What is the current status of positioning and navigation in buildings? PC-WELT tried different systems and explains the technologies behind it.
Where is the car rental company at the airport, where is the regiment with blinds in the hardware store, where the x-ray department is located in the hospital, and where is the popular exhibition in the museum? Four examples that show how easy it would be in everyday life, even if you could move in buildings like the outside.
Because of the strong navigator in the car and routing using a smartphone, we are spoiled. In most cases, the device or application tells us where to go for a few meters. How good it would be if you could navigate electronically in shopping centers, museums and other structures, some of which were barely manageable and brought them to their destination.
Internal navigation is still in its infancy
Internal navigation works very differently than the positioning from the outside through the satellites used in the car and on the phone. There, the location is mainly retrieved by the satellite signals of the American GPS system, although much more than 100 smartphones can also receive a Russian satellite. In the end, a system called Glonass has been running for three years.
Navigation with free hiking maps
But unlike mobile communications, this place requires direct line of sight of satellites, so GPS and Glonass do not work in space. If the smartphone still correctly displays the location there, this is due to localization via well-known Wi-Fi networks in an area that uses the phone in addition to satellites called Assisted GPS (A-GPS).
Traditional Wi-Fi is also a technology that Google has been using for its indoor cards for two years. Like Wi-Fi support for A-GPS, the signal intensity of various hot spots is measured, and the location is determined by trilateration. If a sufficient number of WLAN transmitters is available, the position in the interior can in principle be determined up to ten meters. By the way, without this, you have to log in somewhere, after all, you only need signal strength.
For a long time Wi-Fi had a clear advantage that it was the only technology that could fit into almost any smartphone and could be used by almost everyone. But even two years after the start of the project, the practical implementation of Google Indoor Maps in all the buildings we tested is very unsatisfactory. First, the ability to use the usual Google Maps application for interior orientation is limited to a short number of buildings. There are three airports in Germany, two football stadiums, several museums, and various shopping centers and shops, including Saturn and Ikea.
Secondly, the system is not working properly. Because in principle, you need to zoom in on the smartphone in a well-equipped design, far enough in the Maps application, then open the saved Google plans, and then determine the Wi-Fi position as far as possible. But in practice, you either see yourself as inaccurate or often mistakenly placed: sometimes your own location must be somewhere there, sometimes the “accuracy specification” covers the entire floor, sometimes you are on the wrong floor. Of course, this is of little use if you are looking for a department in a department store or in a museum.
The Awiloc-supported WLAN system of the Fraunhofer IIS Integrated Circuit Institute in Erlangen, which is currently used in five German museums, is much more accurate in practice. Here, visitors will receive a tablet with a special guide, which, among other things, provides a “free tour” with object information or special tours, including for children.
We tried the system at the Museum of Egyptian Art in Munich. He always correctly positioned us in the building, in large salons, in the right place in the room. The operation and user manual of the application installed on Samsung tablets turned out to be a bit tedious, but technicians can hardly be difficult here. Therefore, location determination and, therefore, trilateration worked well, therefore the Wi-Fi location should be implemented only with a sufficient number of radio transmitters.
Bluetooth 4.0: beacons as an alternative to localizing WLAN
In addition to WLAN, more and more mobile devices support Bluetooth 4.0 (Bluetooth Low Energy, BLE). Apple already equipped the iPhone 4S in 2011, and from the BLE software side was supported two years later with iOS 7 and iBeacon technology. Google's operating system can handle Bluetooth 4.0 with Android 4.3, in addition, the smartphone or tablet must support BLE. The localization technique works similarly to a WLAN, namely by measuring the signal intensity of Bluetooth transmitters (beacons) distributed throughout the building.
Meanwhile, several stores use Beacon support in their applications, including Apple, in their stores in the United States. This allows dealers to send local push messages to their customers, for example, a special offer or personal recommendation in front of a wine rack. How it works in practice shows a short video on Macy's department store network.
The Beacon technique was tested using the Easyjet application. Recently, the airline provided orientation at three European airports via Bluetooth and an app (currently only iOS). Among other things, passengers should be piloted to the gate and recalled at the local level, for example, about the opening of the boarding pass - at Gatwick Airport in London, the system seems to be inactive in our test.
This is the status quo. The internal location can be really convenient if it offers navigation inside the building, like in a car, that is, “straight ahead, right here, on the elevator to the third floor ...”. In addition, there are already pilot projects in which arrows and hints are placed on the screen of a mobile phone through augmented reality on the camera image.
Methods for internal positioning
Finally, we explain the various technologies that are used for internal positioning and navigation.
Satellite reception and mobile radio: modern smartphones rely on a combination of GPS (and the Russian equivalent of Glonass), radio cell of the mobile network and identification of locally known WLAN networks. Inside buildings, however, GPS positioning does not work, as it requires visual contact with satellites. The mobile radio station, in turn, is too inaccurate because the radio elements are too large.
WLAN: when positioning via a WLAN, the receiver (smartphone, tablet) measures the signal intensity of a large number of hot spots located in a building. Trilateration determines the position.
Low energy Bluetooth: in principle, localization works via Bluetooth 4.0, the transmitter (beacons) has a range of about 30 meters. Position accuracy can be reduced by various corrective measures to five meters.
Other systems: inertial systems work without radio communication, which measure the direction and speed of movement far from a certain point. In accordance with this principle, a gyrocompass, a milestone of navigation at sea, operates. In addition, Philips "Visible Light Communications" (VLC): a lighting system that generates local light pulses in addition to ordinary light. They are captured and evaluated using a smartphone, the application shows the location in a well-equipped building. The barometer helps to measure air pressure in high-rise buildings while displaying the floor. Finally, spatial location can echo, since it is also used by bats.