## 3 Materials and Methods
### Radio Access Network (RAN)  
Radio access network (RAN) is the implementation of both legacy and new radio technologies. New features such as multiple input, multiple output (MIMO), beamforming, and new dedicated radio bands (1-24 GHz) are available. These features enhance the radio performance of 5G. Due to its higher operating frequencies, 5G tends to be vulnerable to its environment. This issue is significant in warehouses or manufacturing sites, which tend to have higher penetration losses. To test the feasibility of a project, it is essential to study radio coverage analysis. The set of bands available for 5G new radio (NR) has been defined in the technical specification 3 GPP TS 38.101-1 Release 15 [26]. According to this technical specification, there are three major frequency bands: low (700 MHz), high (3.1-4.9 GHz), and very high (26 GHz). The use of each specific band depends on the geographical area. Table 2 represents Taiwan's current 5G frequency bands for individuals and private users. Frequency bands under 2.7 GHz have lower performance due to a higher concentration of cellular networks (3G and 4G) across the ultra-high-frequency band (UHF). In contrast, the C-band frequency range (3.4-3.6 GHz) is highly available. During the early phase of the 5G deployment in Taiwan, the central band provided at that time was N1. Nowadays, N78 is the most popular frequency band. N1 is the second most adopted frequency band in Taiwan. Currently, the leading mobile network operators (MNOs) in Taiwan offer five frequency bands, as shown in Table 3. The current bands offered cover low- to high-frequency bands. MNOs provide wireless network coverage maps to evaluate the service availability in a given location. However, this can differ from the network experience of each user. OpenSignal, a private analytics company, collects network parameters such as signal strength, available networks, or data speed of each application user. Thus, users can visualize the radio coverage map in their current location [27]. Radio coverage simulators are needed to predict the coverage of a custom wireless network. In the case of custom wireless networks, equipment parameters such as transmitting power or radiation patterns affect the result of the coverage. In this regard, VE2 DBE is \begin{table}
\begin{tabular}{c c c} \hline \hline
**Data Generation** & **Data Transmission** & **Analysis Methods** \\ \hline List of radio parameters & Data encryption & Round-trip time (RTT) \\ Building CAD file & TCP & Throughput \\ Data generation (\(\cdot\)CSV) & Wireshark & Packet analyzer \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The portions in the practice of the 5G digital twin. \begin{table}
\begin{tabular}{c c} \hline \hline
**Band** & \(f\) **(MHz)** \\ \hline N1 & 2100 \\ N3 & 1800 \\ N28 & 700 \\ N41 & 2500 \\ N78 & 3500 \\ N79 1 & 4700 \\ \hline \hline \end{tabular} 1  
\end{table} 
Table 2: Commercially Available 5G Frequency Bands in Taiwan. a free online radio simulator, merging the antenna parameters with location data from geographic databases such as OpenStreetMap, Bing Road, Bing Satellite, USGS Topo, USGS Sat, Open TopoMap, and OSM gray. The coverage file is a geo-referenced map of the antenna coverage in a selected area. This file contains multiple images, such as a radio coverage map (.PNG), terrain relief map (JPG), land cover map (.PNG), and population density map (.PNG). VE2 DBE can be used for radio coverage simulation in large-scale areas [28]. Physical obstacles and reflective materials affect the coverage of custom wireless networks notorious in environments such as warehouses or manufacturing scenarios. In these environments, accurate radio coverage requires both antenna parameters and obstacles' material parameters. In this regard, advanced electromagnetic simulators such as Altair Feko (winProp) enable radio network planning for small and large-scale areas [29]. Small-scale areas include buildings, warehouses, or manufacturing sites. Large-scale areas include urban and rural environments.