FUSION OF LOCATION FINGERPRINTING AND TRILATERATION BASED ON THE EXAMPLE OF DIFFERENTIAL WI-FI POSITIONING
Positioning of mobile users in indoor environments with Wireless Fidelity (Wi-Fi) has become very popular whereby location fingerprinting and trilateration are the most commonly employed methods. In both the received signal strength (RSS) of the surrounding access points (APs) are scanned and used...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-09-01
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| Series: | ISPRS Annals of the Photogrammetry, Remote Sensing and Spatial Information Sciences |
| Online Access: | https://www.isprs-ann-photogramm-remote-sens-spatial-inf-sci.net/IV-2-W4/377/2017/isprs-annals-IV-2-W4-377-2017.pdf |
| Summary: | Positioning of mobile users in indoor environments with Wireless Fidelity (Wi-Fi) has become very popular whereby location
fingerprinting and trilateration are the most commonly employed methods. In both the received signal strength (RSS) of the
surrounding access points (APs) are scanned and used to estimate the user’s position. Within the scope of this study the
advantageous qualities of both methods are identified and selected to benefit their combination. By a fusion of these technologies a
higher performance for Wi-Fi positioning is achievable. For that purpose, a novel approach based on the well-known Differential
GPS (DGPS) principle of operation is developed and applied. This approach for user localization and tracking is termed Differential
Wi-Fi (DWi-Fi) by analogy with DGPS. From reference stations deployed in the area of interest differential measurement
corrections are derived and applied at the mobile user side. Hence, range or coordinate corrections can be estimated from a network
of reference station observations as it is done in common CORS GNSS networks. A low-cost realization with Raspberry Pi units is
employed for these reference stations. These units serve at the same time as APs broadcasting Wi-Fi signals as well as reference
stations scanning the receivable Wi-Fi signals of the surrounding APs. As the RSS measurements are carried out continuously at the
reference stations dynamically changing maps of RSS distributions, so-called radio maps, are derived. Similar as in location
fingerprinting this radio maps represent the RSS fingerprints at certain locations. From the areal modelling of the correction
parameters in combination with the dynamically updated radio maps the location of the user can be estimated in real-time. The novel
approach is presented and its performance demonstrated in this paper. |
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| ISSN: | 2194-9042 2194-9050 |