## 5 Solution of the Design and Testing
### Positioning and Construction
At the transmitting end, \(\mathrm{P_{TX}}\) was employed, and at the receiving end, \(\mathrm{P_{RX}}\) was utilized. \(\mathrm{G_{TX}}\) represents the gain value of the transmitting end, and \(\mathrm{G_{RX}}\) is the gain value of the receiving end, as articulated in Equation (14). \[P_{RX}=P_{TX}\times G_{TX}\times G_{RX}\bigg{(}\frac{\lambda}{4\pi d}\bigg{)}^{2} \tag{14}\]  
where \(\lambda\) signifies the wavelength, and d denotes the distance in the signal energy distribution curve between the transmitting device and the receiving device. It is evident that the RSSI value of the tag is at a direct viewing distance, as portrayed in Figure 45. In considering a 90\({}^{\circ}\) segmentation as an instance, the energy distribution of the smart meter (SM) within the sensing range may yield distinct RSSI intensity-sensing indicators at varying distances. The RSSI intensity received by the ZigBee device reference node is observable. In response, the RSSI value within the range of 0 to 20 m exhibits relative elevation. The mean RSSI index remains above 172; however, the gradient of the entire curve is remarkably gentle, rendering almost imperceptible distinctions in terms of distance. As illustrated in Figure 46, within the interference region where the two circles intersect in either the 90\({}^{\circ}\) segmentation method or the 60\({}^{\circ}\) segmentation method, the intensity exhibits minimal variation. Consequently, the effective distance becomes challenging to ascertain. Hence, additional auxiliary methods should be introduced to discern the label's location. Figure 45: The relationship between the sensing of the devices using the 90\({}^{\circ}\) segmentation method. \begin{table}
\begin{tabular}{c c} \hline \hline
**Distances (m)** & **RSSI (dB)** \\ \hline
60 & 166.86 \\
70 & 167.16 \\
80 & 164.53 \\
90 & 161.57 \\
100 & 162.89 \\
110 & 161.75 \\
120 & 162.07 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: _Cont._An alternative means of gauging distance involves employing an additional metric to assess its potential impact on the precision of positioning determinations. This metric is denoted as the LQI [63; 64], primarily revealing the quantity of packets necessitating retransmission to reach the receiving terminus. The testing methodology entailed designating one of the two sensing nodes as a label and continually dispatching packets in a cyclic manner, while the counterpart device logged the LQI value. Throughout the testing procedure, the location from which the SM emitted the signal was adjusted and gauged from 0 to 45 m, reiterated over 20 cycles, and executed with three distinct tags. Based on the LQI measurement outcomes that the MDPA algorithm, the findings were consolidated thread transection results, as shown in Figure 47.  
While the quality of wireless packet transmission naturally diminishes with increasing distance, an examination of the aforementioned figure revealed distinct characteristics among three different tags. When observed directly and without impediments, both the LQI and RSSI exhibit descending traits. The LQI value, ranging between 0 and 255, serves as an indicator where the maximum value signifies an optimal state of link quality. However, in principle, the LQI lacks a deterministic dependence on distance. Par  
Figure 46: The relationship between the sensing of the devices using the 60\({}^{\circ}\) segmentation method. Figure 47: SM-ooo device received anchor point quality indicator LQI. may be widely separated, and despite the signal's feebleness, a high LQI value can still be attained under conditions of low background noise or if the modulation method itself boasts robust anti-noise capabilities. Typically, the LQI primarily finds application in network optimal cost routing and data diffraction return coordinators [59]. The numerical derivation in the LQI is computed based on the bit error rate, as demonstrated in Equation (15):  
\[RED=(47-\text{MED})\times 6 \tag{15}\]  
If (ED < 0), then ED = 0; if ED > 255, then ED = 255.