## 5 Results and Validations
Figure 7 shows the ABER performance of a \(1\times 4\) M-MIMO for an outdoor UMi--street canyon environment at 28 GHz by varying the \(N\) values. To attain the desired ABER, the \(N=64\), \(N=256\), and \(N=1024\) systems demand an SNR of \(\sim\)83 dB, \(\sim\)75 dB, and \(\sim\)66 dB, respectively. It is observed that when \(N\) increases, the SNR gain does as well. For example, the \(N=1024\) system has an SNR gain of \(\sim\)17 dB compared to the \(N=64\) system. According to Figures 3 and 7, the SNR necessary for \(N=1024\) is \(\sim\)66 dB for the outdoor environment and \(\sim\)71 dB for the indoor environment. When it comes to indoor environments, spatial correlation has a substantial impact on ABER performance. Figure 8 depicts the ABER performance of the \(1\times 4\) M-MIMO for an outdoor UMi--street canyon environment at 73 GHz when \(N\) is varied. To attain the desired ABER, \(N=64\), the \(N=256\), and \(N=1024\) systems demand an SNR of \(\sim 88\) dB, \(\sim\)82 dB, and \(\sim\)72 dB, respectively. When the number of reflecting items is 1024, there is an SNR gain of \(\sim\)16 dB over the \(N=64\) system and a \(\sim\)6 dB SNR gain over the \(N=256\) system. For \(N=1024\), the SNR necessary to attain the desired ABER is \(\sim\)66 dB for a frequency of 28 GHz and \(\sim\)72 dB for a frequency of 73 GHz. The performance suffers as a result of increased frequency. We can deduce from Figures 4 and 8 that the ABER performance in an indoor environment is inferior to that in an outdoor environment. This is due to the influence of spatial correlation. Figures 7 and 8 show that the error rate increases when the operating frequency increases. However, to acquire the benefits of a higher frequency in the outdoor environment, we can provide the BS with a larger number of antennas and the passive RIS with a larger \(N\)  
Figure 7: ABER performance of RIS-1 \(\times\) 4 M-MIMO for the UMi—street canyon environment at 28 GHz and varying \(N\) values. The RIS with more reflecting elements can be easily mounted outdoors. More transmitting antennas and reflecting elements in higher operating frequencies can form narrower beams, offering stable and reliable communication. Figure 9 shows the ABER performance of \(N=256\)  RIS-M-MIMO for the UMi--street canyon outdoor environment at 28 GHz by varying the number of transmitting antennas, such as 4, 16, 64. To attain the desired ABER, the \(N_{T}=4\), \(N_{T}=16\), and \(N_{T}=64\) systems demand an SNR of \(\sim\)75 dB, \(\sim\)68 dB, and \(\sim\)65 dB, respectively. SNR gains increase with \(  
Figure 10 depicts the ABER comparison of continuous infinite resolution and discrete reflection phase RIS under InH- indoor office environment at 28 GHz. To attain the desired ABER, the continuous phase RIS, 1-bit discrete phase RIS, and 2-bit discrete phase RIS demand an SNR of \(\sim\)78 dB, \(\sim\)90 dB, and \(\sim\)84 dB, respectively. The 2-bit discrete phase RIS has an SNR gain of \(\sim\)6 dB over the 1-bit discrete phase RIS. The 1-bit discrete phase RIS maps the phase shifts to 2 discrete phase levels, and the effect of the residual phase in (11) will be significant. Therefore, \(\epsilon^{\prime}\) decreases. However, the 2-bit discrete phase RIS maps the phase shifts to 4 discrete phase levels, and the effect of the residual phase will be reduced; therefore, \(\epsilon^{\prime}\) increases. Doubling \(P\) improves the SNR gain by \(\sim\)6 dB. By increasing \(P\), the performance of the discrete phase RIS is approaching the ideal continuous phase RIS. A similar performance can also be observed in the outdoor environment, which is evident from Figure 11.  
The proposed system can be adapted for scenarios involving multiple users, as illustrated in Figures 1 and 2, it can be integrated with time division multiple access (TDMA). This setup divides the total time among the users (\(L\)). Each user receives a time slot of \(1/L\) duration, during which all elements of the RIS are dedicated to that specific UE.