# Investigations on Millimeter-Wave Indoor Channel Simulations for 5G Networks
## 3 Methodology and Simulation Setup  
This paper investigates the general indoor propagation channel characteristics at the mmWave. This includes the path loss exponent (PLE), Root-mean Square (RMS), delay spread (DS), and multipath temporal properties. The simulations were conducted in an indoor simulated environment; the environment was constructed using a ray-tracer software named Wireless InSite (WI), version 3.3.5, which has been validated over WLAN [29] and millimeter wave frequencies [20]. The software considers the effects of material electrical properties. It also allows the user to configure waveform, antenna types, and the properties of the transmitter and receivers. Simulations consider line-of-sight (LOS) and non-LOS (NLOS) scenarios. Four millimeter-wave frequencies were adopted, 28 GHz, 39 GHz, 60 GHz, and 73 GHz; their corresponding bandwidths are 0.8 GHz [22] and 2 GHz [30,31]. Figure 1 shows the simulated environment of the Chesham building at the University of Bradford. The access points (APs) transmit power to over 1450-1591 receiver points (RPs) (the number of RPs depends on AP coverage), and both APs and RPs are mounted on 1 m. The study considers three antenna pattern configurations, using directional antennae at both ends of the communications links to find the directional properties of the channel. It also considers the channel's omnidirectional properties by using an omnidirectional antenna and, finally, the directional antenna used at the transmitters and omnidirectional antenna used at the receivers. The WI permits the user to adjust a wide range of parameters, including antenna type, transmitted power, operating frequency, signal bandwidth, electrical constitutive parameters, number of reflections, transmissions, and diffractions, propagation model, ray-tracing method, sum complex electric fields, the number of propagation paths, etc. Table 1 summarizes the WI settings used in the simulations. Table 2 provides building material properties' values as a function of the operating frequencies, including conductivity (\(\sigma\)) and relative permittivity (\(\epsilon\)r); these values are based on the ITU recommendations [32]. Due to losses at high frequencies (path loss (PL) tends to increase by a factor of 20 \(log(f)\) dB, where f is the operating frequency), higher antenna gain is used at higher frequencies. More specifications on the antenna used are available in [33]. Figure 1: The simulated environment for the 3 rd floor in the Chesham building, University of Bradford. \begin{table}
\begin{tabular}{c c} \hline \hline
**Property** & **Setting** \\ \hline \multirow{3}{*}{Transmitter antenna} & Horn antenna: WR-15 (26.5–40 GHz) \\  & WR-15 (50–70 GHz) \\  & Omnidirectional \\ \hline \multirow{3}{*}{Receiver antenna} & Horn antenna: WR-15 (26.5–40 GHz) \\  & WR-15 (50–70 GHz) \\  & Omnidirectional \\ \hline \multirow{3}{*}{Transmitted power} & 23 dBm \\ \cline{2-3}  & 15 dB (WR-15 26.5–40 GHz) \\ \cline{2-3}  & 24 dB (WR-15 50–70 GHz) \\ \hline \multirow{3}{*}{Sum complex electric fields} & None \\ \cline{2-3}  & Number of reflections & 6 \\ \cline{2-3}  & Number of transmissions & 4 \\ \cline{2-3}  & Number of diffractions & 3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Wireless InSite settings. The WI uses the shoot and bouncing rays (SBR) as a ray-tracing method; it also uses the method of images to correct the SBR paths, which reduces the error in calculating received power. The Saleh Valenzuela model is widely used to describe the propagation channel environment at UWB frequencies; the model describes multipath behavior in indoor environments, suggesting that rays come in clusters. For indoor environments, if the time difference between two adjacent rays is more than 6 ns, the rays are said to come from 2 different clusters [34]. The raw information is taken from WI; the data are then analyzed using Matlab(R2023a) codes to estimate channel parameters.