# Study on the Deployment of Ultra-Wideband Positioning Base Stations in Pig Farms
## 4 Experimental Analyses
### Simulation and Analysis
Based on Figure 4 and statistical analysis, within the square area surrounded by the base stations, Schemes b to f exhibit a smaller HDOP value as the center point gets closer, while the VDOP and PDOP values increase. As for proximity to the base stations, the VDOP and PDOP values decrease while the VDOP values increase as the center point approaches. The scheme shows that when the distance between base stations is 150 cm, all three DOP values are smaller when closer to the center. Outside of this enclosed area, the DOP values increase. Figure 4: \(Cont.\)  
Figure 3: Coordinates of base stations when distance is different. Table 2 shows the following:  
As the side length of the base stations gets bigger and bigger, the HDOP value decreases gradually, and the VDOP and PDOP values increase gradually; for Scenario f, the maximum, minimum, and average values of HDOP are the smallest, and the maximum and average values of VDOP and PDOP are the largest, but the minimum values of VDOP and PDOP for the six scenarios are basically the same. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**DOP** & **Targets** & **a** & **b** & **c** & **d** & **e** & **f** \\ \hline \multirow{3}{*}{HDOP} & maximum & 1.65 & 1.51 & 1.49 & 1.48 & 1.47 & 1.47 \\  & minimum & 1.22 & 1.06 & 1.03 & 1.02 & 1.01 & 1.01 \\  & average & 1.44 & 1.29 & 1.26 & 1.25 & 1.24 & 1.24 \\  & maximum & 1.41 & 2.02 & 2.88 & 3.77 & 4.67 & 5.58 \\ \multirow{3}{*}{VDOP} & minimum & 0.86 & 0.97 & 0.99 & 0.99 & 1.00 & 1.00 \\  & average & 1.13 & 1.49 & 1.93 & 2.38 & 2.83 & 3.29 \\ \multirow{3}{*}{PDOP} & maximum & 2.17 & 2.41 & 3.13 & 3.96 & 4.82 & 5.71 \\  & minimum & 1.50 & 1.57 & 1.57 & 1.58 & 1.58 & 1.58 \\ \multirow{3}{*}{PDOP} & average & 1.84 & 1.99 & 2.35 & 2.77 & 3.20 & 3.64 \\ \hline \hline \end{tabular} Note: Scenarios a-f correspond, respectively, distance of base stations ranging from 150 cm to 900 cm.  
\end{table} 
Table 2: DOP values for simulation experiments with different base station spacing. Figure 4: Mesh and contour plot of HDOP, VDOP, and PDOP. Note: a-A\({}_{0}\), a-A\({}_{1}\), a-A\({}_{2}\), a-A\({}_{3}\) in Figure 3 is the base stations’ layout location. In this figure, the mesh plot of DOP, the X and Y coordinates are the location of the base stations; the Z coordinate is the value of DOP. The following summary can be obtained: when the base stations' height and layout shape are fixed, appropriate adjustment of the base station spacing can reduce the DOP value; the larger the range of the base stations, the HDOP maximum and minimum values will be smaller; the VDOP and PDOP minimum value does not change much; the base stations' spacing in 150 cm DOP value is relatively large; and the spacing in the range of 300 cm and above is better. Different shapes of the base station arrangements  
Comparison and analysis of the impact of different base station layouts on positioning accuracy are conducted under fixed base station spacing and height conditions. The base stations are arranged in four scenarios: an equilateral triangle with a side length of 600 cm (Scenario a), a square with a side length of 600 cm (Scenario b), a rectangle measuring 600 cm in length and 300 cm in width (Scenario c), and a rectangle measuring 300 cm in length and 600 cm in width (Scenario d). The layout and coordinates of the base stations are illustrated in Figure 5, A\({}_{0}\) to A\({}_{3}\) are the location coordinates of the base stations in the plan. From Figure 6 the HDOP values exhibit a decreasing trend towards the central point location within the enclosed area formed by the base stations, while they increase in proximity to the base stations. Similarly, both VDOP and PDOP values are observed to decrease near the base stations. Conversely, outside this enclosed area, DOP values demonstrate an increasing pattern with greater distances from the center. This can be obtained through Table 3:  
Scenario b, when the base stations are laid out as a square, the DOP value is the smallest.