags to determine their locations...