## 5 Solution of the Design and Testing
### Positioning and Construction
MED represents the intensity level of the gain value for receiving a packet message. In the chip design of this apparatus, there are 47 levels, each commencing with a 2 dB interval. According to the IEEE 802.15.4 standards, the assessment of a received signal strength across various channels is termed energy detection (ED). Its purpose lies in the computation of the channel selection at the network layer. The ED duration spans the transmission time of eight symbols, and a minimum ED value of 0 indicates that the received power is less than 10 dB, surpassing the sensing range of the receiving end. The ED value within the range of received signal strength must be no less than 40 dB. (4). Establish a Positioning Model  
Analysis of the Model  
After utilizing the 120\({}^{\circ}\) segmentation approach, given the limitation of not being able to densely position reference points outdoors, and considering that outdoor positioning typically falls within the line of sight, this study advocates for the application to be structured with utmost cost efficiency (i.e., deploying the fewest readers at the lower reference point) to achieve an optimal positioning accuracy. The 90\({}^{\circ}\) layout method was refined, giving rise to the inaugural 120\({}^{\circ}\) reference point layout method. The configuration of the wireless signal interference area generated using this method is elucidated in Figure 48.  
It is evident that the radii of circles A and B extend to 100 m each, resulting in each side of the equilateral triangle formed by r1, r2, and r3 precisely matching the radii of A and B. Consequently, the intersection arc between the two circles spans 120\({}^{\circ}\), forming a 120\({}^{\circ}\) layout, as depicted in Figure 49.  
Figure 48: The 120\({}^{\circ}\) segmentation method. The positioning reference coordinates engendered through this layout methodology are succinctly compiled following empirical measurements, as delineated in Table 10.  
(H) in Table 11 designates that it surpasses the presumed dB value of 172, signifying that the signal's potency received at the positional juncture is elevated, warranting its designation as a criterion for proximity to the reference point. Consider p2 in Table 7 as an example. If, in the process of assessing the signal's dB value, no reference point registers a value exceeding 172, the one closest to 172 will serve as the determinant for establishing the receiving range, thereby identifying the reference point closest to it. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Ref.** & \multicolumn{2}{c}{**Reference Point A**} & \multicolumn{2}{c}{**Reference Point B**} & \multicolumn{2}{c}{**Reference Point C**} & \multicolumn{2}{c}{**Reference Point D**} \\ \cline{2-10} / & & & & & & & & & \\ \cline{2-10}
**Take** & **RSSI** & **LQI** & **RSSI** & **LQI** & **RSI** & **LQI** & **RSSI** & **LQI** \\ \hline \(p1\) & 174(H) & 85 & 162 & - & - & - & - & - \\ \(p2\) & 165 & 30 & - & - & - & - & 171 & 60 \\ \(p3\) & 172(H) & 40 & 163 & 30 & - & - & 165 & 42 \\ \(p4\) & 168 & 42 &
\begin{tabular}{c} 172 \\ (H) \\ \end{tabular} & 55 & - & - & - & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Actual measurements of RSSIs and LQIs corresponding to different reference points. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**Ref. ** & \multicolumn{2}{c}{**Ref. Point A**} & \multicolumn{2}{c}{**Ref. Point B**} & \multicolumn{2}{c}{**Ref. Point C**} & \multicolumn{2}{c}{**Ref. Point D**} & \multicolumn{2}{c}{**Ref.