Information Technology Reference
In-Depth Information
Figure 2: Actual RF signal coverage.
Regardless of the distance estimation approach used, most of the existing
indoor and outdoor positioning systems need a number of reference nodes
whose position is known to accomplish the positioning estimation task.
2
Position detection techniques
The three main techniques for automatic detection of the position are
triangulation , scene analysis and proximity . Positioning systems can use
them separately or in combination. In this section we will describe the basic
concepts of each method and some existing deployment. Positioning systems
cited in this section will be described in more detail in the next section.
2.1 Triangulation
The triangulation method uses the geometric properties of triangles to
calculate the position of an object. It is divided into two subcategories:
lateration and angulation . The first one uses distances measurements and the
second uses angles measurements.
2.1.1 Lateration
The lateration technique calculates the position of an object by measuring
the distance between the object and reference points. In a 2D space it is
necessary to measure the distance between the object and three non-collinear
points. In a 3D space it is necessary to measure the distance between the
object and four non-coplanar points. The domain knowledge can reduce
the number of required measurements. For example, the Active Bat position-
ing system [4] measures the distance between mobile tags ( Bats ) within
 
 
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