# Comparative Study of Indoor Propagation Model Below and Above 6 GHz for 5G Wireless Networks
## 5 Experimental Setup  
The wideband measurements were conducted using channel sounder equipment as shown in Figure 1. The arbitrary waveform generator (AWG) M8190 (Keysight Technologies, Santa Rosa, CA, USA) was used to generate wideband differential baseband in-phase quadrature (IQ) at the transmitter; it could also output direct intermediate frequency (IF) signals with channel sounding. The baseband arbitrary waveform signal provided 1 ns multipath resolution from a pseudo random binary sequence (PRBS). At the receiver, 12-bit high-speed digitizer (bandwidth = 1 GHz) was used at the receiver for signal acquisition. Details of the measurement equipment can be found in [30]. The measurements were conducted at two different frequencies 3.5 GHz and 28 GHz, along a corridor on the 15 th floor of the Menara Tun Razak Building on the Universiti Teknologi Malaysia Kuala Lumpur campus. For LOS scenario, the Tx azimuth (Az) /elevation (El) angles are \(0^{\circ}/0^{\circ}\) and the Rx azimuth (Az)/elevation (El) angles are \(0^{\circ}/0^{\circ}\). For NLOS scenario, to cover the edge-wall diffraction, the Tx azimuth (Az)/elevation (El) angles are \(45^{\circ}/0^{\circ}\) and the Rx azimuth (Az) elevation (El) angles are \(0^{\circ}/0^{\circ}\).  
The measurements have been conducted in the corridor with a size of 2.4 m \(\times\) 20 m, and the ceiling height is 2.8 m. It has plywood doors, and the walls are constructed of gypsum board and glass. The floor is covered with glazed ceramic tiles, and the corridor ceiling is made of fiberglass materials. A pictorial view of the measurement set up and environment is shown in Figure 2.  
To collect all multipath components (MPCs) above the threshold (20 dB below the strongest MPC) [41] from all objects in the corridor, the horn antennas with high gains and wide beamwidths were used in this scenario. Wideband horn antenna (2-24.5 GHz, AINFO Inc., Irvine, CA, USA) was used for Tx and Rx at 3.5 GHz band. The antenna gain is 9 dB and the half power beamwidth (HPBW) values are 58.97\({}^{\circ}\) and 61.42\({}^{\circ}\) for elevation plane (E-plane) and azimuth plane (H-plane), respectively. At 28 GHz band, a wideband horn antenna (10-40 GHz, ETS-Lindgren Inc., Cedar Park, TX, USA) was used with gain of 11.6 dB and the HPBW values are 44.8\({}^{\circ}\) and 37.6\({}^{\circ}\) for E-plane and H-plane, respectively for Tx and Rx. At Rx side, a wideband low noise amplifier (LNA, 18-40 GHz, ETS-Lindgren Inc., Cedar Park, TX, USA) was used with gain of 40.3 dB. The wider beamwidth horn antennas have been used that can collect received signal from all objects (i.e., walls, doors and windowsfor azimuth plane and celling and floor for elevation plane), instead of using narrow beamwidth horn antennas with HPBW below 10\({}^{\mathrm{o}}\) and different azimuth and elevation angles.  
The measurement parameters set up are listed in Table 1. Two scenarios of measurement were carried out along the corridor, LOS and NLOS as shown in Figure 3. For both scenarios, the transmitter (Tx) sets were fixed, whiles the receiver (Rx) sets were moved along the corridor and the received waveforms were recorded at each 1 m up to the maximum Tx-Rx separation distance, which was 20 m. For the NLOS scenario, the Rx antenna was blocked by the edge of the wall as shown in Figure 3. Here, in this scenario the diffraction phenomena due to the edge shadow has been investigated.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameter** & **Value** & **Value** \\ \hline Carrier Frequency (GHz) & 3.5 & 28 \\ Transmit Power & 0 dBm & 0 dBm \\ Polarization & Vertical & Vertical \\ Antenna Gain (dB) & 9 & 11.6 \\ Tx and Rx Antenna /HPBW (degree) & 58.97 & 44.8 \\ Tx /Rx Antenna Height (m) & 1.5/1.5 & 1.5/1.5 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Measurement Parameters.  
Figure 1: Measurement Equipment.  
Figure 2: Measurement Environment.