Ubiquitous User Localization for Pervasive Context-Aware Construction Applications - Mobile and Pervasive Computing in Construction - page 97

Figure 6.6 Ekahau deployment and calibration
The Ekahau Client is a free downloadable piece of software that is responsible for
sending the recorded RSSWLAN signals to the EPE. These signals play a major part
in determining users' position and are also used by the EkahauManager application
to perform SiteCalibration . The Ekahau Manager is mainly responsible for the
patented process called SiteCalibration (Figure 6.6). Firstly, it creates a model of the
desired area in the form of an accurate floor map image (this can be in JPG, PNG or
BMP format). Then, tracking rails are drawn on top of the map to symbolize mobile
users' walking paths. To turn this final version of the map into a positioning model,
Ekahau Manager requires explicit calibration according to the training phase of the
fingerprinting technique (sample points are recorded at many RPs in the walking
paths). The floor map used by the Ekahau Manager can be seen as an implicit
location model when calibrated as a positioning model. The map does not show
hierarchical or containment relationships between objects in a building, but is used
to create a coordinate system of each floor area.
The Ekahau Manager can also perform various analyses of the WLAN signals it
receives and process them to provide instant live tracking of a connected device. The
EPE, being the centerpiece of the EkahauTracking System, is responsible for keeping
track of all the devices and updating their position based on the information it
continuously receives from them. The EPE is a 2.5 dimensional positioning
solution. It cannot give a complete 3D coordinate of the estimated position.
What it can compute is mainly the 2D coordinates (x, y) and the floor the device
is on. The EAS is a set of helpful tools, examples, and easy programming interface
for third-party applications to quickly use EPE location information. Based on all
the aforementioned system components, the Ekahau tracking process operates
as follows:
* Firstly, a model of the desired space is created using Ekahau Manager.
Then, areas/rooms are scanned and Radio Frequency (RF) parameter measure-
ments obtained at different RPs using Ekahau Client (power loss, multipath