Wireless Local Area Network (WLAN)
Indoor positioning via WLAN: WLAN means Wireless Local Area Network and designates a local radio network. The positioning accuracy is five to 15 meters. Under ideal conditions, location would be possible with an accuracy of 0.5 m. However, these are never achieved in practice.
Infrastructure often already available
no log-in required
numerous disturbing factors
numerous devices no longer support positioning
When positioning via WLAN, the receiver (smartphone, tablet) measures the signal strength of a large number of hotspots positioned in the building. The position is determined by trilateration. The biggest advantage of this technology is that a WLAN infrastructure – consisting of access points and, for example, network-compatible devices such as WLAN-compatible POS systems – already exists in many cases and no new infrastructure needs to be set up. Additionally a log-in is not necessary, because only the signal strength is measured. However, this indisputable advantage is outweighed by numerous disadvantages. For example, end devices with iOS version 4.3 or higher do not support location via WLAN. Meanwhile the operating system version 11 is already up to date. A high number of users is thus already excluded by the technical requirements. Calibration of the position determination must also be carried out in advance using reference measurements, which makes installation extremely time-consuming. In indoor navigation, the smart device is based on the strength of the WiFi signals (Received Signal Strength Indication, RSSI for short). Human bodies have already proven to be significant disruptive factors in this methodology. This is due to the high water content of a body (over 70%) and the resonance frequency of the water, which is around 2.4GHz, the frequency at which many wireless local networks are also operated.
Google uses WLAN for its Google Indoor Maps. According to its own statement, Google is “currently concentrating on locations with heavy public traffic such as airports, shopping malls, stadiums and bus stops”. According to Google, around 20 buildings with indoor positioning are currently available in Germany*.