## 4 Simulation Results
### Simulation Parameters  
To establish communications between the SM and DC, the authors opt to use the Wi-SUN standard for RF-based communications and the IEEE 1901.2 standard for NB-PLC communications. These standards provide the necessary specifications and guidelines for implementing the communication protocols in AMI systems, ensuring compatibility and reliable data exchange. For NB-PLC, according to the IEEE 1901.2 standard, the OFDM symbol contains a 256-point IFFT adjoined by a cyclic prefix (CP) corresponding to 30 samples. These samples are used to remove the inter-symbol interference (ISI) which is created by the channel effect. For RF, parameters are selected by the authors according to the IEEE 802.15.4g MR-OFDM standard under option 2. They assume that 1 OFDM symbol is the size of 64 subchannels and a CP comprising 16 symbols. Figure 8: Proposed methodology adopted to study the environmental impact of RF and PLC for AMI. As the OFDM signal is transmitted through the RF or NB-PLC channel, it encounters reflections, delays, and attenuation due to the varying characteristics of the communication environment. To mitigate the effects of multipath fading, channel distortion, and ISI, a zero forcing (ZF) equalizer is implemented in the OFDM system. As far as the noise is concerned, AWGN, cyclostationary impulsive noise, and Gaussian mixture impulsive noise (GMM) are modelized for wired and wireless communication channels. The specific selection of the noise model for each channel and each area is outlined in Table 3.  
The environment design in this paper characterizes RF and NB-PLC channels in distinct geographical areas: rural, urban, and industrial. These characteristics are mandatory to correctly design the AMI system. Therefore, the authors define the key parameters specific to each environment, including (1) the number of paths for wireless links, (2) the length of the wired link, and (3) the noise model associated with each link. Regarding NB-PLC, the authors choose to implement three branches between the SM and DC. First, in rural environments, the smart metering system is typically designed to cover larger areas and longer distances between devices. This requires the use of higher-power communication technologies, such as NB-PLC or RF, to ensure reliable communication over longer distances. In this paper, the authors use 1 km as a distance between the SM and DC. For the RF communication system, the distance also varies depending on various factors, such as the presence of physical obstacles. This variation is modeled by the RF path number. Therefore, the authors choose the electrical line length that is greater than 200 m and the path number that is equal to 5 with AWGN. Second, in urban environments, the AMI system is typically designed to handle a larger number of connected devices compared to rural environments. This system is designed to operate over short distances and with higher-power communication technologies, NB-PLC or RF, due to the higher density of \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Area** & **SM-DC Distance** & **RF Path Number** & **RF Noise Model** & **NB-PLC Line Length** & **NB-PLC Noise Model** \\ \hline Rural & 1 km & 5 & AWGN & \textgreater{}200 m & AWGN \\ \hline Urban & 80 m-200 m & 10–20 & AWGN/GMM & 20–50 m & Cyclostationary Impulsive Noise \\ \hline Industrial & 50 m & 40–50 & GMM & \textless{}15 m & Cyclostationary Impulsive Noise \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters of characteristics. Figure 9: Block diagram of the OFDM system. devices and potential for interferences. In this paper, the authors use 200 m as the distance between the SM and DC. For NB-PLC, and the authors choose the electrical line length between 30 and 50 m with cyclostationary impulsive noise. For RF, the path number is between 10 and 20 with GMM noise and/or AWGN. Third, in industrial environments, the AMI system is typically designed to also handle a large number of devices in complex and noisy environments.