## 4 Millimeter-Wave Channel Measurement at 39 GHz  
The channel measurements in NLOS environments were conducted in the urban microcellular environments of Qingdao, China, as shown in Figure 2.  
An omnidirectional antenna was used at the transmitter (Tx), with an operating frequency of 26.5-40 GHz. Moreover, the receiver (Rx) adopted a horn antenna (as shown in Figure 3) and its operating frequency was also 26.3-40 GHz. The MIMO channel measurement system is shown in Figure 4. The relevant measurement parameters are shown in Table 1.  
Figure 1: Sampling of scattered rays.  
Figure 2: The channel measurements in the NLOS scenario.  
The specific measurement process is shown in Figure 5. During measurement, Tx was fixed, and its coordinates were (2.9, 54.7, 9). A total of 10 points were selected for Rx, which was moved in increments of five meters along the gray line, namely, y = 62.9, z = 1.5, x = (10, 15, 20, 25, 30, 35, 40, 45, 50, and 55). Moreover, Rx was moved in the horizontal and vertical directions using a rotary table at each receiving point. In Figure 5, the 3D label indicates experimental data where the azimuth and elevation angles were measured, and the 2D label indicates experimental data where only the elevation angle was 0\({}^{\circ}\) and azimuth angles were measured at 5\({}^{\circ}\) intervals. The solid red lines represent the \(x\)-axis (along the direction of the building length) and the \(y\)-axis (along the direction of the building width),  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Physical Parameters** & **Value** \\ \hline Frequency (GHz) & 39 \\ Bandwidth (GHz) & 1 \\ Transmitting power (dBm) & 0 \\ The height of Rx/Tx antenna (m) & 1.5/9 \\ Transmitting antenna/gain (dBi) & Omnidirectional/6.19 \\ Receiving antenna/gain (dBi) & Horn/26.92 \\ The stepping of horn antenna & 5\({}^{\circ}\) \\ Polarization method of transmitting antenna & V \\ Polarization method of receiving antenna & V \\ \hline \hline \end{tabular}
\end{table}
Table 1: The measurement parameters in the urban microcellular environment.  
Figure 4: Real-time MIMO channel detection system.  
Figure 3: Antenna pattern of the E-plane and H-plane horn antennas and normalized antenna pattern at 39 GHz, where (**a**) is two-dimensional horn antenna pattern and (**b**) is three-dimensional horn antenna pattern.  
and the \(z\)-axis is measured along the direction of the building height. Moreover, the green lines represent the lawn. The power transmitted by the Tx is 0 dBm, the measurement bandwidth is 1 GHz, and both Tx and Rx are vertically polarized.  
The 3D measurements were performed for azimuth angles at \(5^{\circ}\) intervals and elevation angles at \(-10^{\circ}\), \(0^{\circ}\), \(10^{\circ}\), \(20^{\circ}\), and \(30^{\circ}\) at the receiving end when the receiving antenna was very close to the transmitting antenna. The farther the receiving antenna is from the transmitting antenna, the smaller the effect of the elevation angle on the path loss. Therefore, these data were collected for azimuth angles of every \(5^{\circ}\) and elevation angles of \(-10^{\circ}\), \(0^{\circ}\), and \(10^{\circ}\) at the Rx in NLOS environments. The complex relative permittivity of the wall is \(\varepsilon_{r}=3+0.005i\), which is taken from the reference literature.