Ubiquitous User Localization for Pervasive Context-Aware Construction Applications - Mobile and Pervasive Computing in Construction - page 109

Figure 6.24 Virtual representation for indoor tracking of a mobile user using
WLAN (Civil Engineering Department)

An experiment was performed at NIST, specifically in the “maze” at the former
NIKE missile base barracks building adjacent to the main campus (Figure 6.25).
The test bed used was similar; three access points were used and the user navigated
around the “maze” and collected position information.
A final experiment was conducted in the Structural Engineering Laboratory on
the first floor of the GGB building at the University of Michigan (Figure 6.26). The
WLAN indoor positioning test bed has an area of 40 25 ft and contains various

structural elements including concrete walls and columns, steel columns and beams
(Figure 6.27).
As aforementioned, area calibration and data collection follow the training
phase of the fingerprinting approach. The signal strength measuring device
(laptop or any other WLAN-enabled device) is set at a predetermined RP position
and data are collected fromeach access point in the area and saved to the database.
The user then advances to the next RP and collects signal data again. In this
experiment, several RPs were chosen. The dots shown in Figure 6.28 are different
RPs located on tracking rails. As stated earlier in this section, university access
points deployed in the different buildings across campus, as part of a wireless
network, were used.
Having created the fingerprint database, signal strength data were collected at
each mobile user's location while inspecting the different structural objects of the

Figure 6.25 Maze at Nike Site (NIST)