The Global Positioning System or GPS is now a familiar technology to everyone who owns a smartphone. But everyone also knows that GPS and other satellite technologies lack precision or fail entirely inside multistory buildings, parking garages, and underground locations. Since GPS is unreliable in interior spaces, accurate Indoor Positioning Systems have been developed in the past few years. An Indoor Positioning System is a network of devices used to locate people or objects using a variety of techniques. These devices provide indoor positioning ranging from reconfigured devices already deployed such as smartphones, WiFi and Bluetooth antennas, digital cameras, and clocks to purpose-built installations with relays and beacons strategically placed throughout a defined space.
Wi-Fi-based positioning systems locate and monitor active Wi-Fi tags such as smartphones, tablets and Wi-Fi tags. As these tags are Wi-Fi transmitters, they send simple packets to a number of WiFi access points in a facility. These access points report the time and strength of that reading to a backend, which uses algorithms to compute position. Then, the location information is sent to the cloud. The accuracy of Wi-Fi used for server-based indoor localization varies from eight to 15 meters – depending on the preconditions.
The most important 3 benefits of Wi-Fi-based IPS are:
- The ability to track all Wi-Fi-enabled devices
- The ability to monitor visitor behavior
- Large range (up to 150m)
BLUETOOTH LOW ENERGY (BLE) BEACONS
Beacons are small wireless devices that broadcast signals using Bluetooth Low Energy, also known as Bluetooth Smart. They are relatively cheap, can run on button cells up to more than five years and have a maximum range of 75 meters. Accuracy is typically less than eight meters. Beacons come in all kinds of different formats, are scalable and highly portable.
Indoor Positioning Systems using Bluetooth beacons are flexible and cost-efficiency
Ultra-wideband is a short-range radio technology. In contrast to Bluetooth Low Energy and Wi-Fi, positioning is done with transit time methodology (Time of Flight, ToF) instead of the measurement of signal strengths (Receive Signal Strength Indicator, RSSI). This method measures the running time of light between an object and several receivers. At least 3 receivers are necessary (trilateration) to exactly locate an object. Also, there must be direct line-of-sight between receiver and transmitter. The accuracy is less than 30 cm, which is considerably better than when working with beacons or Wi-Fi. This technique offers accurate measurement of height differences as well.
The high accuracy, low latency times with position updates up to 100 times/second with almost no interferences make for a significant advantage.
RFID, or Radio Frequency Identification, is a form of wireless communication that uses radio waves to identify objects. Passive RFID is used in IPS technology, but it works only in the proximity of specialized RFID readers, providing a ‘point-in-time’ location.
The benefits of RFID very high accuracy, very immune to interferences and no battery is needed
CORRELATION OF IMAGE AND POSITION DATA
With this new technique, linking position data of persons, vehicles or objects with images of installed CCTV cameras not only enables allocation of visual characteristics (e.g., color features) but also compensates for inadequate positional accuracy by comparison with a different image.
In conclusion, no single solution is a silver bullet for creating an Indoor Positioning System that fits all possible needs. Usually, finding the most suitable technology requires evaluating the requirements, the conditions on-site, and the budget. More often, the most efficient solution is a combination of techniques.