## 4 Simulation Results
### Urban Environment  
The authors simulate the performance of both links in an urban environment for two scenarios. In the first scenario, the RF path number is equal to 20 with AWGN, the NB-PLC line length is set to 20 m, and the noise is cyclostationary impulsive noise.  
On the one hand, Figure 12 illustrates that, for SNR values lower than 25 dB, the RF link outperforms the NB-PLC link. There is an approximate 7 dB gap observed for a BER of \(10^{-2}\). This indicates that despite the environmental density, the wireless link performs better than the wired link. Thus, the electrical network topologies within buildings significantly attenuate the signal transmitted between the SM and DC.  
On the other hand, for an SNR greater than 25 dB, the NB-PLC link outperforms that of the RF link, with an approximate 13 dB gap observed for a BER of \(10^{-3}\). These results demonstrate that despite the low level of noise, the BER of the wireless link does not decrease considerably.  
From [51], the authors select experimental sites in Korea according to the customer type, and measure signal and noise powers at different measurement points. Communication performances are observed and analyzed for practical AMI field environments.  
In fact, a series of experimental measurements were conducted in a commercial environment [51]. The results are presented in terms of PER, which is expressed as a function of the BER in Equation (9).  
\[\textit{PER}=\textbf{1}-(\textbf{1}-\textit{BER})^{\textit{packet}\_\textit{ length}} \tag{9}\]  
Figure 12: RF vs. NB-PLC performances in an urban environment: 1 st scenario for a dense urban environment and a measurement point (MP (X)).  
The authors selected a measurement point (MP) characterized by a distance of 75 m between the SM and DC, corresponding to a high-density urban environment in the case of this paper. At this MP, the PER is equal to 90% and the SNR is equal to 18 dB. By applying Equation (9), and with a packet_length = 100 bytes, the obtained BER is \(2.10^{-2}\), which corresponds to an SNR = 18 dB. Figure 12 presents this measurement point and confirms the simulation results obtained in this case.  
To investigate the impact of the path number for the RF channel and the line length for the PLC channel on the performance of the communication system, a second scenario is defined. It represents an urban area characterized by moderate congestion and noise. In this scenario, the authors decrease the path number parameter from 20 to 10 and increase the line length from 20 m to 50 m.  
Figure 13 shows that for SNR values less than 25 dB, the BER performances are similar for both channels. However, for SNR values greater than 25 dB, the PLC is more suitable. Thus, buildings in urban areas attenuate the RF signal, despite the complexity of the electrical network.  
Furthermore, the authors compute the NB-PLC data rate at a BER equal to \(10^{-4}\). According to Figure 13, it is equal to 195 kbps, which corresponds to the average data rate value, which is 200 kbps in the G3-PLC standard, depicted in Table 1.  
Compared to the rural area, it can be observed that an increase in the number of paths and the complexity of the network topology impact the transmission performance of the channels in urban areas.