## 5 Results and Validations  
The ABER performance of the proposed RIS-assisted mmWave massive MIMO system is examined under 3 GPP TR 38.901 V16.1.0 5G channel models using MATLAB R2023a. The channel matrices are generated for the desired number of realizations using the SimRIS channel simulator. The simulation setup is presented in Table 4.  
Figure 3 shows the ABER performance of 1 \(\times\) 4 M-MIMO for the InH--indoor office environment at 28 GHz for varying \(N\) values. To attain the desired ABER, \(N=64\), \(N=256\), and \(N=1024\) systems demand an SNR of \(\sim\)78 dB, \(\sim\)74 dB, and \(\sim\)71 dB, respectively. It is noted that SNR gain increases with increases in \(N\). For example, the \(N=1024\) system has a \(\sim\)7 dB SNR gain compared to the \(N=64\) system. Figure 4 depicts the ABER performance of 1 \(\times\) 4 M-MIMO for an InH--indoor office environment at 73 GHz for varying \(N\) values. To attain the desired ABER, the \(N=64\), \(N=256\), and \(N=1024\) systems demand an SNR of \(\sim\)88 dB, \(\sim\)84 dB, and \(\sim\)78 dB, respectively. When the number of reflecting items is 1024, there is an SNR gain of \(\sim\)10 dB over the \(N=64\) system and a \(\sim\)4 dB SNR gain over the \(N=256\) system. SNR gain increases with \(N\). In general, as frequency increases, so does path loss. By comparing Figures 3 and 4, we notice that the \(N=1024\) system requires an SNR of \(\sim\)71 dB for a frequency of 28 GHz, whereas the SNR required for 73 GHz is \(\sim\)78 dB, resulting in an additional \(\sim\)7 dB SNR to accomplish the same performance. Figure 5 shows the ABER performance of the \(N=256\) RIS-M-MIMO for an InH--indoor office environment at 28 GHz by varying the number of transmitting antennas, such as 4, 16, 64. To attain the desired ABER, \(N_{T}=4\), \(N_{T}=16\), and \(N_{T}=64\) systems demand an SNR of \(\sim\)73 dB, \(\sim\)67 dB, and \(\sim\)63 dB, respectively. SNR gains rise together with an increase in the transmitter antenna count. The \(N_{T}=64\) system has an SNR gain of \(\sim\)10 dB over the \(N_{T}=4\) system. Figure 6 depicts the same settings as Figure 5, except the carrier frequency, which is set to 73 GHz. \(N_{T}=4\), \(N_{T}=16\), and \(N_{T}=64\) systems demand an SNR of \(\sim\)84 dB, \(\sim\)77 dB, and \(\sim\)68 dB, respectively, to attain the desired ABER. SNR gains \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Values** \\ \hline Carrier frequencies (GHz) & 28 and 73 \\ MIMO configurations & \(1\times 4\), \(1\times 16\), \(1\times 64\) \\ Size of RIS array & 64, 256, 1024 \\ Number of channel realizations & \(10^{5}\) \\ Modulation & BPSK \\ Target ABER & \(10^{-4}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Simulation Setup. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Parameters** & **NLoS** & **LoS** \\ \hline \(n\) & 3.19 & 1.98 \\ \(\sigma\) (dB) & 8.29 & 3.1 \\ \(z\) & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Path loss attributes for UMi [25; 61]. Moving from 28 GHz to 73 GHz allows for larger bandwidth allocation to users, resulting in higher achievable data rates. Generally, interfering sources do not affect higher mmWave frequencies, resulting in lower interference and greater security. Additionally, smaller component sizes enable more extensive antenna arrays to be utilized. Figures 3-6  
Figure 5: ABER performance of \(N\)=256 RIS-M-MIMO for InH—indoor office environment at 28 GHz and varying \(N_{T}\) values. Figure 6: ABER performance of \(N\)=256 RIS-M-MIMO for InH—indoor office environment at 73 GHz and varying \(N_{T}\) values. show that moving from 28 GHz to 73 GHz increases the error rate for an indoor environment. However, the error rate performance can be improved by increasing \(N_{\rm T}\) and \(N\). Increasing \(N_{\rm T}\) at the access point (AP) is not always feasible for indoor environments. As a lightweight architecture, RIS with several components can be easily mounted in indoor settings to overcome the impact of propagation losses.