# Wideband Channel Characterization for 6G Networks in Industrial Environments
## 4 Measurement Campaigns  
The measurements were conducted using a commercial VNA, R&S ZVA 67 [53], and up-converters, R&S ZVA-Z110 [54]. The up-converters not only convert the signal from 18 GHz to 108 GHz, but also amplify the signal so that no additional amplifiers are required. The setup was calibrated using through-offset-short-match (TOSM) to remove the effects from the connectors, cables, and equipment. The setup resulted in a noise floor of \(-100\) dBm with an intermediate frequency (IF) of 10 MHz. Horn antennas were connected to the up- and down-converters with one acting as a transmitter (Tx) and the other as a receiver (Rx). A photo of the measurement equipment and the connections is shown in Figure 1. Both antennas were set at a height of 1.6 m from the floor, with a gain of 21.14 dBi and an azimuth half power beam-width (HPBW) of 15.7\({}^{\circ}\) at the measurement frequency of 108 GHz [55]. To cover a wider angle, the measurements were repeated with antennas set at azimuth angles of 0\({}^{\circ}\), \(\pm 15^{\circ}\), \(\pm 30^{\circ}\), \(\pm 45^{\circ}\), and \(\pm 60^{\circ}\). This procedure expanded the beam-width of the antennas to 137.5\({}^{\circ}\) (120\({}^{\circ}\) + 15.7\({}^{\circ}\)), enabling the capturing of more environmental effects of the channel. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Frequency (GHz)** & **Scenario** & **Link Length (m)** & **Channel Characteristics** \\ \hline
[46] & 28 & Factory LoS and NLoS & 100 & Path loss \\
[47] & 28 & Engineering workshop & - & Reflection \\  & & Circle-shaped machine hall & 11.5–42 & Path loss and RMSDS \\
[49] & 28 & LoS and NLoS & 11.5–42 & Path loss and RMSDS \\
[50] & 28 & Circle-shaped machine hall & 4–26 & Path loss and RMSDS \\
[51] & 57–62 & Metal cabinet & 0.25–2.5 & Path loss and RMSDS \\
[44] & 28 and 60 & Factory LoS and NLoS & 35 & Path loss and RMSDS \\
[52] & 60 & LoS and NLoS in & 10–100 & Throughput \\  & & different industrial settings & 10–100 & Throughput \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Channel characterization studies in indoor industrial environments in the mmWave band. The VNA was configured to measure the channel transfer function \(S_{21}\) in the frequency domain from 107 to 109 GHz, i.e., central frequency of 108 GHz and span of 2 GHz with 2001 frequency points (a step size of 1 MHz). LoS measurements for distance values ranging from 0.5 to 5 m with an increment of 0.5 m were conducted. The measurement setup parameters are listed in Table 3. The measurements were repeated in three different locations, namely:  
* Manufacturing hall at Dokka Fasteners AS. This is a big hall that contains many pieces of heavy duty equipment. The measurements were carried out in a particular place inside the hall between two closed sides as shown in Figure 2. One side was enclosed in metallic shelves containing many pieces of heavy-duty equipment inside the wooden boxes. The other side contained many robotic types of machinery surrounded by a metal fence with an alarm metallic box and a grille door that was closed during the measurements, as shown in Figure 2.
* Test room at Dokka Fasteners AS, which contains a few pieces of heavy duty equipment, as shown in Figure 3. The room contained two big metallic machines on the right side. On the left side, there were metallic shelves containing many pieces of heavy-duty equipment inside the wooden boxes and two metallic machines, as shown in Figure 3.
* Manufacturing laboratory (MANULAB) at the Norwegian University of Science and Technology (NTNU). It contains many pieces of medium size equipment, as shown in Figure 4.  
Figure 1: Measurement equipment setup photo to show the cable connection to the VNA and the frequency converters. Figure 3: Measurement setup in the Test room at Dokka Fasteners AS. Two big metallic machines are located on the right side. Metallic shelves with may pieces of heavy-duty equipment inside the wooden boxes and two metallic machines on the left side.