## 6 Simulation Results  
Table 1 presents the simulation parameters of the proposed LoRa system. A wireless channel model is provided by [47]. The received signal power of the receiver accessing the transmitter is provided as  
\[P_{rec}=P_{trans}-10a\log_{10}d+b+10c\log_{10}f_{c}+\lambda \tag{17}\]  
where \(P_{trans}\) and \(f_{c}\) are the transmit power and center frequency, respectively. The parameters of \(a,b\), and \(c\) are presented in Table 1. \(d\) is the distance between the node and data center and \(\lambda\) is a shadowing component that is modeled by a random variable of the log-normal distribution. In the simulation, we assume that the CRC detection error by CRC does not occur. This simulation assumes a noise figure in the RF front end is 0 dB. The typical value of the noise figure is around 6 to 8 dB [48]. As the noise figure becomes larger, the coverage, which is the maximal distance between the sensor and the data center for the availability of data gathering, becomes smaller. The evaluation of the impact of the noise figure on coverage reduction will be looked at in future work. Figure 6 illustrates the probability density function of the noise and CCI in each estimation scheme. Table 2 presents the estimation results for the average power and COR in each estimation scheme. In this evaluation, the interference-to-noise power ratio (INR) is 18.5 dB and the packet error rate is 0.044. In this figure, \"All packet use\", \"Only CRC OK\", and \"Ideal\" are the estimation schemes that adopt all the received packets, packets with CRC OK, and all the packets not including any bit errors. \begin{table}
\begin{tabular}{l l} \hline \hline Center frequency \(f_{c}\) & 923 MHz \\ \hline Spreading factor, \(N_{SF}\) & 7 \\ \hline LoRa bandwidth & 250 kHz \\ \hline SC Bandwidth & 200 kHz \\ \hline LoRa and SC transmission power \(P_{trans}\) & 13 dBm \\ \hline Number of packets for estimation & 1000 \\ \hline Number of symbols per packet, \(N_{pkt}\) & 200 \\ \hline COR of SC & 0.7 \\ \hline Distance between data centers and sensor in LoRa & 500 m \\ \hline Distance between data centers of LoRa and SC transmitter & 500 m to 900 m \\ \hline Propagation coefficient of the distance loss, \(a\)[47] & 4 \\ \hline Propagation offset, \(b\)[47] & 9.5 \\ \hline Propagation coefficient of the frequency loss, \(c\)[47] & 4.5 \\ \hline Transmitted antenna gain & 0 dBi \\ \hline Received antenna gain & 16 dBi \\ \hline Shadowing deviation [47] & 3.48 dB \\ \hline Shadowing coefficient & 0 \\ \hline Noise power-spectrum density & \(-174\) dBm/Hz \\ \hline Amplification rate of the low-noise amplifier & 60 dB \\ \hline Noise figure & 0 dB \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of the estimated power and COR in each estimation scheme. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Estimating Terms** & **Ideal** & **Proposed** & **All Packets Use** & **Only CRC OK** \\ \hline Noise + CCI power & \(-101\) dBm & \(-100\) dBm & \(-100\) dBm & \(-103\) dBm \\ Noise & \(-120\) dBm & \(-120\) dBm & \(-117\) dBm & \(-120\) dBm \\ COR & 0.70 & 0.70 & 0.96 & 0.22 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of the estimated power and COR in each estimation scheme. Figure 6: Example of estimating noise and CCI plus the noise power distribution in each estimation scheme and ideal. In this figure, the probability density function estimated by the proposed scheme is closest to that of \"Ideal\". The reason for the degradation of \"All packet use\" is the received packets, including the error bits causing missed detections of POD and PUD. In the \"Only CRC OK,\" the interference is negligible in that the packet error does not occur; thus, the estimated power of the CCI is lesser than the practical one. In the proposed estimation, although packet error occurs, the estimated power of the CCI over a certain threshold is considered to be a highly accurate estimation; thus, the accuracy of the estimation is improved.