Download A Hardware Platform for Communication and Localization

Location Area
R3
R2
R1
R1
R2
R3
Base Station
Figure 36 Maximum likelihood ranging area division. The orange dot stands for Base Station; Red and blue ring intersecting with each other are the possible ranging area of two base stations respectively. The maximum distance Dmax and minimum distance Dmin are derived from the path loss model and RSSI value. If we have these two base stations merely, then the location of transmitter is predicted to be in the insect part of R2. Figure 37 give a quick glance of the predicted location. White meshes in this figure indicate the intersection of two rings. If we add another sensor as base station, very likely the third ring will only intersect with one of the white mesh. By averaging the possible location coordinates as predicted location, an extra base staion could increase the localization accuracy in a great deal. In this thesis we will use up to eight base stations for simulation to pursue a better result. Then the centroid result, i.e., the average of all intersected coordinates are predicted as the transmit source. 61